Correspondence
Home Automated Defibrillators after Myocardial Infarction
N Engl J Med 2008; 359:533-535July 31, 2008
- Article
To the Editor:
In the Home Automated External Defibrillator Trial (HAT) (April 24 issue),1 Bardy et al. recruited patients who had had a previous myocardial infarction and who were not eligible for an implantable cardioverter–defibrillator (ICD),2 at a median interval of 1.7 years after myocardial infarction. It has been demonstrated that the absolute risk of a fatal arrhythmic event after myocardial infarction is greatest within the weeks immediately after the event and declines significantly thereafter, reaching a steady state at approximately 1 year.3 In the study by Hohnloser et al.,4 prophylactic ICD therapy during the immediate period after myocardial infarction in patients with a reduced ejection fraction was associated with a significant reduction in deaths from arrhythmia, but such therapy did not add a significant benefit in terms of overall mortality. Consequently, current guidelines do not recommend ICD implantation within the first 40 days after myocardial infarction in patients with a low ejection fraction who are at high risk for sudden death from cardiac causes.2 The potential efficacy of an automated external defibrillator (AED) in such patients during the transitory period after myocardial infarction would be of interest.
4 ReferencesEloi Marijon, M.D.
Hôpital Européen Georges Pompidou, 75908 Paris, France
eloi_marijon@yahoo.fr Nicolas Combes, M.D.
Serge Boveda, M.D.
Clinique Pasteur, 31076 Toulouse, France1
Bardy GH ,Lee KL ,Mark DB , et al. Home use of automated external defibrillators for sudden cardiac arrest. N Engl J Med 2008;358:1793-1804
Full Text | Web of Science | Medline2
Zipes DP ,Camm AJ ,Borggrefe M , et al. ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: a report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for Management of Patients with Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society. Circulation 2006;114:e385-e484
CrossRef | Medline3
Solomon SD ,Zelenkofske S ,McMurray JJV , et al. Sudden death in patients with myocardial infarction and left ventricular dysfunction, heart failure, or both. N Engl J Med 2005;352:2581-2588[Erratum, N Engl J Med 2005;353:744.]
Full Text | Web of Science | Medline4
Hohnloser SH ,Kuck KH ,Dorian P , et al. Prophylactic use of an implantable cardioverter-defibrillator after acute myocardial infarction. N Engl J Med 2004;351:2481-2488
Full Text | Web of Science | Medline
To the Editor:
In their study on the home use of AEDs, Bardy et al. did not consider the possible effect on outcome of the distance a patient lived from a hospital or urgent care facility. For patients assigned to the “control response” (i.e., calling emergency medical services and performing cardiopulmonary resuscitation), the outcome would have depended very much on the time it would take for an ambulance to reach the patient. I work in a remote rural area where emergency response times are considerable, making a successful outcome from syncope due to a ventricular fibrillation arrest highly unlikely. The inclusion of the geography of the area in the assessment of a patient for a home AED might define a subgroup of patients who would benefit from this lifesaving intervention.
Angus M. Ross, M.B., B.S.
Upper Eden Medical Practice, Kirkby Stephen CA17 4RB, United Kingdom
splangus@aol.com Author/Editor Response
Marijon and colleagues raise the possibility of the use of an AED in the immediate period after myocardial infarction. In our trial, AEDs were used in patients who had left the hospital and whose condition was stable. For most patients in our trial, the infarction had occurred at least 1 year earlier. Thus, we have no data on the efficacy of AEDs in preventing death in the immediate period after myocardial infarction. Moreover, the infrequent episodes of sudden cardiac arrest in our study did not allow us to assess the efficacy of AED therapy over and above that of simple resuscitation measures. Consequently, we can neither support nor refute the proposal of the correspondents.
ICDs have not proved to be successful during the period immediately after myocardial infarction, but there may be reasons for this finding other than the defibrillation capability. In the study by Hohnloser et al.,1 the patients who received an ICD had a rate of death from arrhythmia lower than that of patients who did not receive an ICD, but this finding was offset by a higher rate of death from causes other than arrhythmia in the ICD group. These findings suggest that something about the ICD (e.g., pacing or surgery-related complications) countered the value of defibrillation. Moreover, shocks that are delivered early in the period after myocardial infarction in high-risk patients may themselves be detrimental by virtue of their negative inotropic effects, particularly if shocks are inappropriately given for atrial fibrillation. Thus, all the unwelcome consequences of ICD therapy support the potential role of AED therapy in this particular circumstance. AEDs do not pace, create surgical complications, or shock rhythms that are neither ventricular tachycardia nor ventricular fibrillation. Consequently, we believe the question of the value of AEDs in the immediate period after myocardial infarction remains open and deserves further study. Certainly, this is a low-cost therapy that has little risk in its implementation. There is nothing in the results of our study that would argue against such a trial.
Dr. Ross raises the very valuable point that patients with cardiac arrest who are far from emergency medical services may be at elevated risk, as compared with those living in a city. As such, the availability of an AED in the home might have particular value for a patient living in a rural area or in an area where emergency services are suboptimal. In our study, the number of events was too low to address this question in a definitive manner, but we can say that the rescue of patients with cardiac arrest by spouses certainly did occur in rural settings and far from medical aid. It is unlikely these patients would have survived ventricular fibrillation without an AED.
1 ReferencesGust H. Bardy, M.D.
Seattle Institute for Cardiac Research, Seattle, WA 98103-4819
gbardy@sicr.org Kerry L. Lee, Ph.D.
Duke University, Durham, NC 27705Jeanne E. Poole, M.D.
University of Washington, Seattle, WA 981951
Hohnloser SH ,Kuck KH ,Dorian P , et al. Prophylactic use of an implantable cardioverter-defibrillator after acute myocardial infarction. N Engl J Med 2004;351:2481-2488
Full Text | Web of Science | Medline
- Citing Articles (1)
Citing Articles
1
Demetris Yannopoulos, Kostantinos Kotsifas, Keith G. Lurie. (2011) Advances in Cardiopulmonary Resuscitation. Heart Failure Clinics 7:2, 251-268
CrossRef
