CCC: Identifying gene in sudden death allows preventive ICD therapy

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Researchers in Newfoundland have cracked the genetic code of a sudden death cardiac killer, which allows them to implant defibrillators in asymptomatic patients with the suspect gene and a family history of the arrhythmia, according to their study presented at the 2010 Canadian Cardiovascular Congress (CCC) in Montreal.

"Our discovery has led to a targeted genetic screening and individualized therapy that is significantly improving survival rates," said Sean Connors, MD, at the conference. "It's allowing people with the condition to live normal, longer lives. Individualized genetic therapies like this are the future of medicine."

The research concerns a rare genetic condition called arrhythmogenic right ventricular dysplasia 5 (ARVD5).

"Newfoundlanders likely have the highest incidence in the world of this disease," said Connors, a cardiologist and associate professor of medicine at Memorial University of Newfoundland in Newfoundland and Labrador.

He added that the first time it is known that someone has this disease often is when he or she dies from it.

The surest sign that a disease is genetic in origin is when it is manifests itself in family histories, showing up in generation after generation, he said. "Our diagnostic testing showed that some members of these families have a specific, genetic, electrocardiogram mutation—ARVD5."

There is a 50 percent chance that children of those with the condition will also be carriers of the gene. It is considered the second most common cause of sudden cardiac death in young people, he said.

The mutation causes premature sudden cardiac death in males: 50 percent die by age 40 and 80 percent by age 50. For women, the rate is 5 percent and 20 percent, respectively.

Given those figures, Connors and colleagues realized nothing would be lost by implanting ICDs in asymptomatic patients with ARVD5.

Earlier this year, they reviewed the data of the prevention program which they started in 1999. They concluded that ICD treatment for primary prevention in both sexes, and secondary prevention in males significantly improved survival.