Cardiac conduction disorders in young adults: clinical characteristics and genetic background of an underestimated population

Background: Cardiac conduction disorders (CCD) in patients <50 years are a rare and mostly unknown condition. Objective: We aimed to assess clinical characteristics and genetic background of patients < 50 years with CCD of unknown origin. Methods: We retrospectively review a consecutive series of patients with a diagnosis of CCD before the age of 50 referred to our Centre between January 2019 and December 2021. Patients underwent complete clinical examination and genetic evaluation. Results: We enrolled 39 patients with a median age of 40 years (28-47 years) at the onset of symptoms. A cardiac implantable device (CIED) was implanted in 69% of the patients. In 15 out of 39 CCD index patients (38%), we found a total of 13 different gene variations (3 pathogenic, 6 likely pathogenic and 4 variants of uncertain significance), occurring mostly in three genes (SCN5A, TRPM4 and LMNA). In our cohort, genetic testing leads to the decision to implant an ICD in two patients for the increased risk of SCD. Conclusions: Patients with the occurrence of CCD before the age of 50 present a high rate of pathologic gene variations, occurring mostly in three genes (SCN5A, TRPM4 and LMNA). The presence of pathogenic variations may add information regarding the prognosis and lead to an individualized therapeutic approach.