Aims: The study aimed to examine five-year clinical outcomes of complete (CR), partially complete (PCR), and incomplete revascularisation (ICR) in patients with unprotected left main coronary artery (ULMCA) disease treated with drug-eluting stents (DES). Completeness of revascularisation, defined as revascularisation of all vessels ≥1.5 or 2.5 mm in diameter, has been shown to correlate with outcomes after percutaneous coronary intervention (PCI). There are no data to compare revascularisation strategies on long-term clinical outcomes in patients undergoing PCI of ULMCA disease. Methods and results: This prospective registry enrolled 910 consecutive patients with ULMCA disease undergoing PCI with DES implantation. CR included patients who had a successful revascularisation of all diseased segments with diameter ≥1.5 mm. PCR included patients who had successful revascularisation of all diseased segments with diameter ≥2.5 mm. ICR included patients who did not achieve revascularisation for all diseased segments of diameter ≥2.5 mm. The primary endpoint was the incidence of major adverse cardiac events (MACE: a composite of cardiac death, myocardial infarction and repeat revascularisation) at five-year follow-up. CR was achieved in 386 (42.4%), PCR in 227 (25.0%), and ICR in 297 (32.6%) patients. Patients with ICR had a significantly higher rate of MACE (29.6% vs. 22.5% and 15.5%, p<0.001) and all-cause mortality (12.5% vs. 7.0% and 6.2%; p≥0.006) than those with CR and PCR at five-year follow-up. After propensity score matching, patients with CR vs. PCR had similar incidences of MACE (hazard ratio [HR]: 1.16, 95% confidence interval [CI]: 0.78-1.74, p≥0.46), mortality (HR: 1.27, 95% CI: 0.61-2.63, p≥0.53), and cardiac death (1.8% vs. 4.5%; HR: 2.56, 95% CI: 0.80-8.17, p≥0.11). On multivariable logistic regression analysis, ICR appears to be an outcome of poor clinical characteristics, comorbidities and complex coronary anatomy. Conclusions: In the treatment of patients with ULMCA disease, ICR was associated with worse long-term clinical outcomes than CR and PCR. PCR has clinical outcomes similar to CR in patients with ULMCA disease treated with DES.
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