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Absence of significant postdefibrillation bradyarrhythmias in patients with automatic implantable defibrillators
1Natalie and Norman Soref and Family Electrophysiology Laboratory, Wisconsin-Milwaukee.
Insights
Significant postdefibrillation bradyarrhythmias after automatic cardioverter defibrillator implantation are uncommon. Factors like resting heart rate and bypass surgery influence outcomes, but prediction remains challenging.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Devices
Background:
- Postdefibrillation bradycardia and asystole are clinical concerns in patients with implanted automatic cardioverter defibrillators (ICDs).
- Understanding factors influencing cardiac rhythm post-defibrillation is crucial for patient management.
Purpose of the Study:
- To analyze the cardiac rhythm immediately after intraoperative defibrillations during ICD implantation.
- To identify factors influencing postdefibrillation heart rate and asystole duration.
Main Methods:
- Analysis of cardiac rhythm following 157 intraoperative defibrillations in 50 patients undergoing ICD implantation.
- Correlation of postdefibrillation heart rate and asystole duration with various clinical and procedural factors.
Main Results:
- Postdefibrillation heart rate and asystole duration did not correlate with age, conduction abnormalities, arrhythmia type/duration, energy, lead system, or ejection fraction.
- These parameters correlated with resting preoperative heart rate and concurrent coronary artery bypass surgery.
- Temporary pacing was needed in only two patients, both of whom had undergone bypass surgery.
- Amiodarone use was associated with slower heart rates but not longer asystole duration.
- Significant postdefibrillation bradyarrhythmias were uncommon during follow-up, with no symptomatic events reported.
Conclusions:
- Significant bradyarrhythmias after defibrillation are uncommon following ICD implantation.
- Resting heart rate and concurrent bypass surgery are associated with postdefibrillation rhythm, but prediction of risk remains difficult based on clinical factors alone.
Abstract:
Because postdefibrillation bradycardia or asystole is of clinical concern in patients with implanted automatic cardioverter defibrillators, we analyzed the cardiac rhythm after 157 intraoperative defibrillations in 50 patients undergoing implantation of the device. Factors that could influence the heart rhythm immediately after defibrillation were also analyzed. The postdefibrillation heart rate and the duration of postdefibrillation asystole did not correlate with age, conduction abnormalities, type or duration of arrhythmia before defibrillation, delivered energy, lead system, or left ventricular ejection fraction, but they did correlate with the resting preoperative heart rate and the concomitant performance of coronary artery bypass surgery at the time of defibrillator implantation. Temporary pacing (for prolonged asystole) was required in only two patients, both of whom had also undergone bypass surgery. Fourteen patients being treated with amiodarone had slower resting and postdefibrillation heart rates, but the mean duration of posdefibrillation asystole was similar to that seen in patients not receiving any antiarrhythmic medication. On follow-up, 25 monitored and 178 unmonitored automatic defibrillator discharges occurred in 24 patients, without evidence of symptomatic postdefibrillation bradyarrhythmias. Thus significant postdefibrillation bradyarrhythmias were uncommon, but when such a propensity existed it could not be predicted reliably on clinical grounds alone.