Pathological Substrates of Impaired Coronary Flow Reserve in Dilated Cardiomyopathy and Heart Transplant Patients

Abstract

Purpose The aim of this study is to evaluate the cause of CFR impairment in DCM patients by correlating functional CFR assessed and microvascular structural abnormalities measured on endomyocardial biopsy (EMB). Methods and Materials We evaluated EMBs from 26 consecutive DCM patients and EMBs from 11 consecutive Heart Transplant patients. We performed morphometric analysis on EMBs. We measured myocyte mean diameter, capillary density, microvascular remodeling (vessel media area/total vessel area ratio (%)). Coronary flow velocity in the left anterior descending coronary artery was detected by Transthoracic Doppler Echocardiography (TDE) at rest and during adenosine infusion. CFR was the ratio of hyperemic diastolic flow velocity (DFV) to resting DFV. A CFR≤2.5 was considered abnormal. The results were compared to a control group, consisted of 11 heart-transplant (HTx) patients with impaired CFR due to microvascular remodeling. Results Despite CFR in DCM patients is comparable to the HTx pts (2,25 ± 0,61 vs. 2,0 ± 0,5, p=0.4), microvascular remodeling is significantly lower in DCM pts compared to HTx group (43,93 ± 7,12% vs. 72,3 ± 8,0%, p Conclusions CFR impairment in DCM patients is not related to microvascular remodeling. It is closely related to cardiac performance and the patient’s clinical status. Patients with pathological CFR (CFR