Fibrotic Myocardial Remodeling in Children and Adolescents after Cardiac Transplantation—A CMR Native T1 Mapping Study

Background: Adverse fibrotic myocardial remodeling has been reported in patients after heart transplantation (HT). The aim of our study was to quantify diffuse myocardial fibrosis using CMR in a cohort of children and adolescents after HT to identify potential underlying factors that are related to increased fibrosis and to assess its hemodynamic relevance.

Method: A total of 105 HT recipients (age 17.9 ± 7.1 years) without any clinical signs of acute rejection were assessed by CMR 11.8 ± 6.8 years after HT. Left ventricular (LV) volumes and mass were derived from short-axis cine images and LV strain/strain rate was assessed using tissue tracking technique. A T1 mapping sequence (MOLLI) was used to quantify native T1 times within the LV myocardium at a midventricular short axis slice. The collagen volume fraction (CVF) was obtained from histological analysis of endomyocardial biopsy samples.

Results: Septal native LV T1 times showed a weak but significant association with CVF (r = 0.36, p = 0.01). T1 times were not related to LV size, mass and ejection fraction but correlated inversely with LV mass-to-volume ratio (r = 0.26, p = 0.001) and systolic (r = 0.32, p = 0.001) and diastolic longitudinal (r=0.25, p = 0.01) strain/strain rate. Neither a history of rejection, organ ischemic time, BSA ratio donor-acceptor, and time since HT were significantly related to T1 times.

Conclusion: Fibrotic myocardial remodeling after HT affects LV systolic and diastolic longitudinal function and is associated with an increased mass-to-volume ratio. Future studies should aim to identify underlying factors and mechanisms that promote the development of fibrotic changes post HT and to assess its prognostic relevance.

Publication History

Article published online:
12 February 2022