Abstract 4146105: Diagnostic Yield in Relatives to Sudden Cardiac Death Patients – A 10-year Follow-Up Study

Introduction: International guidelines recommend cardiogenetic screening of relatives to sudden cardiac death (SCD) patients suspected of having an inherited cardiac disease. However, little is known about the long-term diagnostic yield and risk of cardiac events among relatives. This information is crucial for designing appropriate follow-up strategies for relatives. Aims: To determine the 10-year diagnostic yield and frequency of clinical outcomes in referred families to patients with all cause-SCD. Methods: In this retrospective single-center study, we included consecutively referred families to patients with all cause-SCD from 1 January 2005 until 1 October 2018. Upon referral, the cause of death in the SCD proband was assessed through autopsy reports, genetic testing, and premortem medical records. First-degree relatives were screened following a standard protocol, and diagnostic yields were assessed after five and 10 years of follow-up. Furthermore, cardiac events (i.e. death due to cardiac cause, SCD, aborted SCD, sustained ventricular tachycardia, appropriate implantable cardioverter defibrillator therapy) and relevant clinical outcomes in relatives were monitored. Results: A total of 686 relatives (304 families) were included, and mean age at follow-up was 45 years (47% males). The relatives were followed for a mean of 10.9 years during which 22 patients were lost to follow up. Screening over five years led to 73 relatives (49 families) being diagnosed, resulting in a diagnostic yield of 11%. After 10-years of follow-up, 82 relatives (56 families) were diagnosed, increasing the overall diagnostic yield to 12% with arrhythmogenic right ventricular cardiomyopathy being the most prevalent diagnosis. A total of 11 relatives experienced a cardiac event during follow-up, of whom 10 had a definite diagnosis. Conclusion: Over 10 years of follow-up, 82 (12%) relatives to patients with all cause-SCD were diagnosed with an inherited cardiac disease, primarily within the first five years. The majority of relatives who experienced a cardiac event during follow-up had a definite diagnosis. This underscores the importance of early detection and management of inherited cardiac diseases in the screening of SCD relatives.