Left main stem (LMS) disease is identified in up to 5 % of diagnostic angiography cases.1 It has major prognostic significance due to the proportion of myocardium at risk. Many years ago, the Coronary Artery Surgery Study (CASS) registry demonstrated the superiority of coronary artery bypass grafting (CABG) over medical therapy with a 5-year mortality reduction from 43 % to 16 % in symptomatic patients.2 Since the advent of coronary angioplasty, interventional cardiologists have sought to assess the role of percutaneous treatment of LMS disease. Advances in stent technology, implantation techniques, ancillary imaging and pharmacotherapy have increasingly made this prospect a reality.
Early Experience
The third patient treated by Andreas Gruntzig back in 1979 had LMS balloon angioplasty. The technical result was satisfactory but the patient unfortunately died suddenly 4 months post-procedure.3 In the 1980s, the limitations of ‘plain old balloon angioplasty’ (POBA) in the treatment of LMS disease became apparent. O’Keefe and colleagues showed a 64 % 3-year mortality rate when LMS disease was treated with balloon angioplasty4 and the practice was almost wholly abandoned. Interest in percutaneous treatment was only revived with the introduction of bare metal stents (BMS) and the advent of newer anti-platelet therapies aimed at reducing in-stent restenosis (ISR) and thrombosis.
In the 1990s, promising LMS stent results were published though most stemmed from single centres. Silvestri et al. reported a 1-year survival of 89 % in a high-risk subgroup of patients,5 while Park et al. reported a 91 % 3-year survival rate in a multicentre study.6 The Unprotected Left Main Trunk Intervention Multi-Center Assessment (ULTIMA) registry evaluated the procedural and clinical outcomes after unprotected LMS percutaneous coronary intervention (PCI) was undertaken in 25 centres.7 This showed an overall 24 % 1-year mortality with a better outcome in low-risk groups and only a 3.4 % mortality rate at 1 year. As drug-eluting stents (DES) entered the interventional arena, several centres began reporting their experience in LMS lesions. A systematic review of 1,278 patients by Biondi-Zoccai et al. in 2008 showed that PCI was associated with a 5.5 % risk of death on average and a major adverse cardiac event (MACE) rate of 10.6 %.8