The practice patterns and outcomes of protected left main (PLM) and unprotected left main (ULM) percutaneous coronary intervention (PCI) are not well defined in contemporary US clinical practice. Data were collected from all Veteran Affairs catheterization laboratories participating in the Clinical Assessment Reporting and Tracking Program between 2009 and 2019. The analysis included 4,351 patients who underwent left main PCI, of whom 1,306 pairs of PLM and ULM PCI were included in a propensity-matched cohort. Selected temporal trends were also assessed. The primary outcome was major adverse cardiovascular event (MACE) outcomes at 1 year, which was defined as a composite of all-cause mortality, rehospitalization for myocardial infarction (MI), rehospitalization for stroke, or urgent revascularization. Patients who underwent ULM PCI compared with patients who underwent PLM PCI were older (age 71.5 vs 69.2 years, p <0.001), more clinically complex, and more likely to present with acute coronary syndrome. In the propensity-matched cohort, radial access was used more often for ULM PCI (21% [273] vs 14% [185], p <0.001) and ULM PCI was more likely to involve the left main bifurcation (22% vs 14%, p = 0.003) and require mechanical circulatory support (10% [134] vs 1% [17], p <0.001). The 1-year MACEs occurred more frequently with ULM PCI than PLM PCI (22% [289] vs 16% [215], p ≤0.001) and all-cause mortality was also higher (16% [213] vs 10% [125], p ≤0.001). In the matched cohort, there was a low incidence of rehospitalization for MI (4% [48] ULM vs 4% [48] PLM, p = 1.000) or revascularization (7% [94] ULM vs 6% [84] PLM, p = 0.485). In this real-world experience, patients who underwent PLM PCI had better 1-year outcomes than those who underwent ULM PCI; however, in both groups, there was a high rate of mortality and MACEs at 1 year despite a relatively low rate of MI or revascularization.

Figure illustrating the study design, follow-up period, and end points. The cumulative incidence curve demonstrates gradual diversion of the curves suggesting that factors after the initial intervention were associated with long-term adverse events. Unprotected left main PCI was associated with a 22% incidence of major cardiovascular adverse events at 1 year compared with 16% for protected left main PCI.