Successful coronary revascularization improves prognosis in patients with previous myocardial infarction and evidence of viable myocardium at thallium-201 imaging

Abstract.

The role of coronary revascularization of dysfunctional myocardium with preserved thallium-201 uptake in determining the prognosis in patients after myocardial infarction remains to be defined. This study was designed to evaluate the effects of successful revascularization on survival and left ventricular (LV) function in patients with previous myocardial infarction and evidence of dysfunctional but still viable myocardium at rest-redistribution ²⁰¹Tl imaging. Seventy-six consecutive patients with LV dysfunction related to previous myocardial infarction and evidence of viable myocardium at rest-redistribution ²⁰¹Tl tomography were followed for 17±8 months. LV ejection fraction (EF) was assessed by radionuclide angiography at baseline and after 13±2 months. Thirty-nine patients were revascularized (group A) and 37 treated medically (group B). During the follow-up there were nine cardiac deaths. Survival rate was 97% in group A and 66% in group B (P<0.01). By Cox multivariate analysis, the extent of viable myocardium was the best predictor of cardiac death (χ²=8.67, P<0.01) and provided additional information to clinical and functional data (P<0.01). The inclusion of revascularization as a variable improved the global χ² of the model from 14.1 to 21.9 (P<0.01). At follow-up, EF had improved by ≥5% in 16 patients. By multivariate logistic analysis, the extent of viable myocardium was the best predictor of EF improvement (χ²=15.49, P<0.001) and provided additional information to clinical and functional data (P<0.01). The inclusion of revascularization as a variable improved the global χ² of the model from 16.8 to 22.5 (P<0.01). These results demonstrate that the total extent of dysfunctional myocardium with preserved ²⁰¹Tl uptake is the strongest predictor of cardiac death in patients after myocardial infarction. Successful revascularization of dysfunctional but viable myocardium improves survival and LVEF in such patients.