Attenuation of exercise-induced R wave increase after diltiazem in effort angina pectoris.

Body surface mapping was used to study the effects of diltiazem on exercise-induced QRS amplitude changes in 7 patients with stable effort angina pectoris. Body surface areas showing R or S amplitude changes (greater than 0.2 mV) after treadmill exercise were calculated. After the administration of 90 mg of diltiazem, the R increased area was significantly smaller than that without diltiazem (p less than 0.02), although the same workload was performed. It was suggested that diltiazem diminished the exercise-induced myocardial ischemia and this improvement of ischemia resulted in the reduction of the R increased area after exercise.