Value of an Exercise Workload >=10 Metabolic Equivalents for Predicting Inducible Myocardial Ischemia.
Circ Cardiovasc Imaging. 2013 Sep 13;
Authors: Peteiro J, Bouzas-Mosquera A, Broullón F, Martinez D, Yañez J, Castro-Beiras A
BACKGROUND: -We sought to identify extensive ischemia on exercise echocardiography (ExE) relative to workload in patients without known coronary artery disease (CAD), and to investigate whether ExE is useful in predicting outcomes in those with high exercise capacity (≥10 metabolic equivalents [METs]) plus a maximal test (≥85% of their maximal age-predicted heart rate [MAPHR]).
METHODS AND RESULTS: -The analysis was performed on 4,269 patients who underwent ExE, of whom 3,995 achieved ≥85% of their MAPHR. These patients were divided according to the reached workload (<7, 7 to 9, or ≥10 METs) and compared for ExE results. Outcomes in the group achieving ≥10 METs plus ≥85% of their MAPHR (n=2,221) was specifically assessed. Ischemia was defined as new/worsening wall motion abnormalities with exercise. ExE results were different between groups as the METs were lower. Still, among patients achieving ≥10 METs plus ≥85% of their MAPHR, 9.3% had extensive ischemia and 6% multiterritory disease. During follow-up in this subgroup, 108 patients died and 42 had a MACE. Annualized mortality and MACE rates were 0.84% and 0.32% in patients without ischemia vs. 2.26% and 0.84% in those with ischemia (p <0.001, and p=0.002). Ischemia was an independent predictor of mortality (hazard ratio [HR] 1.88, 95% confidence interval [CI] 1.23-2.89, p=0.004) and MACE (HR 2.39, 95% CI 1.22-4.71, p=0.01).
CONCLUSIONS: -Patients without known CAD achieving ≥10 METs plus ≥85% of their MAPHR may still have ischemia. However, the low event rates even in those with ischemia limit the usefulness of imaging for assessing outcomes in this group.
PMID: 24036386 [PubMed - as supplied by publisher]