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.

BACKGROUND: 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.

METHODS AND RESULTS: 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).

CONCLUSIONS: 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.