Genetic profile and prognosis of non-ischemic dilated cardiomyopathies in afro-caribeans

Abstract Non-ischemic dilated cardiomyopathies are a primary myocardial disease with heterogeneous expression. In 30 to 50% of cases, these cardiomyopathies have a genetic origin, and their global prevalence is estimated at 1/250. Few epidemiological data specific to the Afro-Caribbean population are available. However, the unique demographic characteristics of French overseas territories provide a distinctive environment for studying this pathology, especially from a genetic perspective. The objective of our study was to describe the prevalence and genetic profile of non-ischemic dilated cardiomyopathies. We also aimed to describe their phenotypic characteristics and their prognosis according to mutation status. This is a retrospective descriptive study conducted between January 1st, 2020, and August 31st, 2024, on a cohort of adult patients diagnosed with dilated cardiomyopathy and referred to the cardio-genetics consultation. Data were collected from patient consultation and hospitalization reports. They have included demographic, paraclinical (initial echocardiography, MRI, and ECG results) and prognosis outcomes. We also gathered the genetic results of tested patients, based on the analysis of a predefined panel of 80 genes. Statistical analyses were performed to compare these data according to mutational status. We have included 69 patients and 45 underwent genetic testing. Mean age at diagnosis was 52 years old and we had a majority of men (72%). Among the patients who did the genetic testing, 22 had positive results (49%). The mutations primarily involved the TTN gene (35%) and MYH7 gene (27%). Nearly all patients were of Afro-Caribbean descent, and their clinical and paraclinical characteristics were comparable to contemporary studies, except for cardiovascular risk factors, which followed a specific distribution in the French West Indies, with higher rates of diabetes and hypertension. We also found a significantly higher mortality rate (deaths: 4 vs. 0, p = 0.049) and increased right ventricular involvement (RVEDVi on MRI at 101 ± 39 vs. 75 ± 13 mL/m2, p = 0.047) in mutation carriers. This is the first study in the French West Indies dedicated to the description of the patients carrying non-ischemic dilated cardiomyopathy. Nearly half of our cohort have a genetic mutation, and the majority of variants were identified in the TTN and MYH7 genes. Our results are likely underestimated due to the presumed existence of private mutations specific to this population that are not detected by standard genetic tests. Furthermore, the mutated forms appear to be associated with a poorer prognosis. These findings confirm the importance of genetic screening in the management of dilated cardiomyopathies, in order to improve patient’s morbi-mortality but also to optimize the screening and the management of at-risk relatives.