Effects of coronary artery narrowing, collaterals, and left ventricular function on the pattern of myocardial perfusion

Abstract

We evaluated effects of the degree of diameter narrowing of the coronary arteries (50–69%, 70–89%, ≥90%); extent of coronary disease [one‐vessel disease (1VD), two‐vessel (2VD), three‐vessel (3VD)]; collaterals; and left ventricular function on the pattern of exercise thallium‐201 perfusion in 121 patients; 30 patients with normal coronary angiograms, 37 with 1VD, 24 with 2VD, and 30 with 3VD. Fifteen patients had Q waves on ECG, 29 patients had akinetic segments on the left ventriculogram, and 46 patients had collaterals. The results suggest the following: 1) Patients with 59–69% narrowing of one vessel have normal exercise perfusion. 2) All patients with 1VD have abnormal exercise perfusion if the degree of narrowing is ≥90%, unless the right coronary artery (RCA) is the vessel involved. 3) Patients with 2VD and 3VD generally have abnormal exercise perfusion unless all the narrowings are <90%, or the RCA is the only vessel with ≥90% narrowing, or the stress is submaximal. 4) Collaterals do not protect against development of abnormal exercise perfusion; they feed the most severely narrowed vessel, and perfusion abnormalities are ordinarily seen in the distribution of such severely narrowed vessels. 5) Neither the presence of Q waves on the ECG nor an akinetic segment on the left ventriculogram correlates with defects in the redistribution images; residual defects may be seen in the delayed images despite the absence of prior myocardial infarction, and normal images may be seen despite the presence of akinetic segments in the left ventriculogram.