RWC Physicians’ Conference

Evaluation of Suspected CAD in 2011

Nader M. (Nader) Banki, MD

Xiushui (Mike) Ren, MD March 4, 2011

Disclosure of Relevant Financial Relationships

Under the ACCME Standards for Commercial Support, everyone who is in a position to control the content of an education activity must disclose all relevant financial relationships with any commercial interest. A “commercial interest” includes any proprietary entity producing health care goods or services, with the exemption of non-profit or government organizations and non-health care related companies. A financial relationship is relevant if it pertains to the activity’s content matter including any related health care products or services to be discussed or presented.

Drs. Banki and Ren have disclosed that they have no relevant relationships with commercial or industry organizations. The CME Department has reviewed their disclosure information for the planner(s) and/or committee/faculty for this program and they do not have relationships that present a relevant conflict of interest.

Outline

Indications for

“stress testing”

Contraindications

Testing modalities

Including CTA

Test selection

Cases

Indications

Suspected CAD Pre-operative

Pulmonary hypertension

DOE

Valvular heart disease

Viability

Risk stratification

Indications: Suspected CA

Bayes’ Theorem

Indications: Suspected CA

Indications: Suspected CA

Contraindications

Evaluation of Suspected CAD

(symptomatic)

Treadmill ECG

Stress Echo Exercise

Dobutamine

Myocardial perfusion (nuclear) Exercise

Persantine

CTA

Coronary angiography (invasive)

Evaluation of Suspected CAD

Functional: Treadmill ECG

Stress Echo

Myocardial perfusion

Anatomic CTA

Coronary angiography

Treadmill ECG

Exercise: preferred if possible Treadmill

Good for detecting ischemia and arrhythmia

Cheap

Readily available

Treadmill ECG

Stress Echo and Outcomes

Stress Echo

MPI and Outcomes

MPI

MPI

Test Performance

Stress echo: Sensitivity = 85%

Specificity = 77%

Stress MPI: Sensitivity = 87%

Specificity = 64%

Bayes’ Theorem

The probability of a patient having the

disease after a test is performed depends

on pretest probability and the test

characteristics

Bayes’ Theorem

Bayes’ Theorem

Bayes’ Theorem

Bayes’ Theorem

Use Clinical Judgment!

RWC Case #1

56 year old female with a history of hypertension, dyslipidemia, fibromyalgia and chronic L-sided upper chest pain who reports 3 months mid-chest burning with exertion.

What is her pre-test probability of obstructive CAD?

Bayes’ Theorem

RWC Case #1

Treadmill Test:

6:55 Bruce Protocol

chest burning at peak exercise

1mm horizontal ST depression

Invasive Coronary Angiography

Invasive Coronary Angiography

RWC Case #2

43 y.o. woman without CAD risk factors

presents with 2 week history of sharp

chest pain lasting 1-2 min

ECG is normal

What is the pre-test probability?

Bayes’ Theorem

RWC Case #2

Treadmill test: 8 min on Bruce protocol

Borderline ST depressions

Equivocal test

Stress thallium was (-) for ischemia

RWC Case #3

43 year old male smoker with h/o dyslipidemia presents to ED with 1-2 week history of chest pain with and without exertion

Ruled out for MI in ED, EKG normal

What is his pre-test probability of obstructive CAD?

Bayes’ Theorem

RWC Case #3

Same-day treadmill test

4:20 seconds Bruce Protocol (7.0 METs)

118 bpm (66% of MPHR)

Normal blood pressure response

Chest pain after 2 minutes

No ischemic ST-T changes were noted

Referred for CT angiogram

Coronary CT Angiography

LV

RV

LAD

Invasive Coronary Angiography

Cardiac CT Invasive Angiography

RWC Case #3

PCI of the LAD

Coronary CT Angiography

Non-invasive diagnostic imaging test using CT technology and contrast to diagnose the presence and severity of coronary artery disease

Significant improvement in diagnostic accuracy because of increase in detector rows from 4 to 16 to 64

High negative predictive value (NPV)

Coronary CT Angiography

28 studies (>2,400 patients) evaluating the sensitivity and specificity coronary artery disease (>50% stenosis) in CTA when compared with coronary angiography

Sensitivity: 99%

Specificity: 89%

PPV: 93%

NPV: 100%

Mowatt G., Heart 2008 94; 1386-1393

Coronary CT Angiography

Indications:

Equivocal stress test

Symptomatic patients with an intermediate probability of obstructive CAD

Young patient prior to valve surgery

Anomalous coronary artery

Avoid when:

No symptoms

CKD (GFR<60)

Atrial fibrillation or frequent PAC’s/PVC’s

Pregnant

Dye hypersensitivity

Coronary CT Angiography

Experience at Kaiser RWC

64 slice CT scanner

First CTA in 2007

>200 CTA’s performed

Preparation:

Renal Function <30 days prior to scan

Hold Metformin 48 hours prior

Metoprolol 25mg the night before and 50mg morning of scan

Prior to Scan

18 gauge iv started in antecubital vein of L arm

+/- iv metoprolol at time of scan

SL NTG

90 cc of contrast

Coronary CT Angiography

>9,000 patients who underwent coronary CTA Followed for 20 months

Endpoints

Major adverse cardiac events

Death

MI Revascularization

Coronary CTA- Prognosis

Radiation Exposure

Experimental and epidemiologic evidence show strong link between low-dose ionizing radiation and solid cancers and leukemia

Medical uses of radiation are the largest source exposure to public

Measured in sieverts (Sv)

Unit of ionizing radiation absorbed

Attempts to reflect the biological effect rather than the physical aspects

Background radiation in one year (3mSv)

Radiation

Retrospective study of >950,000 patients enrolled in United Health Care

Utilization data were used to estimated:

cumulative effective dose

3 year study period

NEJM 2009;361:849-57

Radiation

Background Radiation:

3 mSv/year

Radiation

Radiation Exposure

Shuman, W,Radiology 248;2:431-37

RWC Case #4

76 year old male with known CAD with a history of NSTEMI in July 2009 -> stent placement to the LAD and LCx who reports:

3 months of non-exertional L shoulder and upper arm discomfort

What is his pre-test probability of obstructive CAD?

Bayes’ Theorem

RWC Case #4

Referred for treadmill EKG test

Bruce Protocol

6 minutes

L arm pain and diaphoresis

130/90 mmHg (rest) 96/70 mmHg at peak exercise

1 mm ST segment elevation in the inferior leads

Invasive Coronary Angiography

Safety of Stress Echo

Exercise > dipyridamole > DSE

1/6,574 1/557

N=85,997

1/1,294

RWC Case #5

92 year old active female with a h/o CAD, s/p CABG x 3 in 1980 who lives alone presented to the ED with 12 hours of chest pressure. No improvement with sl ntg or asa.

Ruled out for MI in ED, EKG normal; cxr normal

What is her pre-test probability of obstructive CAD?

Bayes’ Theorem

90-99

RWC Case #5

Same-day treadmill test

9:30 seconds on modified Bruce Protocol (4.6 METs)

128 bpm (100% of MPHR)

Normal blood pressure response

Pt did not report cp or dyspnea with exercise

Non-specific st-t changes that did not meet criteria for ischemia

RWC Case #5

She presented to the RWC ED about two weeks later with recurrent chest pain and nausea

EKG showed changes consistent with acute posterior ST segment elevation MI

Heart Alert activated; patient taken urgently to RWC cath lab

Invasive Coronary Angiography

Invasive Coronary Angiography

Case Discussion

Why was this patient’s treadmill test negative?

Non-obstructive disease (true negative)

Obstructive disease (false negative)

Stress Testing in CABG patients

Exercise echo and coronary angiography performed in 182 CABG patients

JACC 1995;25:1019-23

Stress Testing in CABG Patients

“The exercise ECG has a number of limitations after

coronary bypass surgery. Resting ECG abnormalities are

frequent, and if an imaging test is not incorporated in the

study, more reliance must be placed on symptom status,

hemodynamic response, and exercise capacity. Because of

these considerations, together with the need to document

the site of ischemia, stress imaging tests are more favored

in this group, although there are insufficient data to justify

recommending a particular frequency of testing.”

ACC/AHA 2002 Guideline Update for Exercise Testing

Plaque Rupture

Circulation. 1995 Aug 1;92(3):657-71.

86%

Plaque Rupture

Subclinical Coronary Atherosclerosis

How do we identify patients who may have subclinical (non-obstructive) coronary artery disease?

Framingham Risk Score (FRS)

Age

HTN

Sex

Dyslipidemia

Smoker

Diabetic

FRS calculates a 10 year risk of death of MI

Low <10%

Intermediate 10-20%

High >20%

Wilson PW. Prediction of coronary heart disease using risk factor categories. Circulation. 1998; 97 : 1837-47

Coronary Calcium Score

Limited CT scan to assess calcification of coronary arteries

Coronary calcification is marker of atherosclerosis

1-2 mSv (plain film lumbar spine)

Coronary Calcium Score

High sensitivity for CAD but low specificity for obstructive CAD

Incremental predictive value over Framingham risk score

Indication:

Asymptomatic

Intermediate FRS (10-20% 10 year risk)

60 year old non-smoking male with:

Hypertension

Total cholesterol 190

HDL 40 LDL 125

FRS: 11% (10 years) or 1.1 % in 1 year

Coronary Calcium Score

ACCF/AHA 2007 Clinical Expert Consensus on Coronary Artery Calcium Scoring

Conclusions

Functional versus anatomic

Obstructive CAD versus the presence of CAD

Bayes’ theorem and intermediate risk

Treadmill test is safe and effective and should be first-line

in appropriate patients

Conclusions

CT Coronary Angiography

Radiation

CABG patients consider stress testing with imaging

Framingham Score

Intermediate risk population consider coronary calcium score

Bonus Clinical Case

51 year old asymptomatic obese female with DM II referred for persantine SPECT (stress test) for “pre-op evaluation for bariatric surgery.”

Is pre-operative cardiac stress test indicated?

Results

A mildly abnormal study with:

1) small reversible area (ischemia) over the anteroseptal wall

2) a fixed area (infarct) over the inferolateral wall

3) normal left ventricular (LV) systolic function

Referred for cardiac CT because of abnormal SPECT

1) Normal coronary arteries