Remote Patient Monitoring in Chronic Heart Failure

Cardiology in Review Volume21,Number3,May/June2013 www.cardiologyinreview.com | 141

Review ARticle

Abstract: Heart failure (HF) poses a significant economic burden on our health-care resources with very high readmission rates. Remote monitor-ing has a substantial potential to improve the management and outcome of patients with HF. Readmission for decompensated HF is often preceded by a stage of subclinical hemodynamic decompensation, where therapeutic interventions would prevent subsequent clinical decompensation and hospi-talization. various methods of remote patient monitoring include structured telephone support, advanced telemonitoring technologies, remote monitor-ing of patients with implanted cardiac devices such as pacemakers and defi-brillators, and implantable hemodynamic monitors. current data examining the efficacy of remote monitoring technologies in improving outcomes have shown inconsistent results. various medicolegal and financial issues need to be addressed before widespread implementation of this exciting technology can take place.

Key Words: heart failure, structured telephone support, telemonitoring, implantable hemodynamic monitors

(Cardiology in Review 2013;21: 141150)

Telemedicine is a rapidly growing area where wireless technology is employed for remote follow-up of patients. telemonitoring is defined as the use of communications technologies to monitor and transmit physiologic data related to patient status. various physi-ologic parameters, such as heart rate, blood pressure, rhythm, blood sugar, and filling pressures, may be monitored with these technolo-gies. this may help to better manage chronic diseases like hyper-tension, diabetes, and congestive heart failure (cHF). Between July 2003 and December 2007, the veterans Health Administration introduced a national home telehealth program, care coordination/Home telehealth (ccHt) to coordinate the management of chronic conditions and to prevent unnecessary hospital admissions. ccHt, provided by more than 5000 trained staff, involves the systematic implementation of health informatics, home telehealth, and disease management technologies. Data obtained from more than 17,000 patients enrolled in ccHt shows a 25% reduction in number of bed-days of care, 19% reduction in hospital admissions, and a mean sat-isfaction score rating of 86%.1

Patients with cHF represent an enormous burden on health-care resources, primarily because of the number of recurrent hos-pitalizations. Despite recent advances in pharmacotherapy and

device therapy, the rehospitalization rate remains unacceptably high. Approximately 27% of Medicare beneficiaries with cHF are rehospitalized within 30 days of discharge from the hospital, the highest rehospitalization rate among all medical conditions neces-sitating hospitalization.2 in a recent study of 30,136 Medicare patients with cHF discharged home from the hospital,3 21.3% of patients were readmitted within 30 days. Patients who had higher early follow-up rates after discharge had a lower risk of 30-day readmission in this study.4 Acute decompensation of cHF remains a frequent cause of rehospitalization and death in these patients. Although our understanding of the pathophysiology of cHF has advanced substantially, our ability to predict which patients will be hospitalized for acute decompensation is limited. Patients require close monitoring for changes in symptoms, fluid status, medica-tion and dietary adherence, and early detection of arrhythmias. Given the large numbers of patients who require close monitor-ing and frequent contact with medical professionals, telemonitor-ing is potentially a more realistic option. timely recognition and early intervention could potentially prevent and reduce clinical decompensation, leading to fewer emergency department visits and hospital admissions. Patients with poorly controlled cHF who experience recurrent hospitalizations might potentially benefit from this technology. Another area where frequent monitoring of patients would be of significant benefit is arrhythmias, the most common one being atrial fibrillation. telecardiology is an entity that refers to the application of telemedicine technology in the field of cardiology, especially for the management of cHF, arrhythmias, and the follow-up of implanted devices.

STRUCTURED TELEPHONE SUPPORT AND TELEMONITORING

in patients who cannot frequently make it to a clinic, structured telephone support (StS) and telemonitoring can provide specialized care to patients. StS is a form of monitoring that involves contact between the patient and the cHF nurse or physician at regular intervals. the patients symptoms and weight can be followed-up and the care provider can ensure compliance with pharmacotherapy and lifestyle changes (Fig. 1). Major trials on remote monitoring and their results are summarized in table 1.521 in a cochrane review of 25 randomized controlled trials of StS or telemonitoring as compared with standard practice for patients with cHF, StS was evaluated in 16 trials (n = 5613), and telemonitoring in 11 trials (n = 2710).22 telemonitoring was associated with a significant reduction in all-cause mortality (relative risk [RR], 0.66; 95% confidence interval [ci], 0.540.81; P < 0.0001) and cHF-related hospitalizations (RR, 0.79; 95% ci, 0.670.94; P = 0.008). StS demonstrated a nonsignificant trend toward reduction in all-cause mortality (RR, 0.88; 95% ci, 0.761.01; P = 0.08) and significant reduction in cHF-related hospitalizations (RR, 0.77; 95% ci, 0.680.87; P < 0.0001). Both the interventions were associated with improved quality of life, reduced health-care costs, and better evidence-based prescribing. inconsistent data made it difficult to adequately assess the length of hospital stay in the meta-analysis. Since this meta-analysis was published, 2 large randomized trials were published that raised concerns regarding the efficacy of remote monitoring strategies.

copyright 2013 by lippincott williams & wilkinsiSSN: 1061-53772103-0141DOi: 10.1097/cRD.0b013e318276198b

cardiology in Review

21

3

2013 by lippincott williams & wilkins

1061-5377

10.1097/cRD.0b013e318276198b

2013From the *Department of Medicine, Division of cardiology, New York Medical col-

lege/westchester Medical center, valhalla, NY; Department of Medicine, North Shore long island Jewish Health System, Manhasset, NY; and Department of Medicine, Division of cardiology, Minneapolis Heart institute at Abbott North-western Hospital; and Hennepin county Medical center, Minneapolis, MN.

Disclosure: the authors have no funding, financial relationship, or conflict of interest to disclose.

correspondence: chandrasekar Palaniswamy, MD, New York Medical col-lege, Division of cardiology, Macy Rm. 138, valhalla 10595, NY. e-mail: [email protected].

RemotePatientMonitoringinChronicHeartFailureChandrasekar Palaniswamy, MD,* Aaron Mishkin, MD, Wilbert S. Aronow, MD,* Ankur Kalra, MD,

and William H. Frishman, MD*

cRD

200358

Palaniswamy et al

Remote Patient Monitoring in Chronic Heart Failure

2013May/June

Naresh

XXX

142 | www.cardiologyinreview.com 2013 Lippincott Williams & Wilkins

Palaniswamy et al Cardiology in Review Volume21,Number3,May/June2013

the telemonitoring to improve Heart Failure Outcomes (tele-HF) study was a multicenter, randomized study of 1653 patients who had recently been hospitalized for HF.20 Patients were randomized to undergo either telemonitoring (826 patients) or usual care (827 patients), with a primary end point of readmission or death within 180 days of enrollment. telemonitoring was accomplished by an interactive voice-response system that transmitted daily information about symptoms and weight to patients clinicians for review. there were no differences neither in terms of the primary end point (52.3% for telemonitoring vs 51.5% for usual care; P = 0.75) nor in terms of mortality (11.1% vs 11.4%; P = 0.88).20

the telemedical interventional Monitoring in Heart Failure (tiM-HF) study was a randomized controlled clinical intervention trial to determine the impact of telemedical monitoring on mortality in patients with ambulatory HF.21 A total of 710 stable, patients with ambulatory HF were randomly assigned to telemedical management (n = 354) or usual care (n = 356). Remote telemedical management used portable devices for electrocardiography, blood pressure, and body weight that transmitted encrypted data via cell phones to the telemedical centers. if any changes were noted by the telemedical staff in regard to these parameters, the patients general practitioner was informed. the patients primary physicians remained their care-givers throughout the study. the primary end point in the study was all-cause mortality, with the first secondary end point noted as com-posite of cardiovascular mortality or hospitalization caused by HF. Of the patients assigned to the telemedicine arm, 287 (81%) were at least 70% compliant with daily data transfers and no break for more than 30 days (except during hospitalizations). After a median follow-up of 26 months, telemedical management had no significant effect on HF hospitalization (hazard ratio [HR], 0.89; 95% ci, 0.671.19; P = 0.44) as compared with usual care. the results of the tele-HF and the tiM-HF trials underline the importance of a thorough, inde-pendent evaluation of these newer strategies before their widespread adoption in clinical practice.

the negative findings from these studies should not be taken as a complete denunciation of telemonitoring systems for cHF

management. they emphasize the importance of the circle of home management of heart failure.23 this consists of the following ele-ments: measurement of physiological information that would reliably predict decompensation, transmission of data, processing of data by qualified personnel, timely intervention by contacting the patient, reassessment, and follow-up to confirm improvement in clinical status (Fig. 2). An effective home monitoring strategy must contain all the aforementioned elements to be successful. there are many potential areas where this circle could become disconnected, leading to failure of this strategy. the physiologic parameters that are mea-sured (weight and symptoms) may not be sensitive enough to predict decompensation. As with any medical intervention, patient adher-ence must always be considered. in the tele-HF study, only 55% of the patients assigned to the telemonitoring group used the system at least 3 times weekly by the end of the study, and 14% of the patients never used it at all. How the information obtained was processed and acted upon would also have a significant bearing on the end points. the team member receiving the data should be empowered to contact the patient directly with a treatment plan. the strategy of discussion with a physician before recommending a plan to the patient, as done in tele-HF study, might result in delays and failure of this strategy. Data received may not be triaged appropriately as health-care pro-fessionals may be overwhelmed by the magnitude of information received. this, along with heterogeneity of outcome measures that were studied, would explain inconsistent results obtained on the effi-cacy of remote monitoring strategies in various studies.

DEvICE-ASSISTED MONITORINGeven if weight is measured regularly, weight gain may be a

late sign of peripheral edema rather than an early sign of pulmo-nary congestion. Many episodes of worsening cHF do not appear to be associated with weight gain, and therefore, telemonitoring of weight alone may not be effective for early recognition of decom-pensation.24 A more sensitive indicator of early fluid accumulation and pulmonary congestion could reduce clinical decompensation. implanted devices provide a new source for continuous monitor-ing of physiologic parameters that may allow for the more timely recognition of serious arrhythmias, device problems, or worsening cHF. implanted devices that can be interrogated remotely include: pacemakers, implantable cardioverter-defibrillators (icDs), cardiac resynchronization therapy (cRt) devices, implantable loop record-ers, and implantable hemodynamic monitors.25

Remote Monitoring in Patients With Pacemakers and ICDs

in the United States, remote monitoring of devices was intro-duced by Medtronic in 2002 with the launch of their carelink Net-work. though this was initially designed for the remote follow-up of icD only, subsequent remote follow-up of pacemakers also became available. table 2 lists the various remote monitoring network systems available for implanted cardiac devices in the United States. these systems could be used for remote follow-up, remote monitoring, or patient-initiated transmissions. Remote follow-up is a program-mable scheduled transmission in which routine device parameters are collected remotely in a format similar to that obtained during a clinic visit. information obtained from the data repository is encoded in such a way that could be interfaced with commercially available device follow-up software. As opposed to trans-telephonic monitoring, prac-tically all information available through the face to face interrogation with a programmer can be obtained remotely. Remote monitoring refers to data acquired automatically, with unscheduled transmissions of any prespecified alerts related to device functioning or to clinical events. Patient initiated interrogation is a nonscheduled follow-up interrogation as a result of a patient experiencing a real or perceived clinical event, for which the patient is seeking expert evaluation.

FIGURE 1. Telemonitoringofchronicheartfailure.Evenbeforesymptomsdevelop,wirelesslycollectedhemodynamicdatacanbesenttoaclinicianforrevieworpersonalizedtreatmentrecommendationscanbeautomaticallygeneratedonthebasisofaprespecifiedalgorithm.ReprintedfromJ Am Coll Cardiol.2012;59:97104.HFindicatesheartfailure.

2013 Lippincott Williams & Wilkins www.cardiologyinreview.com | 143

Cardiology in Review Volume21,Number3,May/June2013 Remote Patient Monitoring in Chronic Heart Failure

TABLE 1. MajorClinicalTrialsonRemotePatientMonitoring

Study (Date) Methodology Patient CharacteristicsNo. of

Patients Follow-up Findings

Riegel et al5 (2002)

StS Patients discharged from hospital with HF, mean age 74 years, 49% men

358 6 months lower HF hospitalization days, Mean 1.1 vs 2.1, P = 0.05. inpatient HF costs were 45.5% lower at 6 months (P = 0.04).

Goldberg et al6 wHARF trial (2003)

tM Hospitalized patients NYHA class iii-iv, with a eF



Identification of Hardware Problems in Pacemakers and ICDs

Many current pacemakers and icDs are able to automatically execute periodic testing of battery status, lead impedances, or sens-ing and capture thresholds. this information can then be sent from the patients home to the physician using a transmitter, thus avoiding an unnecessary office visit. the clinical value of remote monitoring using wireless icDs was evaluated recently in the lumos-t Safely Reduces Routine Office Device Follow-Up (tRUSt) trial.26 A total of 1339 patients were randomized in a 2:1 fashion to remote moni-toring or conventional follow-up. Remote monitoring reduced total in hospital device evaluations by 45% without affecting morbidity. Median time to evaluation was less than 2 days in the remote monitor-ing group as compared with 36 days in the conventional group (P < 0.001) for all arrhythmic events. the clinical evaluation of Remote Notification to Reduce time to clinical Decision (cONNect) trial was a multicenter, prospective, randomized trial involving 1997

patients that examined the utility of wireless remote monitoring with automatic clinician alerts.27 After 15-month follow-up, there was a significant decrease in the time from event occurrence to clinical deci-sion in the remote monitoring arm versus the control arm (4.6 vs 22 days; P < 0.001). there was also a significant decrease in mean length of stay per hospitalization visit in the remote monitoring arm (3.3 vs 4 days; P = 0.002).27 Over the last several years, there have been a number of well-publicized icD lead failures from several manufac-turers.28,29 Due to their more complex design using separate conductor wires and electrodes, defibrillator leads are more susceptible to failure than pacemaker leads. Remote follow-up may be particularly useful for early identification of lead failure manifested by oversensing of noise artifacts, abrupt rise in pacing impedance, or both. early and reliable detection of icD lead failure can prevent delivery of inap-propriate or ineffective therapies, reduction in the risk of inappropri-ate shock-related hospitalization, and improved battery longevity.30 in the tRUSt trial, remote monitoring detected generator and lead

FIGURE 2. Thecircleofhomemanagementofheartfailurecontainsthefollowingelements:homemeasurementofphysiologicalinformation,transmissionofdata,processingofdatabyqualifiedpersonnel,timelyinterventionbycontactingthepatient,reassess-mentandfollow-uptoconfirmimprovementinclinicalstatus.ReprintedfromfromreferenceN Engl J Med.2010;363:23642367.

chaudhry et al20 (2010), tele-HF study

tM Patients recently hospitalized for HF, median age 61 years; 48% men, 39% black.

1653 6 months No differences in composite of death and readmission (52.3% vs 51.5%; P = 0.75) or mortality (11.1% vs 11.4%; P = 0.88).

Koehler et al 21 (2011), tiM-HF study

tM Stable ambulatory patients with HF NYHA class ii/iii with eF 35% and a history of HF decompensa-tion within the previous 2 years or with eF 25%.

710 26 months No significant effect on all-cause mortality (HR, 0.97; 95% ci, 0.671.41; P = 0.87) or on cardiovascular death or HF hospitalization (HR, 0.89; 95% ci, 0.671.19; P = 0.44).

cHAt study indicates chronic Heart Failure Assistance by telephone Study; ci, confidence interval; DiAl, Randomized trial of Phone intervention in chronic Heart Failure; eF, ejection fraction; HF, heart failure; HR, hazard ratio; HFHc trial, Heart Failure Home care trial; HHH study, Home or Hospital in Heart failure study; lv, left ventricular; NYHA, New York Heart Association; Pe, pulmonary edema; RR, relative risk; StS, Structured telephone Support; tele-HF, telemonitoring to improve Heart Failure Outcomes; teN-HMS, trans-european Network-Home-care Management System; tiM-HF, telemedical interventional Monitoring in Heart Failure; tM, telemonitoring; wHARF trial, weight Monitoring in Heart Failure trial.

TABLE 1. (Continued)

Study (Date) Methodology Patient CharacteristicsNo. of

Patients Follow-up Findings



problems earlier than conventional scheduled follow-ups (1 vs 5 days; P = 0.05). A total of 20 device problems requiring surgical revision (0.012 per patient-year) were found, 15 in the remote monitoring group and 5 in the conventional group.31

in a study of 81,081 patients on the AltitUDe remote moni-toring system (Boston Scientific, Natick, MA), a random sample of 2000 patients having 5279 shock episodes was selected.32 episodes were classified as appropriate (70%) or inappropriate (30%) icD therapies. there was substantial inter-reviewer agreement for rhythm classification, especially for dual-chamber devices, indicating their diagnostic value in rhythm interpretation.32 in the AltitUDe sur-vival study, patients with the device receiving network monitoring and follow-up (n = 69,556) had significantly higher 1- and 5-year survival rates as compared with those who received device follow-up in clinics only (n = 116,222 patients; 50% reduction; P < 0.0001).33

Other Physiologic and Hemodynamic Parametersvarious parameters that can be monitored in patients with

icDs and cRts include patient activity level, nocturnal heart rate, heart rate variability (HRv), intrathoracic impedance, arrhythmias, and appropriate versus inappropriate shocks. Decreased patient activity level, as measured by integrated accelerometers, can pre-dict clinical decompensation of cHF. HRv represents the balance between the sympathetic and parasympathetic outflow to the heart, and low HRvindicative of high sympathetic and low parasym-pathetic activityprovides prognostic information in patients with cHF. continuous HRv can be measured as the standard deviation of 5-minute median atrial-atrial intervals (SDAAM) sensed by the device.34 SDAAM less than 50 ms, when averaged over 4 weeks, was associated with an increased risk of mortality (HR, 3.20; P = 0.02). A decline in SDAAM was 70% sensitive in detecting cardiovas-cular hospitalization, with 2.4 false-positives per patient-year of follow-up.34

intrathoracic impedance is the resistance measured between the right ventricular lead tip and the pulse generator of the device. the impedance can be measured by delivering a small alternating current between the lead and the device. the Medtronic impedance Diagnostics in Heart Failure Patients trial (MiDHeFt) showed that an increase in pulmonary vascular congestion leads to decreased impedance, which usually precedes clinical decompensation of cHF (Fig. 3).35 intrathoracic processes, such as pneumonia or pleural

TABLE 2. ComparisonofRemoteMonitoringSystemsinImplantableDevices

Biotronik Boston Scientific Medtronic St. Jude

Network monitoring Home Monitoring latitude carelink Merlin.net

wireless communication Radiofrequency Radiofrequency Radiofrequency Radiofrequency

Data transmission GSM Phoneline Phoneline and GSM Phoneline or GSM

Physician notification SMS, e-mail, fax Fax, phone SMS, e-mail SMS, e-mail, fax

Feedback to patient leD indicating normal status or call to clinic

Automatic text and audio messages

confirmation for successful interrogation and transmission

leD indicating call to clinic, automated phone calls

intracardiac electrograms (at real-time follow-up)

30 s 10 s 10 s 30 s

intracardiac electrograms (arrhythmic episodes)

All episodes stored in memory All episodes stored in memory

All episodes stored in memory All episodes stored in memory

Special features Automatic Rv and lv thresholds.comprehensive heart failure monitor, intrathoracic impedance measurement

Optional wireless weight scales and blood pressure cuffs

Automatic Rv, and lv (consulta and Protecta Xt) pacing thresholds.Optivol lung fluid status alert.Remote monitoring of implantable loop recorders

Automatic Rv, and lv pacingthresholds.coRvUe fluid status alert.

GSM indicates global system for mobile communications; leD, light-emitting diode; lv, left ventricle; Rv, right ventricle; SMS, short message service.Adapted from Am J Manag Care 2008;14:106115.

FIGURE 3.A,Relationshipbetweenintrathoracicimpedance,PCWP,andnetfluidloss(I/O)during4daysofintensivediuresisinthecardiaccareunit(CCU).B,Pooleddatafrom5patientsofarelationshipbetweenintrathoracicimpedanceandPCWPduringintensediuresisintheCCU.AdaptedfromCirculation2005;112:841848.PCWPindicatespulmonarycapillarywedgepressure.



effusion, can affect the accuracy of intrathoracic impedance mea-surements. edema in the device pocket caused by postsurgical edema and inflammation can lower the impedance measurements and may not reliably indicate worsening pulmonary congestion. the Optivol algorithm from Medtronic tracks a patients fluid status over time and provides an insight into whether the patient is trending toward a wet or dry state. As per this algorithm, impedance is measured every 20 minutes from noon to 5 pm for a total of 64 measurements over a 5-hour period. the average of these 64 measurements is reported by the device as the daily impedance value. Averaging impedance mea-surements over a 5-hour period minimizes the effects of respiration and posture on serial daily measurements. the Fluid Accumulation Status trial (FASt) prospectively followed 156 patients with chronic HF to study the relative sensitivity and unexplained detection rate of changes in body weight or Optivol fluid index to predict cHF exacerbation.36 true positives were defined as episodes of worsen-ing HF occurring within subsequent 30 days of a fluid index above threshold or an acute weight gain of 3 lbs in 1 day or 5 lbs in 3 days. Unexplained detections were defined as threshold crossings or acute weight gains not associated with worsening HF. Sensitivity was greater (76% vs 23%; P < 0.0001) and unexplained detection rate was lower (1.9 vs 4.3/patient-year; P < 0.0001) for Optivol fluid index than for acute weight changes.36

in a large prospective trial of 532 patients with cHF who underwent cRt,37 audible alert was turned ON in 430 (81%) patients and OFF in 102 (19%) patients. After 11-month follow-up, hospitalization for cHF occurred in 29 patients in the ON group, and 20 patients in the OFF group (7% vs 20%; P < 0.001). the rate of combined cardiac death and cHF hospitalization was lower in the ON group (log-rank test; P = 0.007). However, in the Diagnostic Outcome trial in Heart Failure (DOt-HF)38 of 335 patients with cHF who had icDs implanted, routine measurement of intrathoracic impedance with an audible patient alert resulted in increased HF hospitalizations (HR, 1.79; 95% ci, 1.082.95; P = 0.022), and increased outpatient visits (250 vs 84; P < 0.0001), whereas the number of deaths was comparable (19 vs 15; P = 0.54). the Optivol fluid index has low sensitivity and positive predictive value in the early period after implantation of a device to predict HF exacerbation. However, sensitivity improved within the first 6 months after implant.39 Although regular measurement of impedance might allow early detection of HF decompensation, and could poten-tially help avoid rehospitalization, data from large trials have yielded conflicting results. the Optimization of Heart Failure Management using Optivol Fluid Status Monitoring and carelink (Optilink HF) study40 is designed to investigate whether early detection of conges-tion using Optivol reduces mortality and cardiovascular hospital-ization in patients with cHF. Recruitment to this trial is currently ongoing, and preliminary results are expected by 2014. implanted devices can detect subclinical episodes of rapid atrial rate, which can give an estimate of their thromboembolic risk and guide treatment decisions. in a prospective observational study of patients with or without prior atrial fibrillation (AF), with one or more stroke risk fac-tors, (diabetes, hypertension, cHF, prior stroke, or transient ischemic attack, and age >65 years) receiving pacemakers or defibrillators,41 atrial tachycardia (At)/AF burden was monitored. At/AF detection was programmed to atrial rate more than 175 bpm lasting longer than 20 seconds. the aim of this study was to begin to understand the rela-tionship between device-detected episodes of At/AF and the risk for thromboembolic events. During a mean follow-up of 1.4 years, annu-alized thromboembolic risk was 1.1% for zero-, 1.1% for low- (5.5 hours of At/AF in prior 30 days). As compared with zero bur-den, an adjusted HR in the high burden subset was 2.20 (0.965.05, P = 0.06).29 in a subsequent trial of 2580 patients, more than 65

years of age, with hypertension and no history of AF, who underwent pacemaker or icD,42 episodes of subclinical atrial tachyarrhythmias (atrial rate >190 bpm for >6 minutes) were monitored for 3 months and patients followed for a mean of 2.5 years. By 3 months, sub-clinical atrial tachyarrhythmias had occurred in 261 patients (10.1%) and were associated with a significantly increased risk of ischemic stroke or systemic embolism after adjustment for predictors of stroke (HR, 2.50; 95% ci, 1.284.89; P = 0.008). thus, device-detected At/AF episodes, though subclinical, are associated with a higher risk of stroke, and anticoagulation should be strongly considered in patients with high At/AF burden.

the use of multiple parameters may improve the ability to identify patients at risk of HF events, beyond the use of intratho-racic impedance alone. the Program to Access and Review trend-ing information and evaluate correlation to Symptoms in Patients with Heart Failure (PARtNeRS HF) study43 was a prospective, multicenter, observational study of 694 patients who received cRt-icD for HF. in an effort to improve the predictive value of these impedance measures, the authors devised an algorithm that com-bined impedance data with prospectively identified criteria: a fluid index more than 100 or any 2 of the following criteria met during a 1-month period: long AF duration, rapid ventricular rate during AF, fluid index more than 60, low patient activity, high night HR, low HRv, low cRt pacing, or icD shocks. After 11.7 2 months of fol-low-up, 90 patients had 141 adjudicated hospitalizations for decom-pensated cHF. Patients with positive combined device diagnostics had a 5.5-fold increased risk of hospitalization for cHF within the subsequent 30 days (HR, 5.5; 95% ci, 3.48.8; P < 0.0001), and the risk remained high after adjusting for clinical variables (HR, 4.8; 95% ci, 2.98.1; P < 0.0001).43

Implantable Hemodynamic MonitorsAcute decompensation in both systolic and diastolic HF was

preceded by a significant increase in end-diastolic pressures, which occurred at least 2 weeks before hospitalization for cHF.44 As hemo-dynamic decompensation precedes clinical decompensation in these patients, frequent monitoring of hemodynamic parameters may detect early signs of an exacerbation, enabling timely treatment inter-ventions aimed at avoiding hospitalizations. improvements in tech-nology have allowed the development of implantable hemodynamic sensors that are particularly promising. they provide a convenient and continuous platform for monitoring hemodynamics. Several sys-tems are under development that measure pressures directly in the right ventricle (Rv), left atrium (lA), and pulmonary artery (PA).

Right Ventricular Pressure SensorDecompensated HF is preceded by significant changes in

intrathoracic impedance and Rv pressures during the month before a major clinical event. the chronicle implantable Hemodynamic Monitor (chronicle, model 9520; Medtronic, Minneapolis, MN) is a long-term implanted device designed to continuously record Rv pressures, and pressure derivatives (Fig. 4).45 the device is similar in appearance to the pulse generator of a pacemaker, and is implanted subcutaneously in the pectoral area with a modified unipolar trans-venous pacemaker lead carrying a pressure sensor in the Rv out-flow tract. the pressure sensor capsule is located 3 cm proximal to the tip and includes a deflectable titanium diaphragm. Motion of this diaphragm changes capacitance and thereby reflects changes in Rv pressure. Digital sampling is used to construct continuous pres-sure waveforms for storing hemodynamic information. the device is capable of continuously measuring and storing heart rate, body tem-perature, patient activity, continuous pressure trends, as well as spe-cific triggered events such as bradyarrhythmias, tachyarrhythmias, or patient-activated episodes. the Rv pressure at the time of depolariza-tion is recorded as Rv diastolic pressure. An estimate of PA diastolic



pressure is measured at the time of maximum positive rate of change in Rv systolic pressure (dP/dt), corresponding to the pulmonic valve opening. Rv systolic pressure is measured at the peak of the Rv pres-sure waveform.

A preliminary study on 32 patients with cHF showed a favorable impact of this device on hospitalizations for cHF.46 the chronicle Offers Management to Patients with Advanced Signs and Symptoms of Heart Failure (cOMPASS-HF) trial was the first randomized, prospective trial examining implantable hemodynamic monitoring in cHF.46 this was a single-blind, parallel-controlled trial that randomized 274 patients with New York Heart Association (NYHA) function class iiiiv HF on optimal medical therapy to receive the chronicle device (n = 134) versus standard therapy (n = 140). Patients with severe lung disease, kidney disease (serum creati-nine >3.5 mg/dl or chronic renal dialysis), PA hypertension, known atrial or ventricular septal defects, tricuspid or pulmonary stenosis, mechanical right heart valves, or a severe, noncardiac condition limiting 6-month survival were excluded. Primary end points of the study included freedom from system-related complications, freedom from pressure sensor failure, and reduction in the rate of cHF-related events (hospitalizations or emergency visits). At 6-month follow-up,

the complication-free rate was 91.5%. A total of 84 HF-related events occurred in 44 patients in the chronicle group as compared with 113 events in 60 patients in the control group (0.67 vs 0.85; P = 0.33). A retrospective analysis showed a 36% reduction in the relative risk of a cHF-related hospitalization in the chronicle group (HR, 0.64; 95% ci, 0.420.96; P = 0.03). incorporation of this exciting technology into standard pacing or defibrillator leads would be more practical and acceptable, and holds promise for the future.

Pulmonary Artery Pressure Sensorthe Pulmonary Artery Pressure Sensor is a novel catheter-

delivered pressure sensor that is chronically implanted in the PA through right heart catheterization (Fig. 5).47 the cardioMeMS heart sensor (champion; cardioMeMS, Atlanta, GA) consists of a wireless 3D coil and a pressure-sensitive capacitor covered with sili-cone. it contains nickel-titanium wire loops attached to each end that helps avoid distal migration. the device is 15-mm long and 3-mm wide and delivered through a catheter-based system from the femoral vein under fluoroscopic guidance. A selective angiography is done to confirm the correct position of the device and unimpeded blood flow distal to it. Alterations in PA pressure alter the baseline resonant frequency emitted by the device that is transduced into a real-time pressure waveform. the system is calibrated to account for changes in atmospheric pressure using a built-in sensor. the system contains no batteries or internal power source, but is instead powered by radio-frequency signals provided by the external antenna. Patients are con-tinued on warfarin therapy if previously indicated for other reasons, or placed on 30 days of dual antiplatelet therapy. the cardioMeMS Heart Sensor Allows Monitoring of Pressure to improve Outcomes in NYHA class iii Heart Failure Patients (cHAMPiON) trial was a prospective, multicentric, single-blind clinical trial conducted in the United States.48 the trial included 550 patients with NYHA class iii HF, irrespective of the left ventricular ejection fraction, with a previous hospital admission for HF. the patients were on standard drug and device therapy in accordance with the national guidelines. Patients were randomized to implantation of a cardioMeMS device (n = 270) versus conservative monitoring (n = 280) based on crude assessment of volume status (weight gain, clinical signs of volume overload based on physical examination and auscultation of the heart and lungs). the trial excluded patients with recurrent pulmonary embolism or deep vein thrombosis, cRt instituted within 3 months before randomization, and patients with estimated glomerular fil-tration rate



Left Atrial Pressure Sensorthe HeartPOD device (St Jude Medical, Minneapolis, MN)

has been developed to directly measure lA pressure, core tempera-ture, and intracardiac electrograms (Fig. 6).50 this device has a sen-sor lead placed intra-atrially through a transseptal puncture, which is then linked to a coil antenna placed subpectorally. the Hemodynami-cally Guided Home Self-therapy in Severe Heart Failure Patients (HOMeOStASiS) study was a prospective, observational, first-in-human study of a physician-directed patient self-management sys-tem using the HeartPOD device.50 Forty patients with NYHA class iii or iv HF (reduced or preserved left ventricular ejection fraction) on optimal medical therapy, with a minimum of one prior HF event requiring intravenous therapy were enrolled for the study. the device was implanted successfully in all patients. Four patients had device failure due to sensor malfunction, of which 3 underwent success-ful reimplantation and 1 declined. Patients received dual antiplatelet therapy with aspirin and clopidogrel for 6 months. if a patient was already on warfarin, then aspirin alone was added. During the first 3 months, patients and clinicians were blinded to lA pressure readings, and treatment was based on clinical status (observational period). this was followed by a 3-month titration period during which lA pressure-guided therapy was initiated with the goal of optimizing lA pressures. thereafter, patients entered the stability period where lA pressure readings were individualized for the patient. After a median follow-up of 25 months, lA pressure-guided physician-directed patient self-management was associated with improved control of lA pressures (17.614.8 mm Hg; P = 0.003), improvement in NYHA class (0.7 + 0.8, P < 0.001), more optimal neurohormonal antago-nist dosing (angiotensin-converting enzyme/angiotensin-receptor blockers uptitrated by 37%, P < 0.001; and -blockers uptitrated by 40%, P < 0.001), and a 59% reduction of clinical events in the titra-tion and stability period as compared with observation period (0.28 per year; 95% ci, 0.180.45 per year; P = 0.041).50 there were 2 late

ischemic strokes, one in a patient with left ventricular thrombus, and the other where the source could not be identified. Major limitations of this study include the small sample size, observational design, and lack of a true standard control group.

the left Atrial Pressure Monitoring to Optimize Heart Fail-ure therapy Study (lAPtOP-HF study) is an ongoing phase iii, randomized, open label trial of more than 700 patients with NYHA functional class iii HF (reduced or preserved ejection fraction), ran-domized to treatment arm versus control arm.51 Patients random-ized to the treatment arm will undergo placement of a stand-alone implantable lAP monitoring device or cRt-D device with an inte-grated lAP monitoring device, depending on their medical condi-tion. Outcomes studied will include a safety end point (freedom from procedure- or device-related major adverse cardiovascular and neurological events) and efficacy end point (HF hospitalization). the study is expected to be completed by August 2013.

implantable hemodynamic monitors provide us with the advantage of direct measurement of filling pressures, and have the potential to promote patient compliance through their active partici-pation in day-to-day management. However, this potential benefit must be weighed against the invasive nature of an implant with its attendant complications, such as bleeding, infection and thromboem-bolic events. Further studies are needed to identify the specific subset of patients, where benefit would outweigh these risks.

MEDICOLEGAL CONSIDERATIONSBefore the widespread use of remote monitoring technolo-

gies can be considered, a number of medicolegal concerns need to be addressed. the same fundamental legal principles of medicine should apply to the field of telecardiology. this includes informed consent, responsibility for medical care, confidentiality, physician licensing, and insurance-related issues. Before initiating telemonitor-ing, it is advisable to have the patient sign a written informed consent

FIGURE 5. TheCardioMEMSwirelesspulmonaryarterypressuresensor.A,Thewireloopspassivelypositionandholdstablethesensorwithinadistal,descendingbranchoftheleftorrightpulmonaryartery.B,Wirelessheartfailurepressuremonitoringsystemelectronicsandantenna(insideofpillow).C,Radiographofthesensorwithinthepulmonaryartery.ReprintedfromAm Heart J.2011;161:558566.



authorizing transmission of personal data to third parties, and stating the respect of privacy and confidentiality of patient data by device com-panies. it should be clearly stated that telemonitoring does not replace an emergency medical service. if there can be a delay in respond-ing to the alerts received during weekends or holidays, this should be mentioned in the consent form. Physician and patient responsibilities need to be defined in explicit terms. the degree of time delay from the physician in response to remotely obtained data that can be consid-ered to be within acceptable limits needs to be defined. in the United States, the Health insurance Portability and Accountability Act, the Health information technology for economic and clinical Health Act, and code of Federal Regulations provide guidelines addressing the security and privacy of Protected Health information. Unauthor-ized access to the remote monitoring database by hackers is of sig-nificant concern. they can retrieve encrypted personal patient data, and potentially reprogram device settings, which can in some cases be lethal. Database vulnerability will become an increasingly impor-tant issue as database size increases and providers rely more heavily on database information. Potential licensing issues could arise with physicians who are monitoring patients in states where they are not licensed to practice. in a survey that evaluated health-care providers to determine their willingness to use remote monitoring, clinicians cited several concerns, especially medicolegal implications and lack of remuneration for potentially increased clinical workload due to telephone interactions with patients.52

FINANCIAL CONSIDERATIONStelemonitoring technologies pose a significant economic bur-

den on an already high-cost health-care system. the lack of appro-priate reimbursement for telemonitoring services is a major concern today in many countries. in January 2009, the United States centers for Medicare and Medicaid Services afforded favorable financial reimbursement to physicians who manage device patients remotely. Monthly reimbursement is available for remote monitoring of an implantable cardiovascular monitor system, either a stand-alone device or one that is incorporated into a pacemaker or icD. there is a lack of prospectively and uniformly collected economic data on the effectiveness of various remote monitoring systems. Studies have shown conflicting results and inconsistent benefits. However, at least for pacemakers and icDs, replacement of calendar-based office fol-low-ups with remote follow-up and monitoring can increase patient safety by early detection of medical and technical events, reduce the number of in-office follow-ups, and reduce length of stay and hospi-talization rates. in the United States, great emphasis is placed on the reduction of readmission rates because these have important implica-tions for the reimbursement of hospitals caring for patients with HF.

there is an impetus at the national level to incorporate an electronic Medical Record (eMR) into our health care. Any attempt to integrate remote follow-up and monitoring data into an eMR necessitates that a specific interface be written between each vendor website and the particular eMR system that would enable a bidirec-tional communication and data exchange between them.

CONCLUSIONin the United States, clinical experience with telemonitoring is

still in its infancy. telehealth will enable many more patients to enjoy the standard of care available only to a select few at the moment. continuous monitoring might improve patient compliance and adher-ence to medication and other guideline-recommended therapeutic measures that are known to be associated with a decrease in clini-cal events. telemonitoring may be difficult to use for some patients due to the lack of visual acuity or manual dexterity.53 clinicians may also be overwhelmed by information from telemonitoring, leading to noncompliance by health-care professionals. various medicolegal and financial hurdles need to be overcome before its widespread use. However, telemonitoring has the potential to actively engage the larg-est health-care workforce in the worldpatients and their families.

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FIGURE 6. TheHeartPODleftatrialpressuremonitoringsystem.A,Photographsshowingtheimplantableportionofthesystemcomprisingthesensorleadandcoilantenna.Amagnifiedviewofthesensormodule(inset)showsthesensingdiaphragmandseptalanchor-fixationsystem.B,Photographofthepatientadvi-sormoduleusedbypatientstocommunicatewiththeimplant-edsensorlead.C,Chestradiographofapatientimplantedwiththemonitoringsystemfromtheleftaxillaryvein.Thepatienthadanexistingdual-chamberICDgeneratorwithrightatrialandrightventricularpacing/defibrillationleads.ReprintedfromCirculation2010;121:10861095.ICDindicatesimplantablecardioverter-defibrillators;CAindicatescoilantenna;RA,rightatrium;RV,rightventricle;SM,sensormodule.



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Remote Patient Monitoring in Chronic Heart Failure