Correspondence
Defibrillator Implantation Early after Myocardial Infarction
N Engl J Med 2010; 362:269-270January 21, 2010
- Article
To the Editor:
Steinbeck et al. (Oct. 8 issue)1 conclude that prophylactic therapy with the use of an implantable cardioverter–defibrillator (ICD) early after a myocardial infarction did not reduce overall mortality among patients with clinical features that placed them at increased risk for death. However, the clinical criteria used for the selection of patients at high risk in this study were not sufficient per se for prophylactic ICD implantation according to current guidelines.2 In fact, prophylactic ICD therapy is indicated for patients with a previous myocardial infarction and a left ventricular ejection fraction of 40% or less only if they are found to have unsustained ventricular tachycardia and inducible ventricular arrhythmias on an electrophysiological study, and the mere presence of unsustained ventricular tachycardia has never been shown to increase the risk of death in this context. Moreover, the fact that there were more patients with diabetes and patients with left bundle-branch block in the ICD group could have influenced the rates of nonsudden cardiac death, since both clinical conditions are associated with worse outcomes after a myocardial infarction.
Therefore, the population sample in the Immediate Risk Stratification Improves Survival (IRIS) trial (ClinicalTrials.gov number, NCT00157768) did not seem to represent the high-risk patients for whom current guidelines recommend the prophylactic implantation of an ICD after a myocardial infarction.
Oscar Cano, M.D.
José Olagüe, M.D.
Hospital Universitario La Fe, Valencia, Spain
oscape13@hotmail.com No potential conflict of interest relevant to this letter was reported.
2 References1
Steinbeck G ,Andresen D ,Seidl K , et al. Defibrillator implantation early after myocardial infarction. N Engl J Med 2009;361:1427-1436
Full Text | Web of Science | Medline2
Epstein AE ,DiMarco JP ,Ellenbogen KA , et al. ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices) developed in collaboration with the American Association for Thoracic Surgery and Society of Thoracic Surgeons. J Am Coll Cardiol 2008;51:e1-e62[Erratum, J Am Coll Cardiol 2009;53:147, 1473.]
CrossRef | Web of Science | Medline
To the Editor:
Sustained ventricular tachycardia and ventricular fibrillation complicate up to 10% of myocardial infarctions.1,2 Nevertheless, Steinbeck et al. found no evidence that insertion of an ICD improved survival among patients with acute myocardial infarction who received optimal medical therapy. There was a significant reduction in the number of sudden cardiac deaths with ICD therapy. However, as with previous trials of aggressive beta-blockade,3 the Achilles' heel of ICD therapy in these patients is an increase in the incidence of nonsudden cardiac death.
The authors suggest that unresolved mechanisms, including “untoward effects of defibrillator shocks and antitachycardia pacing,” may increase rates of nonsudden cardiac death. The current standard of care mandates follow-up evaluation of the device in patients who have undergone implantation of an ICD. To further explore this important possibility, it may be worthwhile to compare the follow-up data on patients who have undergone implantation of an ICD and had nonsudden cardiac death in this trial with patients who did not.
John W. McEvoy, M.B.
Johns Hopkins Hospital, Baltimore, MD
jmcevoy1@jhmi.edu No potential conflict of interest relevant to this letter was reported.
3 References1
Newby KH ,Thompson T ,Stebbins A ,Topol EJ ,Califf RM ,Natalie A . Sustained ventricular arrhythmias in patients receiving thrombolytic therapy: incidence and outcomes. Circulation 1998;98:2567-2573
Web of Science | Medline2
Al-Khatib SM ,Granger CB ,Huang Y , et al. Sustained ventricular arrhythmias among patients with acute coronary syndromes with no ST-segment elevation: incidence, predictors, and outcomes. Circulation 2002;106:309-312
CrossRef | Web of Science | Medline3
Chen ZM ,Pan HC ,Chen YP , et al. Early intravenous then oral metoprolol in 45,852 patients with acute myocardial infarction: randomised placebo-controlled trial. Lancet 2005;366:1622-1632
CrossRef | Web of Science | Medline
Author/Editor Response
In response to Cano and Olagüe: of course the method of risk stratification in our investigator-driven study involving patients in the early phase of acute myocardial infarction, while reasonable, was not covered by current guidelines of ICD implantation. However, risk stratification as applied in the IRIS trial indeed identified patients who were at considerable risk for death; the rate of death from any cause was 22.9% and the rate of sudden death was 11.6% at 3 years in the control group. In each of the subgroups, considerable reductions in rates of sudden cardiac death were observed; these might have translated into a reduced overall mortality if rates of nonsudden cardiac death were not increased. Slight differences in baseline characteristics with respect to diabetes and left bundle-branch block did not affect the results of the IRIS trial in terms of all-cause mortality or specific causes of death. Additional analyses revealed that the results did not change if diabetes and left bundle-branch block were added to the proportional-hazards or proportional-subdistribution-hazard models, either as covariates or as effect modifiers.
As McEvoy suggests, all patients assigned to the ICD group underwent regular follow-up evaluations, and data on more than 5000 follow-up visits during which data collected by the ICD were recorded and saved in a database are currently being analyzed to shed some light on the mechanism or mechanisms underlying the increase in nonsudden cardiac death in the ICD group in the IRIS trial.
Gerhard Steinbeck, M.D.
Ludwig-Maximilians University, Munich, Germany
gerhard.steinbeck@med. uni-muenchen. de Dietrich Andresen, M.D.
Klinikum am Urban, Berlin, GermanyKarl Wegscheider, Ph.D.
University Hospital, Hamburg-Eppendorf, GermanySince publication of their article, the authors report no further potential conflict of interest.
