Functional measurement of intermediate coronary stenosis using fractional flow reserve: Based Technique
Abstract
Background: Coronary angiography has limited ability to determine the functional significance of intermediate coronary lesions. Fractional flow reserve (FFR) provides a physiological assessment that can complement angiographic evaluation. Objective: To evaluate the relationship between FFR and angiographic severity assessed by visual estimation and quantitative coronary angiography (QCA) in intermediate coronary lesions. Methods: This cross-sectional observational study included 43 consecutive symptomatic patients with 53 intermediate coronary lesions evaluated at the catheterization laboratory of Ibn Al-Bitar Center for Cardiac Surgery and Cardiology between July and December 2013. Diameter stenosis was assessed visually by two interventional cardiologists and by QCA. Lesions were classified according to QCA into Group A (50–70% stenosis; 29 lesions) and Group B (30–49% stenosis; 24 lesions). FFR was measured during maximal hyperemia induced by intravenous or intracoronary adenosine using a pressure-wire system. A lesion was considered functionally significant when FFR was ≤0.80. Results: Mean FFR was 0.87 ± 0.068 (range, 0.65–0.99). FFR was ≤0.80 in 5 of 29 lesions (17%; 95% confidence interval [CI], 6–36%) in Group A and in none of the 24 lesions in Group B (0%; 95% CI, 0–14%). The difference between groups was not statistically significant (Fisher’s exact test, P = 0.056), and agreement between angiographic group and FFR category was slight (κ = 0.16). QCA diameter stenosis showed a weak inverse correlation with FFR (r = −0.40, P = 0.003). Mean diameter stenosis was 50 ± 10.25% by QCA and 57 ± 11.14% by visual assessment. Adenosine-related adverse effects were predominantly minor; chest discomfort occurred in 15 patients (34.9%) and bradycardia below 50 beats/min in 8 (18.6%). No death or myocardial infarction occurred. Conclusion: Angiographic severity showed only a weak relationship with the physiological significance of intermediate coronary lesions in this small single-center study. FFR may provide additional information when angiography alone is insufficient to determine lesion significance, although larger studies with clinical follow-up are required