Exercise-induced QRS duration changes in patients with coronary artery disease-appearing "walkthrough" angina.

Two patients with coronary artery disease appearing as "walkthrough" angina underwent a treadmill exercise test. During the exercise, the patients appeared to have anginal pain associated with ST-segment depression and increased QRS duration. As the patients continued walking, anginal pain disappeared and a concomitant lessening in ST-segment depression and QRS prolongation was observed. Thus, the fact that the onset of angina was associated with ST-segment depression and prolonged QRS duration, while the disappearance of angina was associated with a decrease in ST-segment depression and QRS prolongation, is indicative of the effect of exercise-induced myocardial ischemia on QRS duration.