Coronary perivascular fibrosis is associated with impairment of coronary blood flow in patients with non-ischemic heart failure

Abstract Background Although myocardial interstitial fibrosis has been considered to play a pathogenic role in chronic heart failure (HF), the role of perivascular fibrosis, another form of fibrosis, remains to be elucidated. Methods We examined 64 consecutive patients with non-ischemic HF caused by hypertrophic cardiomyopathy (HCM, n  = 16), hypertensive heart disease (HHD, n  = 11), or dilated cardiomyopathy (DCM, n  = 37), diagnosed by both cardiac catheterization and endomyocardial biopsy (right ventricular side of the interventricular septum) in the Tohoku University Hospital between January 2001 and April 2009. We calculated the collagen volume fraction (CVF) and perivascular fibrosis ratio (PFR) in biopsy samples and also examined Thrombolysis in Myocardial Infarction (TIMI) frame count to evaluate coronary blood flow. Results There was no significant correlation between CVF and PFR ( r 2  = 0.0007). Although CVF was comparable among HCM, HHD, and DCM (1.11 ± 1.04, 1.89 ± 1.61, and 1.41 ± 1.48, respectively), PFR was significantly higher in HCM than in DCM (1.78 ± 1.09 vs. 1.23 ± 0.44, p r 2  = 0.3351, p Conclusions These results indicate that coronary perivascular fibrosis is associated with the impairment of coronary blood flow although not associated with interstitial fibrosis or cardiac function, suggesting that it can be a new therapeutic target to improve coronary microcirculation.