Risk of Proarrhythmic Events in the AtrialFibrillation Follow-up Investigation of RhythmManagement (AFFIRM) Study

Kaufman ES, Zimmermann PA, Wang T, et al. J Am Coll Cardiol2004;44:1276 – 82.

Study Question: When appropriate safety guidelines are em-ployed, what is the risk of proarrhythmia from drug treat-ment of atrial fibrillation (AF)?Methods: In the AFFIRM study, 2033 patients were ran-domly assigned either to treatment with a class I or IIIantiarrhythmic drug. Proarrhythmic events were analyzedin retrospective fashion.Results: Among 1047 patients treated with quinidine, pro-cainamide, disopyramide, sotalol, ibutilide, or dofetilidethe cumulative incidence of ventricular proarrhythmicevents at 5 years of follow-up was 5%. Independent predic-tors of ventricular proarrhythmia were age �65 years (oddsratio [OR] 2.0), a history of congestive heart failure (OR2.7), and mitral regurgitation (OR 2.0). The incidence oftorsade de pointes was 1.0% in women and 0.4% in men.Most patients with torsade de pointes also had bradycardia,hypokalemia or hypomagnesemia.Conclusions: When safety guidelines such as appropriatepatient selection criteria and dose adjustments based onhepatic or renal function are followed, the risk of proar-rhythmia during drug therapy of AF is low.Perspective: A problem with this study is that the criteria foridentification of ventricular proarrhythmic events were notspecified. While torsade de pointes usually is readily iden-tifiable as a proarrhythmic event, other forms of proar-rhythmia may be difficult to distinguish from a first arrhyth-mia. In any case, the low incidence of torsade de pointes isreassuring. FM

Rate Control Is More Cost-Effective Than RhythmControl for Patients With Persistent AtrialFibrillation—Results From the Rate Control versusElectrical Cardioversion (RACE) StudyHagens VE, Vermeulen KM, TenVergert EM, et al. Eur Heart J2004;25:1542–9.

Study Question: In patients with persistent atrial fibrillation(AF), is a rate-control strategy less expensive than a rhythm-control strategy?Methods: The direct medical and nonmedical costs wereevaluated in 428 patients (mean age 69 years) with persis-tent AF who were randomly assigned to rate control(n�206) or rhythm control with cardioversion plus antiar-rhythmic drug therapy (n�222). The mean duration offollow-up was 2.3 years.

Results: The total cost was 7386 euros in the rate-controlarm. The total cost was 12% higher in the rhythm-controlarm, owing to the costs of cardioversions, hospitalizations,and antiarrhythmic drug therapy. Cost was highest inwomen, in older patients, and in patients with structuralheart disease. The presence of sinus rhythm at the end of thestudy did not influence cost.Conclusions: A rate-control strategy is less expensive than arhythm-control strategy in patients with persistent AF.Perspective: RACE, along with other clinical trials such asAFFIRM, showed that a rhythm-control strategy does notimprove quality-of-life or survival compared to a rate-con-trol strategy in older patients with AF. The present studydemonstrates an economic advantage that favors rate con-trol. However, most of the subjects in the study were olderpatients without severe symptoms. It should be noted thatregardless of cost, rhythm control (either with antiarrhyth-mic drugs or catheter ablation) often is the strategy ofchoice for symptomatic patients who do not respond well torate-control therapy. FM

Flecainide Versus Ibutilide for ImmediateCardioversion of Atrial Fibrillation of Recent Onset

Reisinger J, Gatterer E, Lang W, et al. Eur Heart J2004;25:1318 –24.

Study Question: Are flecainide and ibutilide equally effica-cious when used to convert atrial fibrillation (AF)?Methods: This was a multicenter, single-blind, randomizedcomparison of intravenous (IV) flecainide (2 mg/kg over 20min, n � 101) and ibutilide (1 mg over 10 min, with thesame dose 10 min later if needed, n � 106) in patients withAF of 1–48 h duration. The primary end point was conver-sion to sinus rhythm within 90 min of the onset of druginfusion.Results: The mean age of the patients was 63 years, themedian duration of AF was 12 h, and 20% of patients hadidiopathic AF. No significant difference existed in the pro-portion of patients who converted to sinus rhythm within90 min after infusion of flecainide (56%) and ibutilide(50%). The incidence of torsade de pointes was 1% in theibutilide group, but there was no significant difference inthe overall incidence of adverse events between the twogroups (flecainide, 12%; ibutilide, 7%). The mean drugcost/patient was 7.3 euros in the flecainide group, com-pared to 208 euros in the ibutilide group.Conclusions: Intravenous flecainide and ibutilide have equalefficacy and safety when used to convert AF.Perspective: If transthoracic cardioversion becomes neces-sary because of failed pharmacologic cardioversion, ibutil-ide has two advantages over flecainide: 1) it lowers thedefibrillation threshold and 2) it suppresses immediaterecurrences of AF. However, these advantages may notjustify the use of ibutilide given that it is almost 30 timesmore expensive than IV flecainide. In any case, IV flecainide

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ArrhythmiasAbstracts

is not available in the United States. It would be interestingto compare ibutilide to single-dose oral flecainide for acuteconversion of AF. FM

Left Atrial Tachycardia After CircumferentialPulmonary Vein Ablation for Atrial Fibrillation.Electroanatomic Characterization and Treatment

Mesas CE, Pappone C, Lang CCE, et al. J Am Coll Cardiol2004;44:1071–9.

Study Question: What are the characteristics of left atrialtachycardias that occur as a complication of catheter abla-tion of atrial fibrillation (AF)?Methods: This study describes 14 left atrial tachycardias orflutters that occurred in 13 patients who underwent cir-cumferential pulmonary vein ablation (CPVA) for paroxys-mal or chronic atrial fibrillation (AF). These patients com-prised 5% of the total population of patients whounderwent CPVA. Radiofrequency catheter ablation wasperformed after detailed electroanatomic mapping.Results: Left atrial tachycardia/flutter first occurred 1–6months after CPVA and was incessant in 10 patients. Therewere 3 focal atrial tachycardias (mean cycle length 266 ms)arising near a pulmonary vein, and 11 macroreentrant leftatrial flutters (mean cycle length 275 ms), utilizing themitral isthmus, posterior wall, or a gap in a previous abla-tion line. Catheter ablation was successful in eliminating 13of the 14 atrial arrhythmias, with no recurrences over amean of 2.5 months of follow-up.Conclusions: Either focal atrial tachycardia or macroreen-trant atrial flutter may occur up to several months afterCPVA. Successful catheter ablation of these arrhythmiasusually can be achieved.Perspective: Left atrial flutter is a common manifestation ofproarrhythmia after left atrial ablation of AF. In this study,the incidence of atrial tachycardia/flutter after AF ablationwas only 5%. In other studies, the incidence has been10–20%. An important point not made in this study is thatmany of the macroreentrant atrial flutters that occur afterleft atrial ablation of AF resolve spontaneously during 3–6months of follow-up, presumably because of lesion matu-ration and scar remodeling that eventually eliminate proar-rhythmic gaps in the ablation lines. FM

Non-Contact Mapping to Guide RadiofrequencyAblation of Atypical Right Atrial FlutterTai CT, Liu TY, Lee PC, Lin YJ, Chang MS, Chen SA. J Am CollCardiol 2004;44:1080 – 6.

Study Question: What are the characteristics and response toablation of nonincisional atypical right atrial flutter (AFl)?Methods: This study describes atypical right AFl that oc-curred in 15 patients (mean age 61 years) without a historyof heart surgery. Ten patients had no heart disease and 11had already undergone catheter ablation of typical AFl. A

3-dimensional noncontact mapping system was used todelineate the flutter circuits and to guide radiofrequencycatheter ablation.Results: The mean AFl cycle length was 210 ms. There wassingle-loop reentry utilizing a channel between the crista ter-minalis (CT) and an area of functional block in the anterolat-eral right atrium in 7 patients. Eight patients had double-loopreentry utilizing either a gap in the CT or a free-wall channel.Linear radiofrequency ablation across the CT gap or free-wallchannel�the cavotricuspid isthmus was successful in elimi-nating recurrences of the right AFl in 13 patients (87%) duringa mean of 17 months of follow-up.Conclusions: Nonincisional, atypical right AFl may becaused by either single- or double-loop reentry and usuallyis amenable to radiofrequency ablation.Perspective: This study very nicely delineates a relativelyunusual form of AFl. Most atypical right AFls are incisionalor scar-related. The present study is the largest collection todate of atypical right AFls that were not incisional. Thesophisticated noncontact mapping system used in thisstudy is helpful in delineating the reentry circuits, butsimple entrainment mapping also can be used to identifycritical components of the reentry circuit that may be effec-tive ablation sites. FM

Effect of Isthmus Anatomy and Ablation Catheteron Radiofrequency Catheter Ablation of theCavotricuspid Isthmus

DaCosta A, Faure E, Thevenin J, et al. Circulation2004;110:1030 –5.

Study Question: In patients with typical atrial flutter (AFl),what is the impact of cavotricuspid isthmus (CTI) anatomyand type of ablation catheter on the duration of radiofre-quency ablation?Methods: Right atrial angiography was performed in 185patients (mean age 67 years) with AFl. The CTI was mea-sured and characterized as straight, concave, or pouch-like.When the CTI was short (�35 mm), ablation was per-formed with an 8-mm-tip catheter. When the CTI was long(�35 mm), the patient was randomly assigned to ablationwith an 8-mm- or irrigated-tip catheter.Results: The CTI was short in 123 patients and long in 62patients. Its morphology was straight in 58% of patients,concave in 24%, and pouch-like in 18%. Complete CTIblock was achieved in 99% of patients. The amount ofradiofrequency energy was significantly less for short (10 min)than for long (19 min) CTIs. When the CTI was long, therewere no differences in procedural parameters between the8-mm- and irrigated-tip catheters. Significantly less abla-tion was needed to achieve block when the CTI was straightthan when it was concave or pouch-like.Conclusions: The amount of radiofrequency ablationneeded to achieve complete CTI block is influenced by the

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