Comparison between fractional flow reserve and visual assessment for moderate coronary artery stenosis

Aim: "Fractional Flow Reserve" (FFR) is a major interventional diagnosis tool for the assessment of hemodynamic importance of coronary stenosis severance through intracoronary pressure measurement. However, FFR is not a common in daily practice as visual assessment is a more frequently administered method. This study aims at comparing the assessment of severity of moderate stenosis in CAG via FFR to visual assessment through multiple observers. Method: Patients who applied to our hospital between January 2011 and August 2014 and administered with coronary angiography, diagnosed with a moderate coronary artery lesion, and then administered with FFR were scanned as a part of this study. The study included clinically stable and unstable coronary artery patients, and patients who applied with a complaint of STEMI who were administered with a primary percutaneous intervention, and then with the FFR for the lesion not related to infarction. Angiographic images of 359 patients were separately interpreted by three interventional cardiologists (G1, G2, G3) who were appointed as observers. Observers were not provided with information about demographic details, risk factors, clinical features, FFR results and post-FFR decisions. Lesions were classified by the observers as "severe", "not severe", and "undecidable". Findings: Out of 359 patients of the study, 73.6% of them were male while their mean age was 62.6±10.1 years. Following the diagnostic CAG, it was concluded that 43.6% of patients suffered from one vascular disease while 32.5 suffered from two vascular diseases. And the remaining 23.9% suffered from three vascular diseases. Administered for moderate stenosis, FFR pointed out that 37.9% of the results were hemodynamically significant while 62.1% were not. Observers decided to go with the PCI for the lesion administered with FFR for 22.2% of the patients, and with CABG for the 17.2%. 40.3%, 39.9% and 44.4% of the moderate lesions were interpreted as severe by G1, G2 and G3 respectively. When observers' decisions with regard to the severity of lesions were compared to FFR results, the severity percentages identified by each of the three observers were significantly different than both each other and the FFR results p<0.001, p<0.001, respectively). As a result of Kappa analysis carried out for the agreement of observers with FFR in terms of lesion severity, it turned out that the FFR results and the results for G1, G2 and G3 were significantly different (p<0.001). Upon the Kappa analysis carried out by matching the decisions of the observers in doubles, G1 and G2 turned out to have a good agreement between each other while the agreement among the G2 and G3 as well as the G1 and G3 were moderate, and a statistically significant disagreement persisted (p<0.001). Conclusion: To identify the functional importance of moderate coronary artery stenosis, the visual assessment does not yield similar results with the FFR procedure even if it is conducted by experienced interventional cardiologists. Within the technical bounds of possibility, one should opt for FFR rather than an assessment of multiple observers for the assessment of severity of moderate coronary lesions. Keywords: Fractional flow reserve, visual assessment, moderate lesions