QUANTITATIVE RELATION BETWEEN MYOCARDIAL VIABILITY AND IMPROVEMENT INHEART-FAILURE SYMPTOMS AFTER REVASCULARIZATION IN PATIENTS WITH ISCHEMIC CARDIOMYOPATHY

Background Studies of patients with coronary artery disease and left v entricular dysfunction have shown that preoperative quantification of myocardial viability may be clinically useful to identify those patien ts who will benefit most from revascularization both functionally and prognostically. However, the relation between preoperative extent of v iability and change in heart failure symptoms has not been documented carefully. We assessed the relation between the magnitude of improveme nt in heart failure symptoms after coronary artery bypass surgery (CAB G) and the extent of myocardial viability as assessed by use of quanti tative analysis of preoperative positron emission tomography (PET) ima ges. Methods and Results We studied 36 patients with ischemic cardiomy opathy (mean left ventricular ejection fraction, 28+/-6%) undergoing C ABG. Preoperative extent and severity of perfusion abnormalities and m yocardial viability (flow-metabolism mismatch) were assessed by use of quantitative analysis of PET images with N-13 ammonia and fluorine-18 -deoxyglucose. Each patient's functional status was determined before and after CABG by use of a Specific Activity Scale. Mean perfusion def ect size and severity were 63+/-13% and 33+/-12%, respectively. Total extent of a PET mismatch correlated linearly and significantly with pe rcent improvement in functional status after CABG (r=.87, P<.0001). A blood flow-metabolism mismatch greater than or equal to 18% was associ ated with a sensitivity of 76% and a specificity of 78% for predicting a change in functional status after revascularization. Patients with large mismatches (greater than or equal to 18%) achieved a significant ly higher functional status compared with those with minimal or no PET mismatch (<5%) (5.7+/-0.8 versus 4.9+/-0.7 metabolic equivalents, P=. 009). This resulted in an improvement of 107% in patients with large m ismatches compared with only 34% in patients with minimal or no PET mi smatch. Conclusions In patients with ischemic cardiomyopathy, the magn itude of improvement in heart failure symptoms after CABG is related t o the preoperative extent and magnitude of myocardial viability as ass essed by use of PET imaging. Patients with large perfusion-metabolism mismatches exhibit the greatest clinical benefit after CABG.