Diagnostic yield in families to sudden cardiac death victims: a 10-year follow-up study

Aims Up to 70% of sudden cardiac death (SCD) cases in younger individuals are potentially caused by an inherited heart disease. However, long-term diagnostic yield and risk of cardiac events in SCD relatives remain unclear. This study aimed to determine the 10-year diagnostic yield of inherited heart diseases and frequency of cardiac events in SCD relatives. Methods and results This retrospective study included SCD probands and their relatives referred to the Unit for Inherited Heart Diseases at Rigshospitalet, Denmark, from 2005 to 2018. Relatives underwent guideline-recommended screening and follow-up. Diagnoses and cardiac events, such as new-onset reduced left ventricular ejection fraction <= 45%, sustained ventricular tachycardia, appropriate implantable cardioverter-defibrillator therapy, cardiac death, and (aborted) SCD, were registered. A total of 686 relatives (47% males, median baseline age 35 years) to 299 probands (75% males, median death age 41 years) were followed for a median of 10.6 years. At 10-year follow-up, 12% of relatives (n = 82) were diagnosed with an inherited heart disease, with 93% (n = 76) diagnosed within 5 years. Cardiac events occurred in 18 (3%) and 24 (4%) relatives after 5- and 10-year follow-up, respectively. Five (0.7%) relatives of probands with no established diagnosis, who had no diagnosis nor cardiac event within 5 years of follow-up, were diagnosed between >5 and 10 years of follow-up. Conclusion Long-term follow-up identified an inherited heart disease in 12% of SCD relatives, primarily diagnosed within 5 years. Cardiac events were rare (4%). These findings suggest that follow-up may be considered limited to 5 years for specific adult SCD relatives.