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Cardiology ICDs prevent sudden cardiac death in patients with hypertrophic cardiomyopathy
Cardiology ICDs prevent sudden cardiac death in patients with hypertrophic cardiomyopathy
ICDs prevent sudden cardiac death in patients with hypertrophic cardiomyopathy
Monday, 29 November 1999 19:00 | 
| Specialties - Cardiology |
Implantable cardioverter-defibrillators (ICD) reduce the likelihood of sudden cardiac death in high-risk patients with hypertrophic cardiomyopathy (HCM), according to results of an international, multicenter registry study.
Implantable cardioverter-defibrillators (ICD) reduce the likelihood of sudden cardiac death in high-risk patients with hypertrophic cardiomyopathy (HCM), according to results of an international, multicenter registry study. At times, the results suggest, an ICD is a life-saving measure even for patients with only one risk factor for sudden cardiac arrest.
However, it is only recently that ICDs have been used to treat HCM, lead author Dr. Barry J. Maron and associates note in their article in the Journal of the American Medical Association for July 25. "The effectiveness and appropriate selection of patients for this therapy is incompletely resolved," they add.
Their study included 506 patients with HCM who received an ICD at 42 institutions in the US, Europe, and Australia. Average age was 42, and mean follow-up was 3.7 years.
Risk factors included family history of sudden death, massive left ventricular hypertrophy, nonsustained ventricular tachycardia on Holter monitoring, and unexplained prior syncope.
In 123 of the patients, the devices were placed for secondary prevention after a resuscitated cardiac arrest or sustained ventricular tachycardia. Among this group, 42 per cent experienced appropriate ICD discharges. Intervention rate was 10.6 per cent per year and cumulative probability of discharge at five years was 39 per cent.
Among the other 383 patients who received an ICD for primary prevention, 13 per cent experienced an appropriate ICD discharge. The intervention rate was 3.6 per cent per year, with a cumulative probability of discharge of 17 per cent at five years.
In the group of patients who received appropriate ICD activations, ages ranged from five to 83 years; 40 per cent were below 40 years of age, the report indicates. In the subset of patients treated for primary prevention, neither intervention rates per 100 person-years, nor cumulative probability of ICD discharge, was related to the number of patient risk factors.
Evidence that many of the patients who had only one risk factor but still received ICD interventions "appears to contradict the view that two or more risk factors are mandatory to trigger recommendations for primary prevention ICDs," Dr. Maron and his team state.
Nonetheless, they emphasize, they do not advocate a strategy of universal ICD implantation in all patients with HCM who have only one risk factor.
In a related editorial, Dr. Rick A. Nishimura and Dr. Steve R. Ommen, from the Mayo Clinic College of Medicine in Rochester, Minnesota, caution that the decision to treat a patient with an ICD, especially a patient with a single risk factor, "is not trivial." New imaging modalities may help identify patients at risk for sudden death, they say.
But in general, the two physicians recommend that "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.
However, it is only recently that ICDs have been used to treat HCM, lead author Dr. Barry J. Maron and associates note in their article in the Journal of the American Medical Association for July 25. "The effectiveness and appropriate selection of patients for this therapy is incompletely resolved," they add.
Their study included 506 patients with HCM who received an ICD at 42 institutions in the US, Europe, and Australia. Average age was 42, and mean follow-up was 3.7 years.
Risk factors included family history of sudden death, massive left ventricular hypertrophy, nonsustained ventricular tachycardia on Holter monitoring, and unexplained prior syncope.
In 123 of the patients, the devices were placed for secondary prevention after a resuscitated cardiac arrest or sustained ventricular tachycardia. Among this group, 42 per cent experienced appropriate ICD discharges. Intervention rate was 10.6 per cent per year and cumulative probability of discharge at five years was 39 per cent.
Among the other 383 patients who received an ICD for primary prevention, 13 per cent experienced an appropriate ICD discharge. The intervention rate was 3.6 per cent per year, with a cumulative probability of discharge of 17 per cent at five years.
In the group of patients who received appropriate ICD activations, ages ranged from five to 83 years; 40 per cent were below 40 years of age, the report indicates. In the subset of patients treated for primary prevention, neither intervention rates per 100 person-years, nor cumulative probability of ICD discharge, was related to the number of patient risk factors.
Evidence that many of the patients who had only one risk factor but still received ICD interventions "appears to contradict the view that two or more risk factors are mandatory to trigger recommendations for primary prevention ICDs," Dr. Maron and his team state.
Nonetheless, they emphasize, they do not advocate a strategy of universal ICD implantation in all patients with HCM who have only one risk factor.
In a related editorial, Dr. Rick A. Nishimura and Dr. Steve R. Ommen, from the Mayo Clinic College of Medicine in Rochester, Minnesota, caution that the decision to treat a patient with an ICD, especially a patient with a single risk factor, "is not trivial." New imaging modalities may help identify patients at risk for sudden death, they say.
But in general, the two physicians recommend that "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.
