Microcirculation and intravascular imaging assessment in heart transplant recipients for detection of cardiac allograft vasculopathy: a pilot study.

Introduction: Cardiac allograft vasculopathy (CAV) is the leading cause of late mortality after heart transplantation (HTx). It is a progressive and diffuse process involving both the epicardial coronary arteries and the microcirculation, caused by immunologic and non-immunologic factors resulting in localized inflammation. Microcirculatory and intravascular imaging assessments help characterize the physiological phenotype of patients and better predict their prognosis.

Aim: To conduct a comprehensive imaging and functional evaluation of the coronary arteries for early detection of vasculopathy in patients after heart transplantation.

Material and methods: This is a prospective, single-center study enrolling patients who underwent heart transplantation and their first coronary angiography (CA) within the first 2 years after HTx. In all patients, intravascular ultrasound was performed to detect thickening of the intima-media complex. Additionally, functional assessment of coronary arteries and microcirculation was done.

Results: Vessels from 10 patients (mean age: 56.6 ±11.6 years) within the first 2 years after transplantation were assessed with additional left anterior descending (LAD) evaluation. A plaque burden of > 30% in the segment of the most significant stenosis in the LAD was observed in 70% of vessels, and thickening of the intima-media complex > 0.5 mm was observed in 60% of cases. Fractional flow reserve (FFR) < 0.8 occurred in 1 patient. The mean index of microcirculatory resistance (IMR) was 17 ±10, and mean coronary flow reserve (CFR) was 4.33 ±1.1.

Conclusions: In heart transplantation patients, comprehensive angiographic, imaging, and physiological evaluation including microcirculation assessment may allow for early detection of allograft vasculopathy.