Asymptomatic myocardial ischemia during percutaneous transluminal coronary angioplasty and importance of prior Q-wave infarction and diabetes mellitus.

Eighty-eight patients undergoing percutaneous transluminal coronary angioplasty (PTCA) of 100 stenoses were studied for the presence of factors deemed significant in the etiology of silent myocardial ischemia. Thirty-two patients were asymptomatic during balloon dilations of 36 arteries, and 56 patients had angina during PTCA of 64 arteries. There were no differences in age, sex, prior anginal history, antianginal regimen, extent of coronary artery disease and number or duration of inflations between the 2 study groups. Previous infarction (33 vs 12%, p less than 0.02), Q waves in the target area (31 vs 7%, p less than 0.005) and diabetes mellitus (36 vs 17%, p less than 0.05) were present more often in the asymptomatic group. Sixty-four% of all asymptomatic patients had either diabetes or previous infarction in the target territory. Collateral circulation was more frequent in asymptomatic patients, probably reflecting the ability of collateral arteries to ameliorate ischemia. During 2-vessel PTCA, patients without angina during dilation of only 1 of the 2 treated arteries (discordant responders) had previous infarction in that artery's territory (5 of 5, 100%), whereas patients without previous infarction were either symptomatic or asymptomatic (concordant responders) during PTCA of both arteries. This study shows that asymptomatic ischemia occurs frequently during PTCA in patients with symptomatic coronary disease. Prior Q-wave infarction and diabetes mellitus are important, independent factors associated with painless ischemia. It is suggested that infarction produces a localized dysfunction of afferent cardiac pain fibers, whereas diabetes can cause a global cardiac sensory neuropathy.