Background <p>The tuberous sclerosis complex is an autosomal dominant genetic disorder caused by mutations in the TSC 1 or 2 genes. Cardiac rhabdomyomas are the most frequent initial manifestation and leading cause of mortality in children under 10 years of age. Data on Brazilian patients with rhabdomyomas are scarce.</p> Objectives <p>This study aims to describe the diagnostic aspects and clinical features observed during the follow-up at a high-complexity cardiology centre.</p> Methods <p>This was a retrospective, descriptive, single-centre study, based on medical records. Patients of all age groups and sexes were included, with a confirmed diagnosis of tuberous sclerosis and at least two serial transthoracic echocardiograms performed at the service from January 1997 to January 2024. Patients with uncertain diagnoses and incomplete records were excluded.</p> Results <p>Among the 69 patients evaluated, 42 (60.86%) had cardiac tumours, with 41 rhabdomyomas and one pericardial lipoma, with a mean follow-up time of 6 years. The median age of the cohort at first evaluation was 3.5 years [1.0; 15.8]. Multiple tumours were observed in 75.6% of cases. Most patients with rhabdomyomas were asymptomatic at both evaluations (73.8% and 85.71%, respectively); however, episodes of arrhythmia were recorded in 21.43% of the sample during follow-up. Only one patient presented with ventricular dysfunction, and one patient required surgical treatment, resulting in death. Incomplete involution of the mass occurred in 76.2% of cases, complete regression in 16.7%, and maintenance, increase, or need for surgical treatment in 7.2%.</p> Conclusions <p>Our data indicate a considerable prevalence of arrhythmias and the persistence of identifiable masses throughout follow-up in a Brazilian cohort of patients with tuberous sclerosis complex, emphasizing the clinical relevance of persistent lesions as potential arrhythmogenic substrates requiring long‑term surveillance.</p>