using workload to predict left main coronary artery stenosis in candidates for coronary angiography

background: coronary angiography, albeit a safe procedure, may cause serious complications especially in patients with left main stenosis (lms). this study was designed to investigate the efficacy of workload achieved by exercise tolerance test (ett) in predicting lms in candidates for coronary angiography. methods: a total of 743 patients with a positive ett who subsequently underwent cardiac catheterization were retrospectively studied. different risk factors were compared among the patients with and without lms . a multivariate forward stepwise logistic regression analysis was used to identify the main predictors of lms. results: among our 743 patients, 72% were male and 41(5.5%) had lms≥50%. patients with lms, by comparison with those without lms, were older and were more likely to be male and had higher percentages of ejection fraction less than 35% (ef≤35%), history of myocardial infarction, and lower metabolic equivalent (mets). after adjusting for important variables, we found that ef≤35%, mets, and the male sex were significant independent predictors of lms (p<0.0001, p=0.024, and p=0.006, respectively). when the patients were divided into two groups in terms of mets≤7 and mets>7, lms was found in 8.3% and 3.6%, respectively (p=0.006). the risk of having lms in the men with mets≤7 was higher than that in those with mets>7 (or=3, p=0.003, 95% ci=1.50-6.00). among the patients with lms, stenosis≥70% was found in 44% in mets≤7 and 18.8% in mets>7.   conclusion: lower mets correlated with an increased likelihood of significant lms in the patients, especially if they were male, who had a positive exercise test and were suspected of coronary artery disease. it is, therefore, advisable that patients with mets≤7 receive due attention during coronary angiography.