Frequency of abnormal fractional flow reserve measurements among major coronary arteries.

BACKGROUND: Fractional flow reserve(FFR) is a validated tool for evaluating functional severity and guiding the revascularization of angiographically moderate coronary artery lesions.

OBJECTIVE: To study if there is a higher frequency of positive FFR measurements in the left anterior descending(LAD) versus other major coronary arteries and also evaluate the differences in the total length of the stent placed.

METHODS: A retrospective cohort study including all subjects (January 2011 to December 2015) who had fractional flow reserve (FFR) measured during coronary catheterization was conducted. Coronary catheterizations with FFR at a single tertiary care center were reviewed and FFR ≤ 0.80 post adenosine was deemed positive. The differences in the baseline characteristics and the degree of stenosis were compared between the different vessel groups.

RESULTS: Of the 758 vessels included in the analysis, the majority were LAD(51.3%) followed by right coronary artery(RCA)(22.8%), Circumflex(22.2%), Left main(2.2%), and Ramus intermedius(1.5%). 25.1% of 758 vessels were FFR positive. The proportion of positive FFR were higher among LAD versus other vessels(33.2%vs.16.5%,p < 0.001), while no differences were noted between RCA and circumflex(p = 0.87) or other vessels excluding LAD(p = 0.69). Of 175 patients who received stents, no statistical difference was noted in the median[range] total length of the stent between LAD(22[9-64]) and the other coronary arteries (18[8-42])(p = 0.19). In patients with an FFR <0.75, we found that the stent length(median [range]) was significantly longer in LAD(28[9-42]) than the other coronary arteries(18[8-42])(p = 0.03).

CONCLUSION: In our study, FFR was almost twice as likely to be positive in the LAD when compared to other major coronary arteries. Furthermore, there was a trend towards FFR positive LAD lesions needing longer stents than other coronary arteries. This data should encourage operators to evaluate moderate, long lesions in the LAD with FFR, as they have a higher probability of functional significance.