July 24, 2007 (Insidermedicine) The risk of sudden death in high-risk patients with hypertrophic cardiomyopathy may be reduced with an implantable cardioverter-defibrillator, according to research published in the Journal of the American Medical Association.

Hypertrophic cardiomyopathy – or HCM – is the most common cause of sudden cardiac death in young people, including trained athletes. The genetic disorder, in which the heart muscle thickens abnormally, affects an estimated 200,000 Americans. The thickened heart muscle can interfere with the heart’s electrical system, increasing the risk for life-threatening abnormal heartbeats and sudden death. 

In the last few years implantable cardioverter defibrillators – or ICDs – have been used as a potentially life-saving treatment in high-risk patients with HCM. An ICD is a device designed to quickly detect a life-threatening, abnormal heart rhythm, and to attempt to convert the rhythm back to normal by delivering an electric shock to the heart. The effectiveness and appropriate selection criteria for this therapy are still unclear.

Researchers analyzed data from more than 500 high-risk patients with HCM who had received an ICD over a 17-year period. 

They found that the device deployed in 20% of patients at some time to prevent a potentially fatal heart rhythm. Those who had a previous episode of cardiac arrest were three times more likely to have deployment of an impulse as compared to those who had the device implanted for having risk factors for cardiac arrest, but never actually had one. An appropriate intervention was likely to occur in people with one, two, or three or more risk factors.

The study shows the effectiveness and reliability of the ICD in preventing sudden death in high-risk patients with HCM. However, the decision to implant an ICD in a patient, especially one with a single risk factor, must include a thorough discussion of the risks and benefits of ICD therapy, and the individual patient’s comfort level living with the device.

Reporting for Insidermedicine, I’m Dr. Susan Sharma.