Diabetes mellitus in heart transplant recipients is associated with lower left ventricular strain and left atrial enlargement

Introduction & Purpose Diabetes mellitus is an increasingly common comorbidity in cardiovascular disease and is associated with adverse cardiovascular outcomes. Diabetes-related heart failure is characterized by left ventricular (LV) stiffness, impaired filling and left atrial enlargement. In patients after heart transplantation, diabetes is related to higher rates of complications and hopitalization. However, the impact of diabetes on myocardial diastolic function following heart transplantation is poorly understood. Here, we evaluate the association between diabetes mellitus and LV diastolic function after heart transplantation. Methods 98 heart transplant recipients with or without diabetes mellitus were enrolled in an ongoing single-center, prospective, observational trial and underwent repeated cardiac magnetic resonance imaging for two years after transplantation between 2016 and 2024. Performing advanced cardiac magnetic resonance including feature-tracking, we analyzed LV global longitudinal and circumferential strain (GLS, GCS), LV early diastolic longitudinal and circumferential strain rate (GLSRe, GCSRe) and left atrial volume index (LAVI) one and two years after heart transplantation. Diabetes mellitus, including both type 1 and type 2, was diagnosed by medical history and/or HbA1c ≥6,5%. Results 29 out of 98 participants (29.5%) had diabetes mellitus (7 out of 29 (24%) had type 1 diabetes mellitus). Compared to non-diabetic participants, diabetic participants had lower GLS (mean±standard deviation: -14.7±2.9% vs. -15.9±2.4%, p=0.04) and higher LAVI (49.9±16.3ml/m² vs. 42.2±12.9ml/m², p=0.01) after one year. There were no significant differences in GCS (-16.5±4.6% vs. -17.8±3.2%, p=0.14), GLSRe (0.87±0.27/s vs. 0.95±0.26/s, p=0.21), and GCSRe (1.05±0.27/s vs. 1.13±0.39/s, p=0.37). Two years after transplantation, they showed significantly lower GLS (-14.9±2.1% vs. -16.8±2.1%, p=0.006), GCS (-17.0±3.1% vs. -18.9±2.7%, p=0.04), GLSRe (0.79±0.23/s vs. 1.01±0.26/s, p=0.01), and GCSRe (1.06±0.21/s vs. 1.27±0.28/s, p=0.02). LAVI was higher in diabetic compared to non-diabetic participants (55.2±20.6ml/m² vs. 38.7±13.7ml/m², p= 0.004). Conclusion(s) In heart transplant recipients, diabetes mellitus was associated with lower left ventricular strain, lower diastolic strain rate, and left atrial enlargement, displaying reduced left ventricular diastolic function, indicating early signs of diabetic cardiomyopathy in the transplanted hearts.