A novel index reflecting both anatomical and physiologic parameters in coronary artery disease, the FFR adjusted SYNTAX score (FaSs)

Abstract Background Various physiology-based indices have been proposed to predict adverse clinical events in patients with coronary artery disease (CAD), such as the sum of three vessel-fractional flow reserve (3v-FFR), and the functional SYNTAX score (fSS). However, these values could not fully reflect the anatomical factors, which remains as a barrier for clinical application of these indices. Purpose To propose a novel index which can reflect both anatomical and physiologic features in CAD patients, and evaluate the additional predictive value for cardiovascular adverse events compared to previous indices. Methods For an index which can reflect both anatomical and physiologic features, we proposed the FFR adjusted SYNTAX score (FaSs). The FaSs is calculated by adding the product of the SYNTAX score and `1-FFR', for all three major coronary arteries. Among the 1136 patients who enrolled at 3V FFR-FRIENDS study, we investigated 866 patients, after excluding those who had missing variables. The 3v-FFR, fSS and FaSs were calculated, derived from the baseline FFR and SYNTAX score. Patients were divided into two groups according to the median value of each index. The primary endpoint was major adverse cardiac events (MACE, a composite of cardiac death, myocardial infarction and ischemia-driven revascularization) at 2 years follow-up. Results Among the total population, MACE occurred in 35 (4.04%) patients. Using the median value in a multivariable COX regression model, only FaSs was associated with an increased risk of MACE, (Hazard Ratio [HR] 5.256, 95% confidence interval [CI] 2.014–13.720), while 3v-FFR (HR 1.383, 95% CI 0.685–2.790) and fSS (HR 1.640, 95% CI 0.830–3.243) were not significantly associated with a higher risk of MACE. This was also observed in the Kaplan Meier survival curve analysis (log-rank p value: p<0.001 for FaSs, 0.153 for 3v-FFR, and 0.061 for fSS; Figure 1) The sensitivity and specificity of the FaSs was 85.7% and 51.6%, which was higher compared to the 3v-FFR (62.9% and 49.3%, respectively) and fSS (57.1% and 58.5%, respectively). When these indices were combined with clinical risk factors (age, sex, hypertension, diabetes, hyperlipidemia, chronic renal failure, LVEF<40%), FaSs was superior compared with 3v-FFR and fSS assessed in regards of the predictive accuracy for MACE (Figure 2). Conclusion The FaSs, which is a novel index calculated by a formula using the SYNTAX score and FFR, showed a superior predictive value for MACE compared to previous indices. Our results confirm the importance of considering both anatomical and physiologic parameters in evaluating the patient's risk for cardiovascular adverse outcomes. Funding Acknowledgement Type of funding sources: None.