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Clinical and functional correlates of early microvascular dysfunction after heart transplantation
François Haddad1, Prateeti Khazanie, Tobias Deuse
1Department of Medicine, Stanford University, Stanford, CA, USA. fhaddad@stanford.edu
Insights
Early microvascular dysfunction in heart transplant recipients is linked to acute rejection and smaller donor hearts. This condition predicts worse graft function and poorer long-term clinical outcomes.
Area of Science:
- Cardiology
- Transplantation Medicine
- Vascular Biology
Background:
- Microvascular dysfunction is an emerging predictor of outcomes in heart transplant recipients.
- Determinants and consequences of early microvascular dysfunction remain incompletely understood.
- This study aimed to identify risk factors and functional correlates of early microvascular dysfunction post-heart transplant.
Purpose of the Study:
- To determine risk factors for early microvascular dysfunction in heart transplant recipients.
- To identify functional correlates of early microvascular dysfunction.
- To assess the association between early microvascular dysfunction and long-term clinical outcomes.
Main Methods:
- Coronary physiology assessment, right heart catheterization, and echocardiography were performed at the first annual evaluation in 63 heart transplant recipients.
- Microvascular dysfunction was assessed using the index of microcirculatory resistance (IMR).
- Presence of microvascular dysfunction was defined as IMR > 20.
Main Results:
- Microvascular dysfunction was present in 46% of patients at 1 year post-transplant.
- A history of acute rejection (OR 4.0) and undersized donor hearts (OR 3.6) were significant risk factors.
- Patients with microvascular dysfunction exhibited lower cardiac index and impaired graft function (MPIs), and faced a higher likelihood of death, graft failure, or allograft vasculopathy at 5 years (HR 2.52).
Conclusions:
- Acute rejection and smaller donor hearts are identified as key risk factors for early microvascular dysfunction.
- Early microvascular dysfunction, assessed by IMR at 1 year, is associated with reduced graft function.
- This dysfunction may predict worse long-term clinical outcomes in heart transplant recipients.
Background:
Microvascular dysfunction is emerging as a strong predictor of outcome in heart transplant recipients. At this time, the determinants and consequences of early microvascular dysfunction are not well established. The objective of the study was to determine the risk factors and functional correlates associated with early microvascular dysfunction in heart transplant recipients.
Methods And Results:
Sixty-three heart transplant recipients who had coronary physiology assessment, right heart catheterization, and echocardiography performed at the time of their first annual evaluation were included in the study. Microvascular dysfunction was assessed using the recently described index of microcirculatory resistance. The presence of microvascular dysfunction, predefined by an index of microcirculatory resistance >20, was observed in 46% of patients at 1 year. A history of acute rejection and undersized donor hearts were associated with microvascular dysfunction at 1 year, with odds ratio of 4.0 (1.3-12.8) and 3.6 (1.2-11.1), respectively. Patients with microvascular dysfunction had lower cardiac index (3.1±0.7 versus 3.5±0.7 L/min per m(2); P=0.02) and mild graft dysfunction measured by echocardiography-derived left and right myocardial performance indices ([0.54±0.09 versus 0.43±0.09; P<0.01] and [0.47±0.14 versus 0.32±0.05; P<0.01], respectively). Microvascular dysfunction was also associated with a higher likelihood of death, graft failure, or allograft vasculopathy at 5 years after transplant (hazard ratio, 2.52 [95% CI, 1.04-5.91]).
Conclusions:
A history of acute rejection during the first year and smaller donor hearts were identified as risk factors for early microvascular dysfunction. Microvascular dysfunction assessed using index of microcirculatory resistances at 1 year was also associated with worse graft function and possibly worse clinical outcomes.
