Failure of diltiazem to prevent restenosis after percutaneous transluminal coronary angioplasty.

This prospective randomized trial was carried out in 92 patients who underwent a successful percutaneous transluminal coronary angioplasty (PTCA) and had no evidence of coronary spasm before PTCA. All patients were premedicated with calcium antagonists and platelet inhibitors and received platelet inhibitors (aspirin and dipyridamole) for 6 months after PTCA. The diltiazem group (46 patients with 50 stenoses successfully dilated) received diltiazem, 90 mg three times a day by mouth for 3 months after PTCA; in the control group (46 patients, 53 stenoses), calcium antagonists were discontinued immediately after PTCA. All patients underwent a control angiogram 5 to 10 months after PTCA unless recurrence of angina dictated its need earlier. Baseline characteristics were similar in both groups, except for the number of diseased vessels greater than or equal to 70%, which was higher in the control group (1.2 +/- 0.55 vs 0.9 +/- 0.39 for the diltiazem group, p less than 0.05). In the diltiazem group, the degree of stenosis increased from 38 +/- 15% immediately after PTCA to 42 +/- 23% at repeat angiography 8.24 +/- 4.79 months after PTCA and there were seven restenoses. In the control group, the degree of stenosis increased from 37 +/- 12% to 44 +/- 23% at repeat angiography 8.26 +/- 4.91 months after PTCA and there were 10 restenoses (NS vs the diltiazem group). In conclusion, in patients without variant angina before PTCA, adjunction of diltiazem to platelet inhibitors does not decrease the incidence of restenosis. These data suggest that coronary spasm is not the major mechanism of restenosis.