SEVERE EXERCISE-INDUCED ISCHEMIA DOES NOT IDENTIFY HIGH-RISK PATIENTSWITH NORMAL LEFT-VENTRICULAR FUNCTION AND ONE-VESSEL OR 2-VESSEL CORONARY-ARTERY DISEASE

Objectives. This study was conducted to determine whether severe exerc ise-induced ischemia identifies high risk patients with a normal left ventricular ejection fraction and one- or two-vessel coronary artery d isease. Background. Severe ischemia during exercise radionuclide angio graphy has been shown to identify high risk patients among certain oth er patient subsets. Methods. Four hundred twenty patients with left ve ntricular ejection fraction greater-than-or-equal-to 50% and one- or t wo-vessel disease underwent exercise radionuclide angiography within 3 months of coronary angiography. Patients were treated initially with revascularization (n = 140) or medical therapy (n = 280) at the discre tion of their physicians. Patients treated with revascularization were more likely to have angina by history, a positive exercise electrocar diogram, a lower exercise ejection fraction, two-vessel disease and pr oximal left anterior descending coronary artery disease. Two hundred s ixty-four of the 280 patients given medical therapy who had complete f ollow-up data formed the study group. Outcome was compared between pat ients with (n = 56) and without (n = 208) severe exercise-induced isch emia, defined by previously published criteria (work load less-than-or -equal-to 600 kg-m/min, ST segment depression -1 mm and decrease in ej ection fraction with exercise). Results. During follow-up, there were 30 initial cardiac events (12 cardiac deaths and 18 nonfatal myocardia l infarctions). There was no difference in the 5-year event-free survi val rate: 91% in patients with and 87% in patients without severe isch emia (p = 0.89). There was no association between event-free survival and severe ischemia (chi2 = 1.41, p = 0.24). The study had approximate ly 80% power at alpha = 0.05 to detect a 25% decrease in event-free su rvival in the group with severe ischemia. In addition, there was no as sociation between severe ischemia and outcome if late revascularizatio n was included as an event or if the total mortality rate (overall sur vival) was analyzed. Conclusions. Severe exercise-induced ischemia fai ls to identify a high risk subgroup among patients with normal left ve ntricular function and one- or two-vessel disease who are treated init ially with medical therapy.