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Updated: May 25, 2025
Evaluation of Coronary Flow Reserve After Myocardial Ischemia Reperfusion in Rats
Published on: June 28, 2019
Microvascular Resistance Reserve and Prognosis After Heart Transplantation
Junho Ha1, Seung Hun Lee2, Ki-Hong Choi1
1Division of Cardiology, Department of Medicine, Heart Vascular Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
Background:
Impaired microcirculatory function after heart transplantation is associated with increased risk for acute cellular rejection. Microvascular resistance reserve (MRR) is a novel index for assessing microcirculatory function, irrespective of epicardial coronary artery stenosis, but it has not been validated in transplanted hearts.
Objectives:
The aim of this study was to investigate the prognostic impact of MRR in heart transplantation.
Methods:
The present study prospectively enrolled 154 heart transplant recipients who underwent scheduled coronary angiography and invasive coronary physiological assessment 1 month after transplantation. Coronary microcirculatory dysfunction was defined as MRR ≤3.0. Elevated microcirculatory resistance was defined as an index of microcirculatory resistance ≥15. The presence of epicardial coronary stenosis was assessed by fractional flow reserve. The primary outcome was a composite of death or biopsy-proven acute cellular rejection of grade ≥ 2R after transplantation.
Results:
Among the total patients, 22.1% (34 of 154) had impaired microcirculatory function (MRR ≤3.0), and 77.9% (122 of 154) had preserved microcirculatory function (MRR >3.0). During median follow-up of 730 days (Q1-Q3: 730-730 days), patients with MRR ≤3.0 showed increased risk for a composite of death or acute cellular rejection (adjusted HR: 5.31; 95% CI: 2.65-10.64; P < 0.001), acute cellular rejection (adjusted HR: 4.83; 95% CI: 2.20-10.60; P < 0.001), and death (adjusted HR: 5.19; 95% CI: 1.24-21.62; P = 0.024). MRR was significantly associated with increased risk for death or acute cellular rejection, regardless of epicardial coronary artery stenosis (HR adjusted for fractional flow reserve: 1.89 per 1-U decrease in MRR; 95% CI: 1.46-2.46; P < 0.001) or elevated microcirculatory resistance (HR adjusted for index of microcirculatory resistance: 1.90 per 1-U decrease in MRR; 95% CI: 1.43-2.52; P < 0.001).
Conclusions:
Impaired microcirculatory function, determined by MRR early after heart transplantation, identified patients at high risk for death or acute cellular rejection, regardless of epicardial coronary artery stenosis or elevated microcirculatory resistance. (Physiologic Assessment of Microvascular Function in Heart Transplant Patients; NCT02798731).
