[Detection of myocardial ischemia by analysis of the shape of exercise-induced ST elevation in infarct-related leads].

ABSTRACT

OBJECTIVES: Possible mechanisms of exercise-induced ST elevation in infarct-related leads include ventricular dyskinesis, and myocardial ischemia in the infarct region. Detection of ischemia in viable myocardium in the infarct region is important to determine the therapeutic strategy. This study evaluated whether the analysis of the shape of exercise-induced ST elevation(convex or concave type) is useful to detect myocardial ischemia in the infarct region. METHODS: Ninety-eight patients (78 males, 20 females, mean age 59 +/- 10 years) with prior Q wave myocardial infarction underwent the treadmill exercise test. Patients were divided into three groups according to the exercise-induced ST changes No ST-E group, 27 patients without ST changes; Concave ST-E group, 52 patients with concave type ST elevation; Convex ST-E group, 19 patients with convex type ST elevation. Coronary arteriography was evaluated in all patients. Dobutamine stress echocardiography was performed in 38 patients, including 28 patients in the Concave ST-E group and 10 patients in the Convex ST-E group. Biphasic or worsening response on dobutamine stress echocardiography was defined as ischemic response. RESULTS: Coronary arteriography revealed significant stenosis of the infarct-related artery in 30% of the No ST-E group, 47% in the Convex ST-E and 86% in the Concave ST-E groups (p < 0.05). Dobutamine stress echocardiography revealed myocardial ischemia in the infarct region in 30% in the Convex ST-E group and 75% in the Concave ST-E group(p < 0.05). CONCLUSIONS: The Concave ST-E group had a higher incidence of stenosis of the infarct-related artery and myocardial ischemia in the infarct region. Analysis of the shape of exercise-induced ST elevation in infarct-related leads is useful for the detection of ischemia of viable myocardium.