Single-Photon Emission Computed Tomography After Nitrate Administration Predicts Cardiac Events in Patients With Previous Myocardial Infarction and Left Ventricular Dysfunction

Abstract

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 ≥2 dysfunctional segments with preserved tracer uptake (≥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.