CORONARY COLLATERAL CIRCULATION

The occurrence and influence of coronary collateral circulation and obstruction of the supplying coronary arteries on left ventricular contractility, prevalence of myocardial infarction, and bicycle exercise ergometer test were studied in a random sample of 286 patients with angiographically documented coronary artery disease. Collaterals appeared increasingly in all three main coronary arteries with grade of obstruction. The highest prevalence of collaterals occurred in stenosis of the right coronary artery (60%), followed by the left descending artery (45%); they occurred least in the left circumflex artery (21%) (p < 0.001). The frequency of intra-arterial collateral circulation was 42%, 11%, and 12%, respectively (p < 0.001). With total occlusion of the left anterior descending coronary artery, 22% of the patients had normokinetic anterior and apical left ventricular wall when collaterals were present. More often, the inferior wall showed normal contraction with total occlusion of the right coronary artery and collaterals [52%, p < 0.001 compared with left anterior descending artery (LAD)]. The prevalence of inferior myocardial infarction was 39%, with collateral circulation to the totally occluded right coronary artery. The respective prevalence of anterior infarction and total occlusion in the left coronary artery was 58% (p < 0.02). The presence or absence of collaterals had no obvious influence on ST-segment response during bicycle ergometer test. In triple-vessel disease, peak work capacity was better when collaterals to LAD were not jeopardized (427 kpm) than when jeopardized (321 kpm) (p < 0.02).