Repolarization Changes Induced by Mental Stress in Normal Subjects and Patients with Coronary Artery Disease: Effect of Nitroglycerine

Abstract

Mental stress can significantly affect ventricular repolarization, which could potentially trigger arrhythmias. We compared the effect of mental stress on repolarization indexed by the amplitude and area of the T wave in patients with coronary artery disease (CAD) and healthy subjects. Fourteen healthy controls (11 M, mean age 42 years) and 14 patients with stable CAD (12 M, mean age 64) underwent a mental stress protocol consisting of mental arithmetic followed by a speech (5 minutes each), which was performed on two occasions following either nitroglycerine (NTG) or placebo. Multiple 12-lead electrocardiograms were acquired and repolarization was analyzed using automatically measured T wave amplitude (T(amp)) and area (T(area)). When preceded by placebo the overall effect of mental stress, whether induced by arithmetic or speech, was significantly different in CAD patients compared with controls, with a decrease in T(amp) and T(area) in controls and an increase in patients; e.g., change in T(amp) during arithmetic -20 +/- 3 microV in controls versus 4 +/- 2 microV in patients, p < .001, and during speech -9 +/- 3 microV in controls versus 7 +/- 1 microV in patients, p < .001. Following NTG, the effect of stress on repolarization was similar in the 2 groups, with a reversed effect, i.e., decrease instead of increase in T(amp) and T(area) in CAD patients. The effect of mental stress on ventricular repolarization is significantly different in CAD patients compared with healthy controls. These differences are considerably reduced by NTG.