Silent ischemia during coronary occlusion produced by balloon inflation: relation to regional myocardial dysfunction.

Thirty patients with stable exertional angina undergoing percutaneous transluminal coronary angioplasty of an isolated obstructive lesion of the proximal left anterior descending artery were prospectively evaluated to investigate the relation between angina induced by balloon inflation and the quantity and severity of myocardial ischemia as determined by electrocardiographic (ECG) monitoring and by echocardiographic assessment of regional and global left ventricular wall motion. Anginal pain interviews, continuous two-dimensional echocardiographic recordings and 12 lead ECG recordings at 10 second intervals were obtained for the first two inflation sequences. Seventeen patients had angina with both inflations (symptomatic group), seven patients had no angina or related symptoms during either inflation (asymptomatic group) and six patients had both painful and painless inflations (mixed response group). Comparison of the three groups revealed that they did not differ in mean age, sex distribution, prior history of angina or the incidence of comorbid conditions. Echocardiographic measurements of global and regional left ventricular dysfunction during balloon inflation were comparable in the symptomatic and asymptomatic groups. Similarly, there were no significant differences in the time to onset or magnitude of ST segment changes. The results of the wall motion and ECG studies in the mixed response group paralleled the results in the symptomatic and asymptomatic groups, with no significant differences in any of the variables measured between the painful and painless inflations. These data demonstrate that silent myocardial ischemia occurs in an appreciable proportion of patients during coronary angioplasty and the absence of angina does not imply that a lesser amount of myocardium is jeopardized than with painful inflations.