Myocardial perfusion imaging in emergency department patients with negative cardiac biomarkers: yield for detecting ischemia, short-term events, and impact of downstream revascularization on mortality.

Abstract

In patients with possible acute coronary syndromes, guidelines recommend routine provocative testing after negative cardiac biomarkers. We hypothesized that myocardial perfusion imaging would be low yield with limited short-term value and that early revascularization would not affect mortality. We identified consecutive patients referred from our emergency department between October 2004 and September 2011 who had myocardial perfusion imaging after negative troponin T tests and nondiagnostic ECGs. We assessed the incidence of abnormal myocardial perfusion imaging, coronary angiography, revascularization, and mortality. In a cohort of 5354 patients (58.7% female, age 59 ± 13, 78.6% thrombolysis in myocardial infarction [TIMI] ≤2), 9% had >5% and 3.6% had >10% ischemic myocardium. Among patients with TIMI scores ≤2, 6.1% had >5% ischemic myocardium compared with 19.6% of patients with TIMI scores ≥3 (P<0.001). At 30 days, 7 patients were deceased, 187 had revascularization, and 6 had revascularization for an acute myocardial infarction. Over 3.4 ± 1.9 years of follow-up, 347 patients died. In propensity-matched groups of patients with ischemia, there was no association between early revascularization and mortality (hazard ratio, 1.00; 95% confidence interval, 0.49-2.07). Routine provocative testing to detect ischemia before emergency department discharge is low yield in patients with negative troponins and TIMI scores ≤2 and modest yield in patients with TIMI scores ≥3. In all patients, 30 days events are rare. Finally, in patients with ischemia, we are unable to demonstrate a mortality benefit with early revascularization.