Ischemia Risk May Be Linked to Exercise Capacity
Risk low if patients at risk for coronary artery disease are able to reach a high exercise workload
TUESDAY, July 28 (HealthDay News) -- Patients at intermediate to high risk of coronary artery disease are at low risk of developing ischemia if they are able to reach a high exercise workload during an exercise stress test, according to a study in the August 4 Journal of the American College of Cardiology.
Jamieson M. Bourque, M.D., and colleagues from the University of Virginia Health System in Charlottesville performed single-photon emission computed tomography (SPECT) myocardial perfusion imaging, at rest and during exercise stress, on 1,056 patients with intermediate to high risk of coronary artery disease. Of these, 974 reached 85 percent or more of their maximum age-predicted heart rate.
Among the 974 patients, the researchers found that the prevalence of significant ischemia was significantly lower in the 473 patients who achieved 10 metabolic equivalents (METs) or more compared with the 267 patients who achieved less than seven METs. Also, the 430 patients who achieved 10 METs or more without exercise ST-segment depression had no incidence of 10 percent or more left ventricular ischemia, whereas the 70 patients who achieved less than 10 METs with ST-segment depression had a 19.4 percent incidence.
"In this referral cohort of patients with an intermediate-to-high clinical risk of coronary artery disease, achieving 10 METs or more with no ischemic ST-segment depression was associated with a 0 percent prevalence of significant ischemia," Bourque and colleagues conclude. "Elimination of MPI in such patients, who represented 31 percent (430 of 1,396) of all patients undergoing exercise SPECT in this laboratory, could provide substantial cost-savings."