Importance of Diffuse Atherosclerosis in the Functional Evaluation of Coronary Stenosis in the Proximal-Mid Segment of a Coronary Artery by Myocardial Fractional Flow Reserve Measurements

The objective of this study was to evaluate the impact of diffuse coronary atherosclerosis on the functional evaluation of moderate coronary lesions in the proximal-mid segment of a coronary artery and its clinical implications. This was a prospective study including 100 consecutive patients with a moderate lesion (45 ± 9% diameter stenosis) in the proximal-mid coronary segment who were evaluated with fractional flow reserve (FFR) measurement. No patient had any other angiographic stenosis distal to the evaluated coronary stenosis. FFR measurements were obtained just distal (∼2 to 3 cm) to the lesion (FFR proximal measurement [FFR-PM]) and as distally as possible in the artery (FFR distal measurement [FFR-DM]) after administration of the same dose of intracoronary adenosine. Thirty-nine patients underwent dipyridamole or exercise myocardial single-photon emission computed tomography within 3 months of the FFR study. Mean FFR-PM was significantly higher compared to FFR-DM (0.84 ± 0.08 vs 0.78 ± 0.09, median gradient 0.06, 25th to 75th interquartile range 0.02 to 0.10, p <0.0001). FFR-DM was <0.75 in 33% of patients with FFR-PM ≥0.75, leading to the decision of revascularization in these patients. Performing FFR measurement in the left main/left anterior descending artery predicted a higher gradient between FFR-DM and FFR-PM (odds ratio 4.58, 95% confidence interval 1.4 to 15.03, p = 0.007). FFR-DM exhibited a better correlation with results of myocardial single-photon emission computed tomography compared to FFR-PM (kappa 0.33 vs 0.22, p <0.0001). In conclusion, significant differences between FFR-DM and FFR-PM were observed in patients with moderate coronary stenosis in the proximal-mid segment of a coronary artery, with FFR-DM exhibiting a better correlation with results of noninvasive functional tests. These differences influenced the treatment decision in about 1/3 of patients and highlight the potential clinical relevance of coronary pressure wire positioning for functional evaluation of lesions in the proximal-mid segment of the coronary arteries.