Myocardial salvage assessed by (99m)Tc-sestamibi scintigraphy is a marker of myocardial tissue reperfusion in patients with acute myocardial infarction. The prognostic value of myocardial salvage index in patients with acute myocardial infarction after reperfusion therapy has not, however, been investigated.
Methods: We analyzed 765 patients with acute myocardial infarction randomized to treatment by coronary stenting (383 patients), primary coronary angioplasty (251 patients), or thrombolysis (131 patients) in the setting of 3 randomized trials. Initial (before reperfusion therapy) and follow-up (7-14 d after reperfusion therapy) scintigraphic examinations were performed to assess the initial perfusion defect, final infarct size, and salvage index. Patients were categorized into 2 groups defined by the median salvage index (0.5): the group with salvage index < 0.5 (374 patients) and the group with salvage index >or= 0.5 (391 patients). The primary endpoint of the study was mortality at 6 mo after the index event.
Results: Six-month mortality was 5.1% (19 deaths) in the group with salvage index < 0.5, compared with 1.0% (4 deaths) in the group with salvage index >or= 0.5 (odds ratio, 5.1; 95% confidence interval, 1.9-13.3; P = 0.001). Salvage index (median [25th, 75th percentiles] was significantly smaller in nonsurvivors than in survivors (0.19 [0.05, 0.37] vs. 0.50 [0.26, 0.80], P = 0.0004). The Cox proportional hazards model showed that myocardial salvage index (P = 0.0007), initial perfusion defect (P = 0.0007), and age (P = 0.04) were independently associated with 6-mo mortality.
Conclusion: Myocardial salvage achieved by reperfusion therapy predicts mortality in patients with acute myocardial infarction. Our findings support the use of salvage index as a surrogate of mortality in clinical trials designed to test the efficacy of reperfusion therapies among patients with acute myocardial infarction.