Randomized clinical trials demonstrating safety and efficacy of unprotected left main (ULM) PCI may not reflect its use in clinical practice, according to a study published Jan. 2 in JAMA Cardiology. The study is part of ACC's Research to Practice (R2P) initiative, which identifies impactful cardiovascular research and analyzes its implications for contemporary clinical practice using ACC's NCDR clinical registries.

Using ACC's CathPCI Registry, Javier A. Valle, MD, MSCS, FACC, et al., analyzed data from 33,128 patients undergoing ULM PCI and 3,309,034 undergoing all other PCI to define current ULM PCI practice and compare outcomes to those reported in the EXCEL and NOBLE trials. The primary outcome was in-hospital major adverse clinical events, which included death, myocardial infarction (MI), stroke or emergent CABG. Each outcome also was measured individually. The researchers also compared patient and procedural characteristics between ULM PCI and all other PCI.

The results found that patients undergoing ULM PCI had significantly higher rates of major adverse clinical events (9 percent), compared with other PCI (2.6 percent). In addition, ULM PCI was associated with higher rates for each individual outcome, including death (5 percent vs. 0.6 percent), MI (3.9 percent vs. 1.8 percent), stroke (0.5 percent vs. 0.2 percent), and emergent CABG (0.7 percent vs. 0.1 percent). However, composite rates of in-hospital death, MI, stroke or emergent CABG decreased over time (9.3 percent for 2009 – 2011 vs. 7.8 percent for 2015 – 2016).

In addition, the authors found that individual MI rates went down over time, but individual rates of death, stroke and emergent CABG did not change significantly. Operators and institutions performing ULM PCI had higher annual PCI volume, compared with operators and institutions performing all other PCI. Further, ULM PCI was more likely to be performed at institutions in urban areas with private or community designations.

The study's findings suggest "significantly worse outcomes" for ULM PCI in the study cohort vs. in clinical trials, although the researchers suggest that the difference "likely is attributable to patient and procedural factors." They conclude that clinical trials for ULM PCI likely do not reflect clinical practice and moving forward, "suggest an opportunity to refine patient selection and increase operator and institutional experience" to improve outcomes.

The R2P initiative was launched in 2015. Analyses under the R2P initiative are intended to help facilitate conversations between practice and research, and identify unanswered questions in current clinical research and future investigation topics to consider.

Keywords: Hospital Mortality, Myocardial Infarction, Cohort Studies, Registries, Stroke, Percutaneous Coronary Intervention, National Cardiovascular Data Registries

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