The impact of main branch restenosis on long term mortality following drug-eluting stent implantation in patients with de novo unprotected distal left main bifurcation coronary lesions: The Milan and New-Tokyo (MITO) registry

Background In-stent restenosis (ISR) remains one of the main limitations for percutaneous coronary intervention of unprotected distal left main (UDLM). This study aims to demonstrate the impact of main-branch ISR (MB-ISR) on mortality and to clarify the optimal strategy. Methods Between 2002 and 2008, 482 consecutive UDLM patients treated with drug eluting stent (sirolimus and paclitaxel) were evaluated. Results During follow-up period (median 52.6 months), MB-ISR occurred in 29, SB-ISR in 65, and MB/SB-ISR in 24. Multivariable analysis demonstrated that the independent predictors of MB-ISR were calcification (HR 2.284, p=0.016), true-bifurcation (HR 2.331, p=0.024), insulin-dependent diabetes mellitus (insulin-DM) (HR 2.259, p=0.048). Furthermore, final proximal postdilatation (FPPD) (HR 0.548, p=0.077), full LM cover approach (FCA) (HR 0.605, p=0.093) and greater MLD (HR 0.611, p=0.062) had a tendency to reduce MB-ISR. Furthermore, the occurrence of MB-ISR within 1-year was associated with cardiac-death (HR 2.734, p=0.017). Conclusions The patients with MB-ISR had more comorbidities and complex lesions, resulting in higher risk of cardiac mortality as compared to the patients without MB-ISR. Presence of calcification, true-bifurcation and insulin-DM were associated with MB-ISR following UDLM intervention, while FCA, FPPD, and greater MLD seemed to be associated with the low occurrence of MB-ISR.