Invasive Coronary Physiology Assessment for Detecting Microcirculatory Dysfunction in Heart Transplant Recipients

BACKGROUND Coronary vasculopathy is one of the most serious late complications after heart transplantation (Htx). The aim of this study was to assess the utility and safety of the invasive assessment of coronary physiology and investigate the occurrence of coronary microvascular dysfunction (CMD) and its association with clinical characteristics of recipients and donors. MATERIAL AND METHODS Coronary microcirculation was assessed during routine coronary angiography, performed prospectively between December 1, 2020, and July 24, 2023, by using index of microcirculatory resistance (IMR) and coronary flow reserve (CFR). Values of IMR ³25 or CFR <2.0 confirmed CMD. RESULTS Thirty-three patients aged 49±14 years were included; 21 (64%) were men. CMD was found in 8 (24%) patients. There were no complications, and examination was performed in all patients. The median values for IMR and CFR were 13 [IQR: 10-20] and 3.6 [IQR: 2.2-4.9], respectively. CMD was more common in younger patients: 40±16 vs 51±13 years (P=0.045), and those with lower BMI: 22±4 vs 26±4 kg/m² (P=0.016). Patients with CMD were more likely to require pacemaker implantation, with 3 (38%) vs 1 (4%) in the post-transplant period (P=0.012). The median time since Htx was 2 [IQR: 2-10] years and was higher in the CMD group: 9.5 [IQR: 6-16] vs 2 [IQR: 1-8] years, (P=0.042). There were no significant differences in other recipient and donor characteristics. CONCLUSIONS Invasive assessment of coronary physiology was safe and effective and diagnosed CMD in nearly one-fourth of heart transplant recipients. CMD is related to age, time since transplantation, and chronotropic graft dysfunction.