Amsterdam, the Netherlands - Examining relatives of sudden unexplained death (SUD) victims can help pinpoint the cause of death and identify large numbers of other family members at risk, a new study indicates [1]. Dr Hanno L Tan (University of Amsterdam, the Netherlands) and colleagues investigated 43 families of younger adults who had died suddenly and managed to identify 151 carriers of presymptomatic diseases.

"Examination of surviving relatives of SUD victims not only bears direct clinical significance (timely treatment of presymptomatic disease carriers) but also may serve as a model to shape future improvements in clinical practice at large," the authors write. Their findings are published online July 5, 2005 in Circulation.

The authors point out that 60% to 75% of sudden deaths are caused by potentially inherited diseases, yet postmortem studies either are not conducted or do not provide a diagnosis. By testing living relatives of SUD victims using ECG and Doppler echocardiography, Tan et al hoped to be able to analyze the "diagnostic yield" of examining surviving relatives, as well as identify people who might be at risk of sudden death.

The authors report that they found inherited diseases (and the likely cause of death of the SUD victim) in 17 of the 43 families studied (40%). In an additional four families, no specific diagnosis was established, but Tan et al point out that an unknown underlying inherited disease was likely present because at least two first-degree relatives of the subject had also died at age 40 or younger.

The most common diagnoses in the 17 families were primary electrical diseases, including catecholaminergic polymorphic ventricular tachycardia (CPVT), long-QT syndrome, and Brugada syndrome. Arrhythmogenic right ventricular cardiomyopathy (ARVC), hypertrophic cardiomyopathy, and familial hypercholesterolemia were also found. In all, 47 of 102 surviving family members were found to carry a heritable potential cause of SUD.

The authors then tested an additional 150 living family members of the 47 first identified as having a heritable disease, ultimately identifying an additional 104 affected subjects. In total, 151 surviving relatives were found to be at risk of sudden death.

"The high success rates in diagnosing families and unmasking affected surviving relatives clearly indicate that these efforts should be strongly advised," Tan et al conclude. "This is particularly true because most diagnoses in these families involve primary electrical disease. These disorders are not only highly amenable to treatment but also, if treated correctly, are associated with a virtually normal life expectancy, given that structural derangements are absent."