The effects of diltiazem on cardiac function in silent ischemia after myocardial infarction

In a total group of 56 patients with an acute myocardial infarction who were maximally exercised at predischarge, 20 patients (36%) showed greater than or equal to 1 mm asymptomatic ST-T segment depression during exercise. The site of the infarction was anterior in 12 patients and inferior in eight patients. All 20 patients underwent repeated exercise radionuclide angiography 2 days later, 2 hours following oral intake of 120 mg of diltiazem. Double product was not significantly different before and after diltiazem, both at rest and during exercise. Maximal ST-T depression after diltiazem was reduced from 2.3 +/- 0.8 to 0.7 +/- 0.6 mm (p less than 0.01). Left ventricular (LV) ejection fraction at rest before diltiazem was 54.4 +/- 8.7% and after diltiazem was 56.2 +/- 11.3% (p = NS). During exercise, LV ejection fraction improved after diltiazem from 43.2 +/- 12.2% to 49.8 +/- 10.5% (p less than 0.05). Regional wall motion score (1 = normal, 2 = hypokinetic, 3 = akinetic, 4 = dyskinetic) at rest before diltiazem was 9.6 +/- 2.0 and after diltiazem was 9.1 +/- 1.8 (p = NS). During exercise, regional wall motion score improved after diltiazem from 5.8 +/- 1.3 to 4.3 +/- 1.1 (p less than 0.02). We conclude that silent ischemia occurs in a substantial number of patients after myocardial infarction and that diltiazem has acute beneficial effects on asymptomatic ST-T depression and on global and regional LV function in post-infarction patients with silent ischemia.