Prognosis of deferred non-culprit lesions according to fractional flow reserve in patients with acute coronary syndrome

There are limited data on the prognosis of deferred non-culprit lesions in patients with acute coronary syndrome (ACS) based on fractional flow reserve (FFR). We aimed to investigate the prognosis of deferred non-culprit lesions in ACS patients, compared with deferred lesions in patients with stable coronary artery disease (SCAD), on the basis of FFR.The clinical outcomes of 449 non-culprit lesions (301 patients with ACS) were compared with 2,484 lesions (1,295 patients with SCAD) in which revascularisation was deferred on the basis of a high FFR (>0.80). The primary outcome was major adverse cardiac events (MACE), a composite of cardiac death, target vessel-related myocardial infarction (MI) and ischaemia-driven revascularisation. Among the ACS population, 65.8% presented with unstable angina and 34.2% with non-ST-segment elevation MI. Mean angiographic percent diameter stenosis and FFR of the deferred lesions were 39.3±15.0% and 0.92±0.06, respectively. During the median follow-up duration of 722.0 days, the deferred non-culprit lesions of ACS patients showed a significantly higher rate of MACE (3.8% vs. 1.6%, HRadj 2.97, 95% CI: 1.23-7.17, p=0.016), mainly driven by the higher rate of ischaemia-driven revascularisation (2.8% vs. 1.1%, HRadj 3.39, 95% CI: 1.29-8.92, p=0.013) than the deferred lesions in SCAD patients. Regardless of the range of FFR in the deferred lesions (0.81-0.85, 0.86-0.90, 0.91-0.95, and 0.95-1.00), non-culprit lesions of ACS showed a more than twofold higher rate of MACE than that of SCAD. In a multivariable marginal Cox model, ACS was the most powerful independent predictor of MACE (HRadj 2.74, 95% CI: 1.13-6.64, p=0.026).Compared to the deferred lesions of SCAD patients, deferred non-culprit lesions of ACS on the basis of FFR showed a higher rate of clinical events, regardless of FFR range.