Invasive Treatment of Left Main Coronary Artery Disease: From Anatomical Features to Mechanistic Differences

There is debate on the best treatment for significant stenoses of the left main (LM) coronary artery. The available evidence is based on four randomized trials, which were either performed specifically to assess patients with LM disease (EXCEL, NOBLE, PRECOMBAT) or had a significant fraction of patients with this disease pattern (SYNTAX). A meta-analysis revealed no difference in periprocedural and 5-year mortality but demonstrated a significant reduction of spontaneous myocardial infarction (MI) with CABG. Furthermore, the recently published SWEDEHEART registry data have shown survival advantage and fewer MACCE with CABG for LM disease after adjustment. In general, patients with more severe coronary artery disease (CAD) appear to have a survival advantage with CABG both over PCI and medical therapy (independent of the presence or absence of LM stenosis), which is always associated with a reduction of spontaneous MI in the CABG arm. Since the nomenclature of LM disease does not automatically reflect the complexity of CAD, we review the nature of LM disease in this article. We mechanistically assess the treatment effects of PCI and CABG for patients with LM disease, which is rarely isolated, often distal, and mostly associated with varying degrees of single and multi-vessel disease. We conclude that in patients with isolated LM shaft lesions and associated diseases of low complexity, the risk of spontaneous MI is lower, and PCI may achieve similar long-term outcomes compared to CABG. Thus, heart teams are essential for selecting the best treatment option and should focus on assessing infarction risk in chronic CAD.