Catheterization and Cardiovascular Diagnosis 13:317-320 (1987) Total Occlusion of the Left Main Coronary Artery in Chronic Stable Angina Pectoris Krishnankutty Sudhir, zyxwvut MBBS, Abraham K. Abraham, MD, DM(Card), Maman K. Cherian, zy MS, FRACS, Narasimha K. Reddy, MD, DM(Card), and Srikrishna Gupta, MD, DM(Card) We present the clinical and angiographic profile of three patients with class I stable angina pectoris. All had strong coronary risk factors, and stress testing was positive in stage one of the Bruce protocol. Coronary angiography revealed total occlusion of the left main coronary artery (LMCA), and aortocoronary bypass surgery was performed. Thus, total LMCA occlusion may be an unexpected angiographicfinding in patients with class I angina. Key words: coronary disease, collateral circulation INTRODUCTION zyxwvutsrq Total occlusion of the left main coronary artery (LMCA) is an unexpected finding in patients undergoing coronary arteriography zyxwvutsr . The Coronary Artery Surgery Study [1] reported an incidence of 0.06% in patients without prior surgery. In patients with chronic stable angina pectoris, survival in the presence of total obstruc- tion of the LMCA depends on an adequate collateral circulation [2]. Total occlusion of the LMCA has been described in class I11 and IV angina pectoris [3], in unstable angina [4], and in evolving myocardial infarc- tion 151. However, the finding of 100% LMCA occlusion in ambulant subjects, asymptomatic except for class I angina, is a clinical curiosity. This report describes the clinical and angiographic findings in three such patients. CASE REPORTS Case 1 Mr. M. was a 55-year-old noninsulin-dependent dia- betic, presenting with mild stable angina (class I, New York Heart Association). He had no palpitations, dysp- nea, or fatigue. There was no antecedent history of myo- cardial infarction, and he was on conventional therapy for coronary artery disease (CAD) with a beta-blocker and a nitrate. Physical examination revealed mild sys- temic hypertension and a prominent fourth heart sound. The chest X-ray was normal. The resting EKG was normal except for T-wave inversion in inferolateral leads. The treadmill test revealed > 2 mm flat ST depression in stage one of the Bruce protocol, persisting for more than zyxwvu 5 min after cessation of exercise. Left ventricular (LV) angiography revealed well-preserved LV function (Fig. 1) except for mild hypokinesia of the anterolateral and api- cal segments. Coronary arteriography showed 100% oc- @ 1987 Alan R. Liss, Inc. clusion of the LMCA, 1 to 2 mm distal to the ostium, and 90% stenosis of the proximal right coronary artery (RCA). The left anterior descending artery (LADA) and circumflex artery were clearly visualized, filling through collaterals from the RCA (Fig. 2A). The patient under- went aortocoronary bypass grafting to the LADA, obtuse marginal artery (OMA), and distal RCA. Case 2 Mr. R., aged 38 years, was also asymptomatic except for mild stable class I angina, and had no antecedent history of myocardial infarction. There was a strong family history of diabetes, and the patient had type IIB hyperlipoproteinemia. He was receiving a beta-blocker and a nitrate. The physical examination, chest X-ray, resting EKG, treadmill test, and LV angiogram revealed identical findings to those in case 1. The LMCA, on coronary angiography, showed 100% occlusion, the LADA and circumflex artery filling through collaterals from the RCA (Fig. 2B). The patient underwent aorto- coronary bypass grafting to the LADA and OMA. Case 3 Mr. F., aged 49 years, also presented with class I angina. He had suffered two previous infarctions involv- ing the inferior and anterior walls. He had noninsulin- dependent diabetes, and type IIB hyperlipoproteinemia. From the Southern Railway Headquarters Hospital, Perambur, Madras, India. Received September 26, 1986; revision accepted March 18, 1987. Address reprint requests to Dr. K. Sudhir, who is currently at Clinical Research Unit, Baker Medical Research Institute, Commercial Road, Prahran, Victoria 3 181, Australia.