Median survival duration was 13.3 years in the surgical group and 6.6 years in the medical group. The survival benefit of CABG over medical therapy appeared to extend to 53 asymptomatic patients with left main CAD in the CASS Registry.962 Other therapies that subsequently have been shown to be associated with im- proved long-term outcome, such as the use of aspirin, statins, and internal mammary artery grafting, were not widely used in that era. RCTs and subgroup analyses that compare PCI with medical therapy in patients with unprotected left main CAD do not exist. 5.7.2. Studies Comparing PCI Versus CABG for Left Main CAD Of all subjects undergoing coronary angiography, approxi- mately 4% are found to have left main CAD,1090 .80% of whom have significant ($70% diameter) stenoses in other epicardial coronary arteries. Published cohort studies have found that major clinical outcomes are similar with PCI or CABG 1 year after revascularization and that mortality rates are similar at 1, 2, and 5 years of follow-up; however, the risk of needing target-vessel revascularization is significantly higher with stenting than with CABG. In the SYNTAX trial, 45% of screened patients with unprotected left main CAD had complex disease that pre- vented randomization; 89% of these underwent CABG.949,950 In addition, 705 of the 1800 patients who were randomized had revascularization for unprotected left main CAD. The majority of patients with left main CAD and a low SYNTAX score had isolated left main CAD or left main CAD plus 1-vessel CAD; the majority of those with an intermediate score had left main CAD plus 2-vessel CAD; and most of those with a high SYNTAX score had left main CAD plus 3-vessel CAD. 