October 26, 2010
The ‘Silent’ Sudden Death Cardiac Killer
(Ivanhoe Newswire) -- The genetic code of sudden cardiac death has been cracked. Now, people are able to be genetically screened for sudden cardiac death based on genes and family history, even if they've had no symptoms. The patients are recommended to receive internal cardiac defibrillators (ICDs) implanted to shock their heart if it stops beating.
"Our discovery has led to a targeted genetic screening and individualized therapy that is significantly improving survival rates," Dr. Sean Connors was quoted as saying at the Canadian Cardiovascular Congress 2010, co-hosted by the Heart and Stroke Foundation and the Canadian Cardiovascular Society. "It's allowing people with the condition to live normal, longer lives. Individualized genetic therapies like this are the future of medicine."
The excitement among cardiologists concerns a rare genetic condition "“ arrhythmogenic right ventricular cardiomyopathy (ARVC).
The term arrhythmogenic refers to deadly cardiac rhythms that can be triggered by electrical impulses within the heart. Cardiomyopathy is a worsening condition where heart muscle is slowly replaced by scar and fat tissue. The combination of the two is lethal.
"People who are at risk often have no symptoms, so the first time we know they have this disease is when they die," Dr. Connors said.
Using genetics to understand and cure diseases is especially vital in ARVC, where the victim often has no symptoms. 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.
"Our diagnostic testing showed that some members of these families have a specific, genetic, electrocardiogram (ECG) mutation "“ ARVD5," said Dr. Connors. Children of parents who carry the gene have a 50 percent chance of carrying it themselves. It is the second most common cause of sudden cardiac death in young people.
The mutation causes premature sudden cardiac death. In males, 50 percent die by 40 and 80 percent die by 50. For women, five percent die by 40 and 20 percent by 50.
Dr. Connors believes there is nothing to lose with implanting the ICD in asymptomatic patients with the mutation. It increases the survival rates in both men and women.
According to Heart and Stroke Foundation spokesperson Dr. Beth Abramson, there are as many as 40,000 sudden cardiac arrests every year in Canada.
"What's fascinating about this study is that they show that preventive intervention works," Dr. Abramson was quoted as saying. "This treatment is not only prolonging lives; it's giving families peace of mind and hope for the future."
She also notes, "This is exciting information for physicians working with these rare cases but is also important to remember that the most common causes of heart disease relate to lifestyle. It is important that all of us, regardless of family history, take care of our hearts: basic things like smoking cessation, following a healthy diet, and physical activity go a long way in protecting our health."
SOURCE: Cardiovascular Congress 2010, co-hosted by the Heart and Stroke Foundation and the Canadian Cardiovascular Society held in Montreal, Canada on October 23-27, 2010