New randomized comparison of unprotected left main coronary artery stenting and CABG

February 2, 2008 By Benjamin A. Olenchock, M.D. Ph.D. [mailto:bolenchock@partners.org]

A new study published in the Journal of the American College of Cardiology has randomized patients with left main coronary artery disease to undergo unprotected left main coronary artery (ULMCA) stenting or coronary artery bypass grafing (CABG). Currently, CABG is the standard of care for the treatment of left main coronary artery disease. However, there have been numerous reports of good outcomes following coronary angioplasty and stenting. Advocates of ULMCA stenting suggest that this technique is a safe, less morbid alternative to open heart surgery. Critiques are concerned about the procedural risks associated with inflating balloons in such a proximal artery, as well as the devastating consequences of in-stent thrombosis in such a location. Ongoing randomized trials have in this field have been criticized for focusing on short-term outcomes, which might be predicted to favor percutaneous intervention (PCI).

Researchers in Poland, Texas and Pennsylvania screened 347 patients with left main disease, defined as a greater than 50% narrowing of the left main disease. Patients were unprotected, meaning that they did not have a graft supplying distal blood flow. All patients were symptomatic and had documented ischemia. Exclusion criteria included patients with myocardial infarctions (MI), recent stroke, kidney disease, contraindications to anti-platelet therapies, and anatomic and surgical risk characteristics that made them inappropriate for randomization. The final exclusion criteria were determined by a joint decision between interventionalists and surgeons leading the study. The primary endpoint was change in left ventricular ejection fraction (LVEF) at 12 months after revascularization, and secondary endpoints included 30-day major adverse events (MAE; all-cause mortality, acute MI, repeat revascularization, heart failure, requirement for pressors or balloon pump, arrhythmia-including atrial fibrillation, major bleed or infection), major adverse cardiac and cerebrovascular events (MACCE; cardiac mortality, MI, stroke, repeat intervention and stent thrombosis), length of hospitalization, target vessel failure, angina severity and exercise tolerance at 1 year, and total MACCE-free survival.

Only 122 patients were eligible for the study and underwent randomization. Baseline characteristics were similar between treatment arms. Around 20% of patients were diabetic, most had 3 vessel disease (60% in PCI, 75% in CABG). There was angiographic success of revascularization in all PCI patients, and clinical evidence of success in almost all patients in both arms (98% in PCI vs. 92% in CABG, p=0.4). Hospitalization was longer in the CABG group (12 vs. 7 days, p<0.001). For early outcomes, PCI was associated with lower occurrence of MAE (8% vs 28%, p=0.006) and MACCE (2% vs 13%, p=0.03). Early MAE appears to be driven by higher numbers of death (0 vs. 2), infection/post-cardiotomy syndrome/sternal refixation (0 vs. 7), and arrhythmia (1 vs. 3) in the CABG arm. Late outcomes were similar between treatment arms. LVEF was higher in the PCI group at 12 months (58% vs. 54%, p=0.01), and change in LVEF was significantly greater in the PCI arm than in the CABG arm (3.3% vs. 0.5%, p=0.047). One-year survival was similar (98% in PVI, 93% in CABG) and long-term (3-4 yr follow-up) MAE and MACCE were statistically similar. There was a trend towards improved long-term survival in the PCI arm (p=0.08). There was no occurrence of stent thrombosis in this trial.

This study demonstrated remarkable success in selected patients for ULMCA stenting, with 1-year outcomes similar to that after CABG. Additionally, LVEF was better in patients randomized to the PCI arm. The exclusion criteria might limit the generalizability of their findings, however it also gets at the core issue involved in this debate: clinical judgment as to patient suitability for PCI vs. CABG is an important consideration in real life decisions. There are anatomical and surgical risk considerations that might be difficult to standardize for clinical trials. The differences in short-term outcomes were as expected, and the trend towards improved outcomes with ULMCA stenting is interesting. As the authors note, larger long-term trials will be necessary to answer this question.