Prognostic implications of symptomatic versus asymptomatic (silent) myocardial ischemia induced by exercise in mildly symptomatic and in asymptomatic patients with angiographically documented coronary artery disease

Patients with coronary artery disease (CAD) may undergo periods of reversible myocardial ischemia without experiencing angina. To study the prognostic implications of "silent" myocardial ischemia induced by exercise, exercise electrocardiography and radionuclide angiography were performed in 131 consecutive patients with CAD, preserved left ventricular. (LV) function at rest and mild or no symptoms during medical therapy. All patients who died during medical therapy were in the subgroup of patients with 3-vessel CAD in whom exercise-induced ischemia developed, which was characterized by both a decrease in LV ejection fraction and ST-segment depression. Patients in whom angina pectoris developed during exercise (54% of all patients) had a greater prevalence of this combined ischemia response to exercise than patients without angina (61% vs 27%, p <0.001) and also a greater prevalence of left main or 3-vessel CAD (59% vs 25%, p <0.001). However, when inducible ischemia was demonstrated, risk stratification and prognosis were the same whether the ischemic episode was symptomatic or silent. Among patients having both a reduction in ejection fraction and a positive ST-segment response, the likelihood of significant left main narrowing (13% vs 26%), 3-vessel CAD (56% vs 51% ) and death during subsequent medical therapy (16% vs 9%) was similar in patients with silent compared to those with symptomatic ischemia. These data indicate that patients in whom angina develops during exercise have a greater prevalence of high-risk coronary anatomy and of inducible ischemia than patients without angina. However, once inducible ischemia is documented, the symptomatic response to exercise appears irrelevant for prognostic or risk stratification considerations.