Microvascular Remodeling on Endomyocardial Biopsy and Coronary Flow Reserve by Transthoracic Doppler Echocardiography in Heart Transplant Patients: A Clinical-Pathological Study

Abstract

Purpose Cardiac allograft vasculopathy (CAV) is the main limiting factor of long-term survival after heart transplantation (HT). CAV affects both epicardial coronary vessels and microvasculature. Coronary flow reserve (CFR) by transthoracic Doppler echocardiography (TDE) is an independent predictor of death in HT patients. The aim of the study was to correlate the microvascular remodeling, as assessed by endomyocardial biopsy (EMB), with CFR by TDE in HT patients with normal coronary angiograms. Methods and Materials We studied 28 consecutive HT patients without angiographic CAV (25 male, aged 54±10 years at HT, time from HT 7.5±5 years). Coronary flow velocity in the left anterior descending coronary artery was detected by TDE at rest and during adenosine infusion. CFR was the ratio of hyperaemic diastolic flow velocity (DFV) to resting DFV. A CFR≤2.5 was considered abnormal. In the 1 st year post-HT EMBs, myocytes diameter, fibrosis percentage, capillary density and microvascular remodeling (vessel media area/total vessel area ratio (%)) were evaluated by digital morphometry. Results Microvascular remodeling was higher in patients with CFR≤2.5 (39.2% 11/28 pts) compared with patients with CFR>2.5 (72.3±8 vs 65.2±4.7 %, p Conclusions Our results suggest that coronary microvascular remodeling at EMBs may be the main predictor of abnormal CFR in HT patients. CFR by TDE may be a useful noninvasive tool in the evaluation of microvascular dysfunction/damage in HT. Further studies are warranted.