Analysis Finds CABG Bests PCI for CAD Patients with Severely Reduced LVEF

Louise Sun, MD

A new study from the University of Ottawa Heart Institute intervention (PCI) and coronary artery bypass grafting (CABG) for patients with severely reduced left ventricular ejection fraction (LVEF).

Results of the retrospective study suggest PCI may be associated with a greater risk of mortality and major adverse cardiovascular events than CABG in this under-researched patient population.

To evaluate potential differences in outcomes for patients with coronary artery disease (CAD) with severely reduced LVEF requiring revascularization, a team of investigators led by Louise Sun, MD, assistant professor of Anesthesiology and Pain Medicine, designed a retrospective cohort study using CorHealth Ontario registry data of patients undergoing their first myocardial revascularization over an eight-year period from October 2008 through 2016.

In total, 12,113 patients were identified but only 4794 were included in the propensity-matched analysis.

For inclusion in the study, patients needed to be between 40-84 years of age and have an LVEF of <35%. Patients were also required to have 50% or greater stenosis in the left main artery, 70% or greater stenosis in the left anterior descending (LAD) artery, or 70% or greater stenosis in 2 or more major epicardial arteries. Investigators noted the exclusion of non-Ontario residency, concomitant procedures, emergency revascularization within 24 hours of presentation, dialysis dependency, and presence of metastatic malignant tumor.

The primary outcome of the analysis was all-cause mortality. Secondary outcomes included death from cardiovascular disease and MACE, which was defined as stroke, subsequent revascularization, or hospitalization for myocardial infarction (MI) or heart failure (HF), and each of the individual MACE outcomes.

In total, 2397 patients were included in both of the propensity-matched cohorts for both procedures. Analysis of the PCI group revealed the mean number of stents implanted per patient was 1.9 (1.1) and mean wait time from diagnostic coronary angiogram to PCI was 4.1 (9.7) days. In the CABG group, mean number of grafts placed per patient was 3.3 (1.0) and mean wait time from diagnostic coronary angiogram to CABG was 14.5 (25.3) days.

Investigators noted the mean PCI volume was 265.6 (119.5) cases per year among interventional cardiologists and the mean (SD) CABG volume was 135.0 (54.0) cases per year among surgeons during the study period.

At 30 days, patients in the PCI arm experienced greater rates of all-cause mortality (4.8% vs 4.0%), death from cardiovascular disease (3.5% vs 2.8%), MACE (19.8% vs 8.3%), subsequent revascularization (10.9% vs 3.2%), and hospitalization for MI (7.8% vs 1.4%) or HF (5.6% vs 3.0%). Results suggest risk among subgroups defined by the presence of diabetes, the number of diseased vessels, and completeness of revascularization, indicate 30-day risk of MACE were constantly higher in patients undergoing PCI.

Mean follow-up for the 2 cohorts was 5.2 years and during the follow-up, 5-year mortality rates were 30.0% in the PCI group and 23.3% in the CABG group. Results indicated patients who underwent PCI had a higher risk of mortality (HR, 1.6; 95% CI, 1.4-1.7), death from cardiovascular disease (HR, 1.4; 95% CI, 1.1-1.6), MACE (HR, 2.0; 95% CI, 1.9- 2.2), subsequent revascularization (HR, 3.7; 95% CI, 3.2-4.3), hospitalization for MI (HR, 3.2; 95% CI, 2.6-3.8), and hospitalization for HF (HR, 1.5; 95% CI, 1.3- 1.6) compared to patients who underwent CABG.

Conversely, results suggest risk of stroke was lower for patients who underwent PCI (HR, 0.7; 95% CI, 0.5-0.9) compared to those who underwent CABG.

In an invited commentary published in JAMA Cardiology, Eric Velazquez, MD, of the Yale School of Medicine, highlighted the lack of data surrounding this topic and how valuable it makes the investigators’ analysis.

“The role of PCI compared with either medical therapy alone or against CABG is markedly understudied in patients with LV dysfunction, as the numbers of such patients included in randomized PCI trials is miniscule,” Velazquez wrote. “What to our knowledge is the first trial comparing PCI with medical therapy in such patients is still underway."

As such, he wrote, the accompanying cohort study is "not only welcome but actionable.”

The study, “Long-term Outcomes in Patients With Severely Reduced Left Ventricular Ejection Fraction Undergoing Percutaneous Coronary Intervention vs Coronary Artery Bypass Grafting,” was published online in JAMA Cardiology.