Prognostic value of computational pressure-flow dynamics derived fractional flow reserve among non-ST-elevation myocardial infarction and unstable angina patients

Computational pressure-flow dynamics derived fractional flow reserve (caFFR) is a novel index to assess the severity of coronary artery stenoses without requirement of invasive pressure wire and hyperaemic stimulus in fractional flow reserve (FFR) measurement. Non-ST-elevation myocardial infarction (NSTEMI) and unstable angina (UA) is the most and second most common acute coronary syndrome, respectively. However, whether selective PCI guided by caFFR in addition to angiography can provide further clinical benefit is unclear for patients presenting with NSTEMI and UA. The aim of this study is to investigate the prognostic value of caFFR among NSTEMI and UA patients. A total of 1449 vessels in 483 patients that presented with NSTEMI or UA (mean age=67.0±12.3, 67.9% male) were retrospectively analysed for caFFR. Patients had undergone PCI according to the angiographic and clinical data available at the time. Vessels were said to be adherent to caFFR if ischemic vessels, defined by caFFR≤0.8 had been treated with PCI and non-ischemic vessels, defined by caFFR>0.8 had not been treated by PCI. Otherwise, they were considered non-adherent to caFFR. The primary endpoint was the vessel-oriented composite endpoint (VOCE), defined as vessel-related cardiovascular mortality, vessel-related myocardial infarction (MI) and unplanned revascularisation at median 4.4 years follow-up. Survival curves were constructed using Kaplan-Meier estimates and differences between groups were tested using the log-rank test. Cox proportional hazards model was used to evaluate the association between adherence to caFFR and the risk of VOCE, with parameters with P<0.1 upon univariate analysis entered into multivariable Cox model. Among the 1449 vessels, caFFR was analysable in 1020 (70.4%) vessels, with 802 (78.6%) vessels that received treatment adherent to caFFR and 218 (21.4%) vessels that received treatment non-adherent to caFFR. Adherent vessels had significantly lower incidence rates of VOCE (11.2% vs 18.3%; P=0.005) and MI (2.0% vs 9.2%, P<0.001) compared to non-adherent vessels. This was primarily driven by reductions in the incidence of VOCE (18.0% vs 28.9%; P=0.026) and MI (2.4% vs 15.7%; P<0.001) in ischemic vessels that underwent PCI compared to ischemic vessels that did not undergo PCI. After multivariate adjustment, adherent vessels had a significantly lower risk than non-adherent vessels in terms of VOCE (HR 0.59; 95%[Cl] 0.41-0.86; P=0.006) and vessel-related MI (HR 0.22; 95%Cl 0.11-0.42; P<0.001). In patients presenting with NSTEMI or UA, revascularization that was adherent to caFFR guidelines was associated with a significant reduction in VOCE. The findings support the potential use of caFFR in treatment guidance of NSTEMI and UA patients. Kaplan-Meier plots for VOCE Kaplan-Meier plots for vessel-related MI