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Ventricular fibrillation and polymorphic ventricular tachycardia with critical coronary artery stenosis: does bypass
1Electrophysiology Laboratory, Milwaukee Heart Institute of Sinai Samaritan Medical Center, Wisconsin.
Insights
Coronary artery bypass surgery alone does not prevent life-threatening arrhythmias in patients with ventricular fibrillation. Implantable cardioverter-defibrillators (ICDs) significantly improve survival in these high-risk individuals.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Surgery
Background:
- Coronary artery bypass surgery (CABS) was previously thought sufficient to prevent sudden death in critical coronary artery stenosis with ventricular arrhythmias.
- This study examines outcomes in patients with sudden death, ventricular fibrillation (VF), or polymorphic ventricular tachycardia (PVT) who received a defibrillator during bypass surgery.
Purpose of the Study:
- To evaluate the efficacy of implantable cardioverter-defibrillators (ICDs) in preventing recurrent life-threatening arrhythmias and improving survival in patients undergoing bypass surgery for severe coronary artery disease.
- To assess the impact of ICD implantation alongside coronary revascularization on patient survival rates.
Main Methods:
- A cohort of 58 consecutive patients with severe coronary artery disease and a history of sudden death due to VF/PVT underwent defibrillator implantation concurrent with bypass surgery.
- Electrophysiologic studies were performed pre- and post-revascularization. Patient survival was compared using projected survival curves based on defibrillator discharges versus total and cardiac death rates.
- Multivariate analysis identified predictors of defibrillator discharge.
Main Results:
- After a mean follow-up of 4.6 years, 71.2% of patients survived free of total death, with projected survival at 58.8% (P < 0.05).
- 22 patients experienced appropriate ICD shocks (preceded by syncope/presyncope), and 19 had asymptomatic shocks.
- Low ejection fraction (<30%) and inducible arrhythmias with S2/S3 extrastimuli were independent predictors of defibrillator discharge.
Conclusions:
- Coronary artery bypass surgery alone does not adequately protect against recurrent life-threatening arrhythmias like ventricular fibrillation and polymorphic ventricular tachycardia.
- Implantable cardioverter-defibrillator implantation provides a significant survival benefit in patients with severe coronary artery disease experiencing these dangerous arrhythmias.
Introduction:
Previous studies have suggested that coronary artery bypass surgery is sufficient to prevent recurrence of sudden death in patients with critical coronary artery stenosis presenting with ventricular fibrillation or polymorphic ventricular tachycardia. We present our experience in patients with one or more episodes of sudden death associated with documented ventricular fibrillation or polymorphic ventricular tachycardia and severe operable coronary artery disease who underwent defibrillator implant at the time of bypass surgery.
Methods And Results:
Fifty-eight consecutive patients (age 63 +/- 8 years) were included in this study. Eighteen of the 58 patients had no evidence of previous myocardial infarction. The mean ejection fraction was 37 +/- 13%. All patients underwent electrophysiologic study before and after revascularization. At the time of first defibrillator discharge, each patient was reevaluated to exclude the presence of ischemia. The benefits of defibrillator implant were estimated comparing the projected survival based upon defibrillator discharge preceded by syncope or presyncope with survival curves generated including total death and sudden plus cardiac death. After a mean follow-up of 4.6 +/- 2 years, 22 patients received appropriate shocks preceded by syncope or presyncope, and an additional 19 patients received asymptomatic shocks. At 4 years, survival free of total death was 71.2%, and the projected survival was 58.8% (P < 0.05). Multivariate analysis showed that ejection fraction lower than 30% and induction of arrhythmia with one or two extrastimuli (S2, S3) were independent predictors for defibrillator discharge. None of the remaining variables including age, gender, number of bypasses, history of myocardial infarction, and type of arrhythmias induced were predictive for death and occurrence of shocks.
Conclusions:
In patients with ventricular fibrillation and polymorphic ventricular tachycardia, bypass surgery does not protect from recurrence of life-threatening arrhythmias, and, as in our population, defibrillator implant may have significant impact on survival.