Cardiac evaluation of relatives and post-mortem sequencing recommended for young SCD victims
Experts from Hong Kong are recommending cardiac evaluation of surviving relatives and next-generation sequencing (NGS) molecular autopsy as components of forensic investigations for young victims of sudden cardiac death (SCD).
“The two main advantages of molecular autopsy in SCD are that it enables a correct diagnosis of SCD to be established, which can bring some level of closure to the family, and ultimately prevents another tragedy among family members,” the authors of the study explained. [Hong Kong Med J 2019;25:21-29]
The two-part study included a retrospective 5-year review of autopsies performed on young SCD victims, followed by a prospective 2-year study combining conventional autopsy investigations, molecular autopsy, and cardiac evaluation of first-degree relatives of SCD victims.
Among the 289 SCD victims (median age, 32 years; male:female ratio, 9:2) included in the 5-year review, the most common causes of SCD were coronary artery disease (35 percent), followed by unexplained causes (25 percent) and structural heart diseases such as dilated cardiomyopathy (9 percent), myocarditis (6 percent) and aortic dissection (6 percent).
There were 21 SCD victims (median age, 31 years; 86 percent male) identified for the prospective 2-year study. Eighty-five percent showed negative autopsy findings, while 10 percent had arrhythmogenic right ventricular cardiomyopathy (ARVC) and 5 percent had hypertrophic cardiomyopathy (HCM).
The SCD victims died either during resting (48 percent) or sleeping (24 percent), or during exercise (14 percent). A family history of SCD (14 percent) or syncope (33 percent) was documented in a proportion of the victims. Past health was unremarkable in the majority (71 percent) of the SCD victims. Genetic analysis showed that 29 percent were positive for heterozygous genetic variants.
Combining conventional and molecular autopsy findings, 57 percent of the deaths were of unknown cause. ARVC (19 percent), Brugada syndrome (10 percent), HCM (5 percent), long QT syndrome (5 percent) and catecholaminergic polymorphic ventricular tachycardia (5 percent) were confirmed as causes of death among the remaining SCD victims.
“In our study, more than half [55 percent] of the first-degree relatives who underwent genetic testing were found to carry positive genetic variants. We recommend that family pedigree for at least three generations should be included in the extended clinical workup, and genetic counselling should be considered for second- or higher-degree relatives,” the authors emphasized.
Ten percent of the relatives manifested with sudden arrhythmic death syndrome (SADS)−related clinical features. Family screening of one victim showed an electrocardiogram (ECG) of prolonged corrected QT interval in the asymptomatic father and sister. Another victim’s father was found to carry the same mutation (SCN5A) and a type 2 Brugada ECG pattern.
“This is the first local feasibility study incorporating cardiac evaluation of surviving relatives and NGS molecular autopsy into conventional forensic investigations. This approach may be considered to cover SCD victims of all age groups, with other potential applications such as sudden unexpected death in epilepsy, or sudden infant death syndrome. Our study can be considered as an important advance in diagnosing young SCD victims in East Asian populations,” the authors concluded.