Should coronary arteries with less than 60% diameter stenosis be treated by angioplasty?

We evaluated all patients receiving percutaneous transluminal coronary angioplasty (PTCA) in the past year for mild stenosis (60% or less diameter narrowing, n = 64, group 1) and compared them with a random sample of 330 patients with greater than 60% stenosis (n = 66, group 2) treated during the same year. The degree of coronary stenosis before PTCA was 52 +/- 7% (mean +/- SD) in group 1 and 79 +/- 11% in group 2. The primary success rate was 90% (58 of 64 patients) in group 1 vs 86% (57 of 66 patients) in group 2. The incidence of complications requiring coronary surgery after PTCA failed was similar in both groups (3 of 64 in group 1, 4 of 66 in group 2), but there were four occurrences of myocardial infarction in group 1 and none in group 2 (p less than .05). Recurrence of stenosis was judged on the basis of objective data, 76% of which were angiographic data, in 97% of the patients with primary success. At a mean interval of 5 months with a mean follow-up period of 7 months, 17 of 58 patients (29%) with primary success in group 1 and 24 of 57 patients (42%) in group 2 developed restenosis. In group 1, restenosis was markedly more severe (73 +/- 15%) than initial stenosis (p less than .005), which was not the case in group 2. In conclusion, PTCA in mild stenosis has favorable primary and long-term results, yet carries the risk of myocardial infarction and emergency operation and may, in some cases, even accelerate the disease process.