Physiological assessment of left circumflex coronary artery. A bicentric validation and outcome study using μFR

Lesions of the left circumflex artery (LCx) and its obtus marginal (OM) branches, are often challenging to assess physiologically by fractional flow reserve (FFR) due to anatomical and hemodynamic nuances. µFR is a virtual FFR analysis software based on a single angiographic view, and has been validated versus standard Quantitative Flow Reserve (QFR).

We sought to assess the accuracy of μFR versus FFR and its prognostic impact in PCI within the LCx/OM territory.

A retrospective, international, bicentric study with corelab analysis was conducted, including patients who underwent either invasive physiological assessment or PCI of LCx and/or OM. Major adverse cardiac events (MACE) were defined as the composite of cardiovascular death and target vessel failure (myocardial infarction or revascularization related to the LCx/OM territory).

A total of 432 patients (150 physiological assessment only and 282 PCI) were enrolled. Only 5.1 % of intermediate LCx/OM lesions were positive on FFR. Good correlation and agreement were found between μFR and FFR (R = 0.782, p < 0.001); mean difference: -0.029 ± 0.035, p = 0.301). Among patients who underwent LCx/OM PCI, only 18.8 % had positive μFR. Cardiovascular outcome was similar between patients with μFR positive and μFR negative LCx/OM lesions who underwent PCI. In patients with negative μFR, PCI did not impact MACE occurrence (HR 1.20, 95 %CI 0.41-3.23, p = 0.771).

µFR demonstrates good diagnostic agreement with invasive FFR for LCx/OM lesions. Most LCx/OM lesions treated with PCI were physiologically non-significant, and revascularization in this context did not improve clinical outcomes.