Impact of the metal-to-artery ratio on clinical outcomes in left main and nonleft main bifurcation: insights the RAIN-CARDIOGROUP VII study (veRy thin stents for patients with left mAIn or bifurcatioN in real life).

Introduction: The impact on clinical outcomes of the metal coverage on the coronary surface (namely the metal-to-artery ratio) of currently used drug-eluting stents (DESs) has not been defined.

Methods: All patients with a left main or bifurcation stenosis treated with percutaneous coronary intervention (PCI) using ultrathin stents (struts thinner than 81 μm) were enrolled with a prospective multicentre fashion. The rate of device-oriented endpoint [DOE, defined as a composite of target lesion revascularization (TLR) and stent thrombosis] was the primary endpoint, while its single components were the secondary ones, evaluated according to the metal-to-artery ratio.

Results: After 14 ± 10.4 months 62 (7.5%) of 830 patients undergoing PCI on left main experienced a DOE without differences in the metal-to-artery ratio (14.5 ± 2.1 vs. 14.4 ± 1.9, P = 0.51). Fifty out (2.4%) of 2082 patients treated with PCI on a coronary bifurcation other than left main experienced a DOE, with a higher mean metal-to-artery ratio (15.3 ± 2.1 vs. 14.6 ± 2, P = 0.01). At multivariate analysis, together with hypertension and diabetes, the metal-to-artery ratio was an independent predictor of DOE (hazard ratio 1.7 : 1.02-1.34, P = 0.02) in nonleft main PCI. When analysed for diameter, we found a significant correlation with DOE when the stent diameter was inferior to 3.0 mm (hazard ratio 1.21: 1.06-1.38, P < 0.01, all 95% confidence interval); this result was mainly consistent for patients treated with provisional stenting. The metal-to-artery ratio does not impact on outcomes in left main PCI, both in the provisional or two-stent technique, and generally when a drug-eluting stent more than 3.5 mm in diameter is implanted. Regarding nonleft main PCI, it is independently related to DOE and TLR, especially for DES with a diameter of 3.25 mm or less.

Conclusion: The metal-to-artery ratio does not impact on outcomes in left main PCI, both in the provisional or two-stent technique, and generally when a drug-eluting stent more than 3.5 mm in diameter is implanted. Regarding nonleft main PCI, it is independently related to DOE and TLR, especially for DES with a diameter of 3.25 mm or less.