Objectives: To investigate the relationship between classic SYNTAX and functional SYNTAX score guided by fractional flow reserve (FFR).
Background: SYNTAX score predicts clinical outcome after percutaneous coronary intervention in patients with multivessel coronary artery disease (CAD), based on data from angiography alone. However, in the clinical setting, decision-making on myocardial revascularization should be guided by reliable demonstration of inducible ischemia, as detected by FFR.
Methods: FFR was collected in all 50-90% angiographic stenoses of 39 consecutive patients with stable multivessel CAD. SYNTAX score was calculated as usually described in SYNTAX group's reports. A functional SYNTAX (F-SYNTAX) score was determined by only considering ischemia-producing lesions (FFR ≤ 0.80). The two scores were compared with correlation, Bland-Altman and agreement tests.
Results: FFR was measured in 97 lesions, with a median value of 0.82±0.10. In the 50-70% and 70-90% category stenoses, FFR was greater than 0.80 in 68 and 16% of cases, respectively. F-SYNTAX was systematically inferior to SYNTAX score, with a median difference of 8.4±7.4 (P<0.05). The correlation between the two methods was globally weak (r=0.621, rho=0.563; P<0.001). After determining F-SYNTAX score, more than 30% of the patients moved to a lower-risk tertile group (P=0.003). No clinical and angiographic differences were found between patients whether or not reclassified in lower-risk tertiles with F-SYNTAX score.
Conclusions: In patients with multivessel CAD, implementation of SYNTAX score with FFR seems to be a more rational approach for revascularization. F-SYNTAX score reclassifies a significant proportion of patients to a lower-risk profile, thus leading to a possible change of therapeutic strategy.