Prevalence of Angiographically Recognizable Atherosclerosis in Non-Dominant Right Coronary Arteries

Among 1,000 consecutive patients referred for coronary arteriography be cause of chest pain, 89 patients were found to have a non-dominant right coro nary artery (NDRCA). These patients were compared to 89 consecutive patients with dominant right coronary artery (DRCA) matched for age, sex, smoking and serum cholesterol. There was a lower incidence of obstructive disease in NDRCA (23 of 89 patients, 26%) than in DRCA (55 of 89 patients, 62%), χ²=23.368, p < 0.001. The incidence of coronary disease was also lower in the NDRCA group, 50 of 89 patients (56%), than in the DRCA group, 68 of 89 patients (76%), χ²=8.146, p<0.01. When only patients with coronary artery disease (CAD) were included in the analysis: 23 of 50 (46%) patients with CAD and NDRCA had obstructive disease in the right coronary artery (RCA) while 55 of 68 (80%) patients with DRCA and CAD had obstructive disease in the RCA, χ²=15.646, p < 0.001. The lower incidence of disease in NDRCA persisted even when only the proximal one-third of the DRCA was considered: 41 of 89 (46%) patients with DRCA had proximal lesions compared to the total length of NDRCA, 23 of 89 patients (26%), χ²=7.940, p<0.01. We conclude that (1) obstructive atherosclerotic lesions are less frequent in NDRCA than in comparable populations; (2) the length (extension) of the artery does not appear to explain this fact, since the lesser degree of disease persists even when only the proximal segment of dominant right coronary artery was considered; (3) an intriguing observation is that the incidence of obstructive atherosclerotic lesions was lower in NDRCA than in a matched DRCA popula tion.