Myocardial stress perfusion scintigraphy for outcome prediction in patients with severe left ventricular systolic dysfunction

Coronary angiography has been recommended in all patients with suspected chronic coronary syndrome and left ventricular ejection fraction (LVEF) $\le$35%. The role of ischemia testing, for example, through stress-rest myocardial perfusion scintigraphy (MPS), for risk prediction is not well established. We evaluated 1576 consecutive patients referred to MPS and stratified into 3 LV ejection fraction (LVEF) categories: $\le$35%, 36-49%, and $\ge$50%. Patients with LVEF $\le$35% were oldest, most often men, and with the highest likelihood of prior early (elective or urgent) coronary revascularization. They had also the highest values or summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS), as well as the highest frequency of significant coronary artery disease, and a greater number of diseased vessels. Follow-up: In this subgroup, 32 cardiovascular death or non-fatal myocardial infarction (MI) (21%), 35 all-cause deaths (22%), and 37 cardiovascular deaths, non-fatal MI, or late revascularizations (27%) were recorded with the shortest survival among all LVEF classes. SRS, SSS, and SDS had very low area under the curve values for the prediction of the 3 endpoints, with very high cut-offs, respectively. SRS and SSS cut-offs predicted a worse outcome in Cox regression models including the number of diseased vessels and early revascularization. In patients with LVEF $\le$35%, SRS and SSS are less predictive of outcome than in patients with better preserved systolic dysfunction, but their cut-offs retain independent prognostic significance from the number of vessels with significant stenoses and from early revascularization.