Long-term angiographic follow-up of coronary balloon angioplasty in patients with diabetes mellitus: a clue to the explanation of the results of the BARI study. Balloon Angioplasty Revascularization Investigation.

OBJECTIVES: We sought to compare the angiographic outcome of diabetic patients (treated with insulin or oral hypoglycemic agents) after successful coronary angioplasty with that in nondiabetic patients. The analysis included the outcome of the dilated (restenosis) and nondilated narrowings (disease progression).
BACKGROUND: Recent data have confirmed that diabetes mellitus is an important risk factor for long-term adverse events. These adverse events are more common after balloon angioplasty than after bypass surgery (Bypass Angioplasty Revascularization Investigation [BARI]).
METHODS: We examined retrospectively 353 coronary angiograms of 248 patients (55 diabetic, 193 nondiabetic) who were referred for diagnostic angiography >1 month after successful angioplasty (1.4 +/- 0.6 [mean +/- SD] repeat angiograms/patient). Restenosis and disease progression/regression were compared between groups by means of quantitative angiography.
RESULTS: Baseline clinical and angiographic characteristics were similar in both groups. There was a nonsignificant trend for a higher restenosis rate of dilated narrowings in diabetic patients. There were no significant changes between diabetic and nondiabetic patients in the rates of progression and regression of narrowings that were not dilated during the initial angioplasty. The main difference was in the rate of appearance of new narrowings: There was a 22% increase in the number of narrowings on the follow-up angiogram in diabetic patients (38 new, 174 preexisting narrowings) compared with 12% (86 new, 734 preexisting narrowings) in nondiabetic patients (p < 0.004). Diabetes mellitus and the performance of angioplasty in the artery had an additive risk for development of new narrowings, which were identified in 15 (16.9%) of 89 arteries with and 16 (13.2%) of 121 without angioplasty in diabetic patients and in 42 (12.7%) of 331 arteries with and 38 (7.3%) of 518 without angioplasty in nondiabetic patients (p = 0.009).
CONCLUSIONS: The combination of diabetes mellitus and an artery that was instrumented during balloon angioplasty is additive and increases the risk of formation of new narrowing in that artery. This finding may explain the high adverse event rates observed in diabetic patients in the angioplasty arm of the BARI study, most of whom had angioplasty performed in at least two arteries.