Disturbed Coronary Hemodynamics in Vessels with Intermediate Stenoses Evaluated with Fractional Flow Reserve: A Combined Analysis of Epicardial and Microcirculatory Involvement in Ischemic Heart Disease
Background—In chronic ischemic heart disease (IHD), focal stenosis, diffuse atherosclerotic narrowings (DAN) and microcirculatory dysfunction (MCD) contribute to limit myocardial flow. The prevalence of these IHD levels in fractional flow reserve (FFR) interrogated vessels remains largely unknown.
Methods and Results—Using intracoronary measurements, 91 coronaries (78 patients) with intermediate stenoses were classified in four FFR and coronary flow reserve (CFR) agreement groups, using FFR>0.80 and CFR<2 as cutoffs. Microcirculatory resistance (IMR) and atherosclerotic burden (Gensini score) were also assessed. MCD was assumed when IMR≥29.1 (75th percentile). Fifty-four (59.3%) vessels had normal FFR, from which only 20 (37%) presented both normal CFR and IMR. Among vessels with FFR>0.80, most (63%) presented disturbed haemodynamics: abnormal CFR in 28 (52%) and MCD in 18 (33%). Vessels with FFR>0.80 presented higher IMR [adjusted mean 27.6 (95% CI: 23.4 to 31.8)] than those with FFR≤0.80 [17.3 (95% CI: 13.0 to 21.7), p=0.001]. Atherosclerotic burden was inversely correlated with CFR (r=-0.207, p=0.055), and in vessels with FFR>0.80 and CFR<2 (n=28, 39%), IMR had a wide dispersion (7-72.7 U), suggesting a combination of DAN and MCD. Vessels with FFR<0.80 and normal CFR presented the lowest IMR, suggesting a preserved microcirculation.
Conclusions—A substantial number of vessels with stenoses showing an FFR>0.80 present disturbed haemodynamics. Integration of FFR, CFR and IMR supports the existence of differentiated patterns of IHD that combine focal and diffuse narrowings with variable degrees of MCD.
- Received January 16, 2013.
- Revision received August 3, 2013.
- Accepted August 30, 2013.