Single-photon emission computed tomography after nitrate administration predicts cardiac events in patients with previous myocardial infarction and left ventricular dysfunction

BACKGROUND: We determined the impact of viability assessment by nitrate single-photon emission computed tomography (SPECT) on cardiac events during long-term follow-up in patients with previous myocardial infarction, impaired left ventricular (LV) function, and no evidence of inducible ischemia. METHODS AND RESULTS: Sestamibi SPECT after nitrate was performed in 93 medically treated patients with previous myocardial infarction and LV dysfunction (ejection fraction < 40%). Viability was defined as > or = 2 dysfunctional segments with preserved tracer uptake (> or = 55% of peak activity). Cardiac events were cardiac death, myocardial infarction and late revascularization. Sixty-five (70%) patients had evidence of viability at SPECT, whereas 28 (30%) did not. During 43 +/- 24 months of follow-up, cardiac events occurred in 32 (49%) of the 65 patients with viability and in 5 (18%) of the 28 patients without (P < .001). At Cox analysis, only the extent of viability predicted cardiac events (hazards ratio 1.6, 95% CI 1.3-2.0, global chi-square 14.3, P < .0001). Cumulative probability of event-free survival was 22% in patients with viability and 81% in those without (P < .001). CONCLUSIONS: The presence of viable myocardium at nitrate SPECT imaging predicts major cardiac events at long-term follow-up and the risk increases with the extent of viability.