Differences in outcomes between patients treated with single- versus dual-chamber implantable cardioverter defibrillators: a substudy of the Multicenter Automatic Defibrillator Implantation Trial II
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Published on: February 28, 2012
Loren D Berenbom1, Brian C Weiford, James L Vacek
1Mid-America Cardiology and the Department of Internal Medicine, Division of Cardiology, University of Kansas Hospital, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA. ldberenbom@mac.md
Insights
Dual-chamber implantable cardioverter defibrillators (ICDs) showed a trend toward higher heart failure and mortality rates compared to single-chamber ICDs in MADIT-II trial patients. Further research is needed to confirm these findings.
Area of Science:
- Cardiology
- Medical Devices
- Clinical Trials
Background:
- Implantable cardioverter defibrillator (ICD) therapy in MADIT-II patients with prior myocardial infarction and low ejection fraction reduced mortality by 31%.
- An unexpected increase in heart failure hospitalizations was observed in the ICD group.
Purpose of the Study:
- To evaluate the influence of single-chamber versus dual-chamber ICDs on heart failure, mortality, and appropriate/inappropriate ICD therapy.
- To analyze outcomes in the Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II) based on ICD generator type.
Main Methods:
- Retrospective analysis of 717 patients randomized to single-chamber ICDs (S-ICDs) or dual-chamber ICDs (D-ICDs) in MADIT-II.
- Endpoints included all-cause mortality, heart failure hospitalizations, and appropriate/inappropriate ICD therapies.
Main Results:
- 404 S-ICDs and 313 D-ICDs were implanted.
- Patients receiving D-ICDs had higher baseline risk factors.
- No statistically significant differences in heart failure or mortality were found between S-ICD and D-ICD groups, despite a trend toward adverse outcomes in the D-ICD group.
Conclusions:
- Dual-chamber ICDs showed a nonsignificant trend toward higher mortality and heart failure rates compared to single-chamber ICDs.
- These findings suggest potential differences in outcomes based on ICD generator choice, warranting further investigation.
Objectives:
We sought to evaluate the influence of single- versus dual-chamber implantable cardioverter defibrillators (ICDs) on the occurrence of heart failure and mortality as well as appropriate and inappropriate ICD therapy in the Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II).
Background:
In MADIT-II, ICD therapy in patients with a prior myocardial infarction and ejection fraction < or =0.30 was associated with a 31% reduction in risk of mortality when compared to conventionally treated patients. An unexpected finding was an increased occurrence of hospitalization for heart failure in the ICD group.
Methods:
Data from 717 patients randomized to ICD therapy with single- or dual-chamber pacing devices in MADIT-II were retrospectively analyzed. Endpoints selected for analysis included death from any cause, new or worsening heart failure requiring hospitalization, death or heart failure, appropriate therapy for ventricular tachycardia (VT) or ventricular fibrillation (VF), and inappropriate ICD therapy for atrial fibrillation or supraventricular tachycardia.
Results:
A total of 404 single-chamber ICDs (S-ICDs) and 313 dual-chamber ICDs (D-ICDs) were implanted. Patients receiving D-ICDs were at a higher risk at baseline than those receiving S-ICDs, with older age, higher NYHA class, more frequent prior CABG, wider QRS complex, more LBBB, higher BUN level, a history of more atrial arrhythmias requiring treatment, and a longer time interval from their index myocardial infarction to enrollment. While there was a trend toward an increase in adverse outcomes in the D-ICD group, no statistically significant differences in heart failure or mortality were observed between S-ICD versus D-ICD groups.
Conclusions:
Patients with D-ICDs had a nonsignificant trend toward higher mortality and heart failure rates than patients with S-ICDs.
