Assessment of Rapid Atrial Pacing in the Diagnosis of Coronary Artery Disease

The sensitivity and specificity of ST segment change on ECG for detection of coronary artery disease(CAD) by pacing stress test were assessed. Among 28 cases with chest pain(mean age 52, M/F : 21/7), 10 patients had normal coronary angiographic finding(Group I), and 18 had coronary artery disease(Group II). Pacing stress test showed high specificity(100%), but low sensitivity(61%) for the diagnosis of CAD. Especially in patients with 1 vessel disease, the sensitivity was only 50%, and positive results were not attained unless there was at least 90% or more stenosis in any of the major branches(LAD, RCA or LCX). But in patients with multivessel disease, the sensitivity was much higher(83%). Lateral(V4-6) or inferior leads(2, 3, aVF) showed ischemic ST segment depression most commonly. Therefore one of the inferior lead and V5 may be a minimum requirement for monitoring pacing-induced ST segment changes. Time constant during isovolumic relaxation showed statistically significant prolongation after pacing only in CAD patient group, suggesting pacing-induced impairment of early left ventricular relaxation.