ICDs effective in helping to prevent sudden cardiac death in patients with certain heart disorder

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).

Of the 506 patients, 20 percent experienced 1 or more appropriate device interventions, in which the ICD terminated ventricular fibrillation (severely abnormal heart rhythm that results in cardiac arrest) or ventricular tachycardia. Intervention rates were 10.6 percent per year for secondary prevention after cardiac arrest (5-year cumulative probability, 39 percent), and 3.6 percent per year for primary prevention (5-year probability, 17 percent).

Time to first appropriate discharge was up to 10 years, with a 27 percent probability 5 years or more after implantation. For primary prevention, 35 percent of the patients with appropriate ICD interventions had undergone implantation for only a single risk factor; likelihood of appropriate discharge was similar in patients with 1, 2, or 3 or more risk markers.

“The results of this international, multicenter study show the effectiveness and reliability of the ICD in prevention of sudden cardiac death in high-risk patients with HCM,” the authors write. “An important proportion of these device interventions occurred in patients who had undergone prophylactic ICD implantation for a single risk factor. Therefore, a single marker of high-risk status may justify consideration for a primary prevention defibrillator in selected patients with HCM.”

(JAMA. 2007;298(4):405-412. Available pre-embargo to the media at www.jamamedia.org)

Editor’s Note: Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

Editorial: Hypertrophic Cardiomyopathy, Sudden Death, and Implantable Cardiac Defibrillators – How Low the Bar?

In an accompanying editorial, Rick A. Nishimura, M.D., and Steve R. Ommen, M.D., of the Mayo Clinic College of Medicine, Rochester, Minn., comment on the findings of the study by Maron and colleagues.

“Patients who have experienced cardiac arrest or documented sustained ventricular tachycardia definitely should be considered for implantation of an ICD. Patients with 2 or more risk factors likely present a high enough risk to warrant implantation of an ICD. However, the decision to implant an ICD in any patient, especially one with a single risk factor, must include a thorough and earnest discussion of the accuracy of the current risk assessment tools, the risks and benefits of ICD therapy, and the individual patient’s viewpoints on procedures, devices, and death. Such an approach will allow the patient-physician team to arrive at an individualized decision regarding ICD implantation.”

(JAMA. 2007;298(4):452-454. Available pre-embargo to the media at www.jamamedia.org)

Editor’s Note: Please see the article for additional information, including financial disclosures, funding and support, etc.