Clinical features of left main equivalent coronary disease

Abstract

The clinical presentation and hemodynamic, ventriculographic and coronary arterial findings of 70 patients with left main equivalent coronary artery disease (70 percent or greater reduction in luminal diameter of the left anterior descending and left circumflex vessels prior to any major branches) were compared with those of 75 patients with 60 percent or greater reduction in luminal diameter of the left main coronary artery. The group with left main equivalent disease did not differ significantly from the group with left main stenosis in any clinical descriptors including New York Heart Association functional class, age, sex distribution, type of presenting symptom or history of congestive heart failure or myocardial infarction. Similarly, the two groups did not differ in ejection fraction, cardiac index, left ventricular end-diastolic pressure, left ventricular end-diastolic volume index, extent of left ventricular contraction abnormality or prevalence of associated significant right coronary arterial obstruction. Of the 70 patients with left main equivalent disease, 31 were deemed to be in operable condition but did not undergo coronary bypass surgery for 1 or more months (mean 4.2 months, range 1 to 12). With the exception of four patients who underwent early operation because of unremitting symptoms, the groups undergoing early and delayed operation did not differ in symptomatic state. In the interim between cardiac catheterization and delayed operation, no patient died and one patient (3 percent) had an acute myocardial infarction. These low morbidity and mortality rates differ strikingly from those of patients with left main stenosis reported in the randomized Veterans Administration study, although the patients in the two studies manifested comparable severity of symptoms, extent of left ventricular contraction abnormality and associated right coronary disease. The results suggest that left main equivalent disease, as defined by obstruction of the left anterior descending and circumflex coronary arteries, does not carry the same short-term prognosis as left main coronary artery disease, but probably behaves more like ordinary two or, if the right coronary artery is also obstructed, three vessel coronary artery disease. In this sense, the term left main equivalent disease is a misnomer causing an unnecessary sense of urgency and alarm.