With evidence indicating that a large area of myocardium is jeopardized by left main coronary artery (LMCA) disease, LMCA disease could be associated with left ventricular (LV) dysfunction, which is subsequently related with increased mortality, explains Duk-Woo Park, MD, PhD. “Although PCI is increasingly performed in patients with LMCA disease following several landmark trials showing at least comparable outcomes between CABG and PCI in LMCA disease, the optimal revascularization strategy for patients with LMCA disease and LV dysfunction is still unclear,” he adds.
CABG Vs PCI
For a study published in the Journal of the American College of Cardiology, Dr. Park and colleagues sought to evaluate the relative treatment effect of revascularization strategy (CABG vs PCI) according to the severity of LV dysfunction in patients with LMCA disease. “The Interventional Research Incorporation Society-Left MAIN Revascularization (IRIS-MAIN) registry is a nonrandomized, multinational, observational registry enrolling ‘all-comers’ with LMCA disease,” notes Dr. Park. “From this registry, 3,488 patients with LMCA disease who underwent CABG or PCI were categorized into normal (LVEF ≥55%, n = 2,641), mild (LVEF ≥45% to <55%, n = 403), moderate (LVEF ≥35% to <45%, n = 260), or severe LV dysfunction (LVEF <35%, n = 184) groups and analyzed. The primary outcome was the composite of death, myocardial infarction, or stroke.”
Upon a series of analyses, PCI was found to be associated with a higher risk for the primary composite outcome of death, MI, or stroke, when compared with CABG, in patients with moderate (hazard ratio [HR], 2.23; 95% confidence interval [CI]: 1.17 to 4.28) or severe (HR, 2.45; 95% CI: 1.27 to 4.73) LV dysfunction (Figure). However, the risk for the composite outcome was comparable between PCI and CABG in those with normal (HR, 0.80; 95% CI: 0.59 to 1.07) or mild (HR, 1.17; 95% CI: 0.63 to 2.17) left ventricular dysfunction. There was a significant interaction between the severity of LV dysfunction and the relative treatment effect of the revascularization strategy. Observed (unadjusted) rates for the primary and secondary outcome are shown in the Table.
An Essential Consideration
“Since lower LVEF appeared to be an independent predictor for hard clinical endpoints and a significant interaction was present between the severity of LV dysfunction and relative treatment effect of revascularization strategy (CABG vs PCI), the severity of LV dysfunction should be essentially considered in the decision making related to the optimal revascularization strategy for LMCA disease,” explains Dr. Park. “For patients with moderate or severe LV dysfunction, CABG should be considered as the first choice of revascularization strategy, if the surgical risk is acceptable.”
With the study subject to potential biases due to inherent methodologic limitations of a nonrandomized, observational study and the small proportion of patients with moderate or severe LV dysfunction potentially limiting the precision of the treatment effect in these groups, Dr. Park suggests that the findings—especially those of patients with severe LV dysfunction—be confirmed through further larger, clinical trials. “The impact of complete revascularization and myocardial viability on clinical outcomes of patients with LMCA disease and LV dysfunction, which could not be evaluated in our study, is also needed to be adequately addressed by further studies,” he adds. “Additionally, the selective or routine use and its protective role of mechanical circulatory support for high-risk PCI in patients with LMCA disease and severe LV dysfunction should be addressed through further clinical research.”
PWeekly