Do genes play a role in cardiac death susceptibility? Yes, says an international team of researchers that discovered a genetic variation that may be putting people at higher risk of sudden cardiac death (SCD). The study is funded in part by an EU Seventh Framework Programme (FP7) grant. Published in the journal PLoS Genetics, the findings could help shed light on the genetic contribution of SCD susceptibility and offer key targets for functional studies to probe the aetiology and pathogenesis of SCD.
Researchers say SCD is still one of the leading causes of mortality across the globe, with up to 5 million patients dying each year. Despite former, smaller studies finding some genes with a potential link to sudden cardiac arrest, this latest study is the most extensive to date that allows researchers to apply results to the general population.
'We are at the beginning of unravelling the mystery of what causes sudden cardiac arrest and how to prevent it,' explains Dr Sumeet S. Chugh, associate director of the Cedars-Sinai Heart Institute in the United States and senior author of the study. 'If we wait until someone has a sudden cardiac arrest, it is usually too late for treatment. That is why knowing who is genetically susceptible is so important.'
Sudden cardiac arrest is triggered by defective electrical impulses. Heart attacks (myocardial infarction) are caused by clogged coronary arteries whose job it is to ease blood flow to the heart muscle.
Despite emerging advances in medicine and resuscitation over the years, only 5% of patients who suffer sudden cardiac arrest make it. Experts say an implantable cardioverter defibrillator (ICD) could be placed in the chest or abdomen for people who are at risk for SCD or other heart rhythm abnormalities. This would help identify faulty electrical impulses and offer a shock to restore normal rhythm.
Providing improved genetic predictions of risk will bring researchers one step closer to making accurate predictions of which patients could benefit from costly ICD therapy.
The team from Canada, Finland, the Netherlands and the United States investigated the entire set of human genes in a genome-wide association study. They sought to identify potential links between genetic variations and specific conditions or diseases.
The researchers compared the genetic makeup of 4 402 subjects who had experienced sudden cardiac arrest to the DNA (deoxyribonucleic acid) of 30 000 control subjects who had no history of the disorder.
They found a link between a genetic variation in the BAZ2B gene and an increased risk of sudden cardiac arrest. 'If you have this genetic variation in your DNA, it appears that you may have a two-fold higher likelihood of sudden cardiac arrest,' Dr Chugh says.
An association between other genetic variations that account for EKG (electrocardiogram) abnormalities was investigated, and the researchers successfully identified several that could be used for improving the prediction of sudden cardiac arrest in the community.