Extended follow-up of MAIN-COMPARE, do we have final winners for the never-ending debate?

For years, the best modality of managing LM disease (CABG or PCI) has been vigorously debated. Earlier, the MAIN-COMPARE (Revascularization for Unprotected Left Main Coronary Artery Stenosis: Comparison of Percutaneous Coronary Angioplasty Versus Surgical Revascularization) registry, reported that CABG showed lower mortality and serious composite outcome rates compared with PCI with drug-eluting stents (DES) when follow-up was extended from 5 to 10 years. However, the debate regarding mortality benefit with CABG continues, in light of emerging long-term data.

Against this backdrop Hyun et al. compared the outcomes for CABG versus PCI in patients with lesions located in the ostium or the shaft versus lesions located at the distal LMCA bifurcation at a median follow-up of 12 years.

Patients from the MAIN-COMPARE registry were analyzed, comparing adverse outcomes (all-cause mortality [a composite outcome of death, Q-wave myocardial infarction, or stroke] and target vessel revascularization) between PCI and CABG according to LMCA lesion location during a median follow-up period of 12.0 years.

Ostial and mid-shaft LMCA lesions were treated by PCI or CABG in 557 and 526 patients, respectively, whereas distal LMCA bifurcation lesions were treated with PCI or CABG in 545 and 612 patients, respectively. Concomitant 3-vessel disease was present in 30% of patients with ostial and shaft lesions and in 45% of patients with distal bifurcation LMCA lesions. The risk of target-vessel revascularization was consistently higher in patients who were treated with PCI versus CABG.

After 5 years and only in patients with distal LMCA bifurcation lesions, the risks of all-cause mortality (hazard ratio: 1.78; confidence interval: 1.22 to 2.59; p = 0.003) and the composite risk of death, Q-wave myocardial infarction, and stroke (hazard ratio: 1.94; confidence interval: 1.35 to 2.79; p < 0.001) were higher when treated with PCI using DES. The higher incidence of adverse events was mainly driven by the 2-stent strategy group.

The authors concluded that among patients with distal LMCA bifurcation disease, CABG showed lower mortality and serious composite outcome rates compared with DES beyond 5 years. However, there were no between-group differences in these outcomes among patients with ostial or shaft LMCA disease.

JACC editor Antonio Colombo noted "We believe that the negative outcomes observed for distal LMCA bifurcation lesions treated with PCI are strongly affected by the presence of more advanced disease beyond the LMCA. A careful evaluation of the data reveals that distal LMCA bifurcation disease was more frequently associated with triple vessel coronary disease and a higher SYNTAX score. Therefore, the elevated atherosclerotic burden of these groups of patients potentially represents complex systemic disease, which is more challenging to treat and to achieve a durable result with stent implantation."

"We believe that the terminology "distal LM bifurcation lesion" category is too simplistic. The clinical impact of a distal LM bifurcation lesion is dependent on the circumflex coronary artery, which could have focal ostial disease, be of small caliber, or be a dominant vessel with long diffuse disease. These anatomic and pathological variants can influence the decision to stent, the type of stent technique, or CABG", he adds.

Source: JACC cardiovascular interventions.Hyun J., Kim J., Jeong Y., et al."Long-term outcomes after PCI or CABG for left main coronary disease according to lesion location". J Am Coll Cardiol Intv 2020;13:2825-2836.