High-risk patients with hypertrophic cardiomyopathy appear to have reduced risk of sudden cardiac death with an implantable cardioverter-defibrillator that terminates dangerous heart rhythm disorders, according to a study in the July 25 issue of JAMA: The Journal of the American Medical Association.
Hypertrophic cardiomyopathy (HCM) is the most common cause of sudden cardiac death in young people, including trained athletes. HCM is a genetic disease in which the heart muscle thickens abnormally, which can interfere with the heart's electrical system, increasing the risk for life-threatening abnormal heartbeats (arrhythmias). Only in the last few years has the implantable cardioverter-defibrillator (ICD) been systematically used as a potentially life-saving treatment in high-risk patients with HCM, according to background information in the article. An ICD is a device designed to quickly detect a life-threatening, abnormal heart rhythm, and attempt to convert the rhythm back to normal by delivering an electrical shock to the heart. The effectiveness and appropriate selection of HCM patients for this therapy is not certain.
Barry J. Maron, M.D., of the Minneapolis Heart Institute Foundation, Minneapolis, and colleagues examined the clinical risk profile and incidence and effectiveness of ICD intervention in patients with HCM. The researchers analyzed data from a multicenter registry of ICDs implanted between 1986 and 2003 in 506 patients with HCM, average age 42 years. Patients were judged to be at high risk for sudden death. Average follow-up was 3.7 years.
Risk factors analyzed included history of premature HCM-related sudden death in 1 or more first-degree or other relatives younger than 50 years; massive left ventricular hypertrophy (enlargement); a certain type of nonsustained ventricular tachycardia (abnormally rapid heart rhythm); and prior unexplained syncope (temporary loss of consciousness).