Habib Abbas Dakik

Long-Term Prognostic Value of Exercise Echocardiography Compared With Exercise 201Tl, ECG, and Clinical Variables in Patients Evaluated for Coronary Artery Disease

BACKGROUND The accuracy of exercise echocardiography and 201Tl single photon emission computed tomography (SPECT) is similar in the diagnosis of coronary artery disease (CAD). However, comparative data on long-term prognosis are lacking. METHODS AND RESULTS Clinical variables and exercise, echocardiographic, and 201Tl tomographic parameters were studied in 248 patients (age, 56+/-12 years [mean+/-SD]; 189 men) who underwent simultaneous treadmill exercise 201Tl SPECT and echocardiography. Follow-up was obtained in 225 patients (91%) at a mean of 3.7+/-2.0 years. A total of 64 cardiac events occurred. With the use of stepwise logistic regression, 4 models simulating clinical stress testing scenarios were evaluated in the prediction of all cardiac events, ischemic events, and/or cardiac death. The best clinical models were exercise echocardiography with exercise ECG and exercise 201Tl SPECT with exercise ECG. Both models were comparable in the prediction of cardiac events. For the exercise echocardiography model, exercise wall motion score index and induction of ischemia were the strongest predictors of events with ORs of 2.63 per unit increment (95% CI, 1. 34 to 5.17; P=0.005) and 4.1 (95% CI, 1.32 to 12.79; P=0.015), respectively. For the model with exercise 201Tl SPECT, the strongest predictor was ischemic perfusion defect (OR, 4.93; 95% CI, 1.72 to 14.08; P=0.003). The absence of ST changes during exercise decreased the risk of events. For the prediction of ischemic events and/or cardiac death, echocardiographic and 201Tl parameters were the only predictive variables. CONCLUSIONS In patients evaluated for CAD, exercise echocardiography and 201Tl combined with ECG variables provide comparable prognostic information and can be used interchangeably for risk stratification.

Intensive Medical Therapy Versus Coronary Angioplasty for Suppression of Myocardial Ischemia in Survivors of Acute Myocardial Infarction A Prospective, Randomized Pilot Study

BACKGROUND Patients who have inducible ischemia after acute myocardial infarction (AMI) generally undergo coronary angiography with the intent to revascularize. Whether this approach is superior to intensive treatment with anti-ischemic medications is unknown. METHODS AND RESULTS We performed a prospective, randomized pilot study comparing intensive medical therapy with coronary angioplasty (PTCA) for suppression of myocardial ischemia in 44 stable survivors of AMI. Myocardial ischemia was quantified with adenosine 201Tl tomography (SPECT) performed 4.5+/-2.9 days after AMI. All patients at baseline had a large total (>/=20%) and ischemic (>/=10%) left ventricular perfusion defect size (PDS). SPECT was repeated at 43+/-26 days after therapy was optimized. The total stress-induced PDS was comparably reduced with medical therapy (from 38+/-13% to 26+/-16%; P<0.0001) and PTCA (from 35+/-12% to 20+/-16%; P<0.0001). The reduction in ischemic PDS was also similar (P=NS) in both groups. Cardiac events occurred in 7 of 44 patients over 12+/-5 months. Patients who remained clinically stable had a greater reduction in ischemic PDS (-13+/-9%) than those who had a recurrent cardiac event (-5+/-7%; P<0.02). Event-free survival was superior in the 24 patients who had a significant (>/=9%) reduction in PDS (96%) compared with those who did not (65%; P=0.009). CONCLUSIONS In this small pilot study, intensive medical therapy and PTCA were comparable at suppressing ischemia in stable patients after AMI. Sequential imaging with adenosine SPECT can track changes in PDS after anti-ischemic therapies and thereby predict subsequent outcome. Corroboration of these preliminary findings in a larger cardiac-event trial is warranted.

Assessment of Myocardial Viability With 99mTc-Sestamibi Tomography Before Coronary Bypass Graft Surgery Correlation With Histopathology and Postoperative Improvement in Cardiac Function

BACKGROUND Assessment of myocardial viability by 99mTc-sestamibi remains controversial. Accordingly, we investigated the use of sestamibi as a marker of myocardial viability, defined by histopathology, and for predicting improvement of myocardial function after coronary artery bypass graft surgery (CABG). METHODS AND RESULTS 99mTc-sestamibi perfusion tomography and radionuclide angiography were performed within 2 days before CABG in 21 patients with > or = 75% stenosis of the left anterior descending coronary artery and resting anterior wall dyssynergy. During CABG, transmural myocardial biopsies were obtained from the dyssynergic anterior wall and from normal myocardial segments to determine the extent of viable myocardium by histopathology. Improvement of regional left ventricular function was evaluated by radionuclide angiography at 6 to 8 weeks after CABG. There was a good correlation (r=.85, P<.001) between the quantified sestamibi activity and the extent of viable myocardium determined morphometrically. Among 21 biopsied dyssynergic myocardial segments, 11 improved their function after CABG and 10 failed to improve. Biopsied segments with improved postoperative function had significantly higher sestamibi activity (81+/-5% versus 49+/-16%, P<.0001) and significantly lower extent of interstitial fibrosis (7+/-4% versus 31+/-21%, P=.0002) than segments that failed to improve. A 55% threshold of 99mTc-sestamibi activity had positive and negative predictive values of 79% and 100%, respectively, for recovery of function after CABG in the biopsied segments. CONCLUSIONS Myocardial 99mTc-sestamibi activity correlates well with the extent of viable myocardium and predicts improvement in regional function after CABG. This lends support to the use of sestamibi as a myocardial viability agent.

Prognostic Value of Exercise 201Tl Tomography in Patients Treated With Thrombolytic Therapy During Acute Myocardial Infarction

BACKGROUND Although myocardial perfusion scintigraphy is of proven value in the risk stratification of patients with a recent myocardial infarction who receive conventional therapy, its value in patients undergoing thrombolytic therapy remains controversial. METHODS AND RESULTS Seventy-one patients who received thrombolytic therapy for acute myocardial infarction had exercise 201Tl tomography and coronary angiography before hospital discharge. Eleven (15%) of 71 patients had ischemic ST-segment depression during exercise, whereas 27 patients (38%) had scintigraphic ischemia. Twenty-five (37%) of 68 patients had a cardiac event consisting of either death (n = 2), recurrent myocardial infarction (n = 5), congestive heart failure (n = 7), or unstable angina (n = 11) during a follow-up of 26 +/- 18 months. Univariate predictors of cardiac events were as follows: Killip class (P = .04); left ventricular ejection fraction (P < .0005); total (P = .002) and ischemic (P < .0005) perfusion defect size; percent thallium lung uptake (P = .001); presence of infarct-zone redistribution (P = .02); and multivessel coronary artery disease (P = .01). By multivariate analysis, the significant joint predictors of risk were ejection fraction (P < .0005) and ischemic perfusion defect size (P = .005). The combination of ejection fraction and thallium tomography added significant incremental prognostic information to the clinical data, whereas angiography did not further improve a model that included clinical, ejection fraction, and tomographic variables. CONCLUSIONS Quantitative exercise 201Tl tomography provides important incremental, long-term prognostic information in patients receiving thrombolytic therapy for acute myocardial infarction.

Tolerance, hemodynamic changes, and safety of dobutamine stress perfusion imaging

BackgroundDobutamine myocardial perfusion perfusion imaging is being used increasingly for assessment of coronary artery disease. Heretofore, there have been no large series documenting its tolerance and safety. The aims of this study were to assess the tolerance, hemodynamic changes, and safety of dobutamine stress in conjunction with myocardial perfusion imaging.Methods and ResultsThe tolerance, hemodynamic changes, and safety of dobutamine myocardial perfusion imaging were investigated in a consecutive series of 1012 patients. Dobutamine was infused at incremental doses of 10, 20, 30, and 40 μg/kg/min at 3-minute intervals. Perfusion tomography was performed according to standard protocols with either 201Tl or 99mTc-labeled sestamibi. Seven hundred twenty-nine patients (72%) reached a maximal dobutamine dose of 40 μg/kg/min. Dobutamine significantly increased heart rate (76±14 beats/min to 127±20 beats/min; p<0.001) and systolic blood pressure (141±20 mm Hg to 168±36 mm Hg; p<0.001) from baseline to peak infusion rate. The most common side effects were chest pain (31%), headache (14%), dyspnea (12%), palpitations (10%), and flushing (10%). There was no death, myocardial infarction, pulmonary edema, ventricular fibrillation, sustained ventricular tachycardia, or cerebral vascular accident. Nonsustained ventricular tachycardia occurred in 43 patients (4.2%) but did not cause any hemodynamic instability.ConclusionWhen done with the necessary caution, dobutamine myocardial perfusion imaging is a safe diagnostic test, although side effects are common.

Association of angiotensin I-converting enzyme gene polymorphism with myocardial ischemia and patency of infarct-related artery in patients with acute myocardial infarction

OBJECTIVES We determined the influence of angiotensin I-converting enzyme (ACE) insertion (I)/deletion (D) polymorphism on the extent of myocardial ischemia in patients with acute myocardial infarction. BACKGROUND The I/D polymorphism, which in part controls plasma and tissue expression of ACE, has been implicated in predisposition to myocardial infarction and ventricular remodeling. METHODS I/D genotyping, predischarge adenosine-thallium-201 perfusion tomography and radionuclide angiography were performed in 113 patients (72 men, 41 women) with a diagnosis of acute myocardial infarction. A subgroup of 96 patients also underwent coronary angiography. RESULTS Genotypes DD, ID and II were present in 27, 56 and 30 patients, respectively. There was no significant difference in the baseline characteristics of patients, total creatine kinase, peak MB fraction, Killip class, mean ejection fraction or the number of diseased vessels in patients with the DD, ID or II genotype. However, the size of the total and the reversible perfusion defects was greater in those with DD than in those with ID or II genotype (total defect size [mean +/- SD] 33.7 +/- 22.5%, 29.5 +/- 19.2% and 22.2 +/- 16.0%, respectively [p = 0.022]; reversible defect size 18.0 +/- 16.0%, 12.1 +/- 11.6% and 8.2 +/- 7.8%, respectively [p = 0.006]). Occlusion of the infarct-related artery was also more common in patients with DD genotype (odds ratio 3.9, 95% confidence interval 1.4 to 11.0). Multivariate analysis showed that the I/D genotype was an independent predictor of perfusion defect size and patency of the infarct-related artery (p = 0.001). CONCLUSIONS DD genotype was associated with a larger ischemic defect and occlusion of the infarct-related artery. Patients with DD genotype, having a larger ischemic defect, are expected to be at a greater risk for subsequent cardiovascular events.

Clinical and Angiographic Significance of a Normal Thallium-201 Tomographic Study in Patients With a Strongly Positive Exercise Electrocardiogram

Among 23,059 patients who underwent exercise myocardial tomography between 1985 and 1994 at our institution, there were 817 (3.5%) with a strongly positive exercise electrocardiogram and normal myocardial tomograms. Among these, 52 patients had no conditions known to be associated with a false-positive exercise electrocardiogram and no previous coronary revascularization, and underwent coronary angiography. Of the 32 patients with significant coronary stenoses, 50% had 1-vessel disease and only 22% had 3-vessel disease (p < 0.05). Among 55 stenosed arteries, 56% were of moderate severity (50 to 74%), whereas only 9% had subtotal or total occlusion (95 to 100%) (p < 0.001). There was a significant gender difference in the prevalence of significant coronary stenoses (80% in male vs 24% in female patients, p < 0.0001). A strongly positive exercise electrocardiogram coupled with normal exercise myocardial tomograms is a rare clinical finding. In women, this finding is usually associated with normal coronary arteries, whereas in men it often denotes coronary artery disease, usually of mild to moderate degree.

Fistula Between Left Main, Left Anterior Descending, and Pulmonary Arteries

A 61-year-old man presented with a 2-month history of angina occurring at rest and on exertion. Coronary angiography showed a coronary fistula extending from the left main bifurcation to the distal left anterior descending artery (Fig 1⇓; small arrows). A …