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The discordant relationship between fractional flow reserve (FFR) and coronary flow reserve (CFR) is incompletely understood. We performed a study to assess the contributions of microcirculatory disease and residual epicardial disease to this relationship.
Consecutive patients undergoing PCI for stable angina and stabilized NSTEMI with single vessel disease were included in the study. FFR, index of microcirculatory resistance (IMR) and CFR were measured using a pressure wire pre and post PCI. A CFR value ≤2.0 and an FFR ≤0.8 were used as thresholds for ischaemia.
84 patients (mean±SD) age 60.5±11.3 years, 78% male, 35% NSTEMI were included. CFR and FFR were correlated (r=0.48, p=0.001) [Figure 1]. There was no difference in coronary physiological parameters (IMR, CFR and FFR) between NSTEMI and SA. In 70.2% of cases CFR and FFR were concordant. Using FFR as a gold standard the PPV and NPV for CFR was 87% and 39% respectively. There was no significant difference in IMR or post PCI FFR comparing patients with a FFR>0.8 and CFR≤2.0 and >2.0. In patients with an FFR ≤0.8 but a CFR >2.0 and CFR≤2.0, there was also no significant differences (Figure 1). Although linear regression demonstrated that FFR pre PCI predicted CFR (p<0.0001) the model had limited power (r2 0.29) suggesting other factors are important in determining CFR.
The discordant relationship between CFR and FFR is not explained by differences in microvascular disease or residual culprit epicardial disease.
Poster Sessions, Expo North
Sunday, March 10, 2013, 9:45 a.m.–10:30 a.m.
Session Title: Physiological Assessment
Abstract Category: 38. TCT@ACC–i2: Intravascular Imaging and Physiology
Presentation Number: 2107–224
- 2013 American College of Cardiology Foundation