Is 'silent' myocardial ischemia really as severe as symptomatic ischemia? The analytical effect of patient selection biases

Abstract

Background: The clinical significance of exercise-induced chest pain remains controversial, as reflected by sharply discordant clinical results within the medical literature. Thus, we developed a prospective study to compare the functional significance of silent versus symptomatic ischemia and to evaluate whether patient selection biases influence this analysis. Methods and Results: We evaluated 117 patients (mean age, 63±9 years) with ischemic ST-segment depression during treadmill testing. Each patient underwent Tl- 201 myocardial perfusion single-photon emission computed tomography (SPECT) after exercise followed by 24-ambulatory ECG monitoring. Patients were divided into silent versus symptomatic cohorts and were compared for the degree of hemodynamic, exercise and ambulatory ECG, and thallium abnormalities during stress testing. Analyses were repeated as the patient population became increasingly restricted. Compared with the silent patients, patients with chest pain during exercise had a shorter exercise duration (P