ARRHYTHMIAS AFTER CARDIOVERTER-DEFIBRILLATOR IMPLANTATION - COMPARISON OF EPICARDIAL AND TRANSVENOUS SYSTEMS

Surgery for implantable cardioverter-defibrillators can cause postoperative exacerbation of ventricular and atrial arrhythmias. It is not known whether the techniques of electrode implantation (epicardial vs transvenous) influence the incidence of arrhythmia exacerbation. We reviewed the postoperative course of 229 consecutive patients who received either epicardial (n = 119) or transvenous (n = 110) implantations from 1984 to 1994. Exacerbation of ventricular tachycardia (VT) was defined as an increase in the number of sustained VTs during the postoperative versus the preoperative 2 weeks. Of the entire cohort, 18 patients (8%) developed exacerbation of VT after operation, which was more frequent in patients with epicardial than with transvenous implantations (12% vs 4%, p < 0.03, odds ratio 3.5, 95% confidence interval 1.0 to 13.2). New-onset atrial fibrillation occurred in 15% of patients with epicardial versus 1% of those with transvenous implantations (p = 0.00005, odds ratio 19.4, 95% confidence interval 2.7 to 86.7). These differences persisted after excluding patients with concurrent cardiac surgery. Preoperative occurrence of arrhythmias was the strongest independent predictor for postoperative occurrence (p < 0.01 for VT p < 0.0001 for atrial fibrillation). Epicardial implantation (p = 0.03) and a history of myocardial infarction (p = 0.04) were independent predictors for postoperative VT exacerbation, whereas epicardial implantation (p < 0.05) and concurrent coronary bypass surgery (p = 0.0001) were independent predictors for postoperative new atrial fibrillation. Perioperative discontinuation of antiarrhythmic drugs did not influence postoperative VT exacerbation. Epicardial implantation was associated with longer length; of hospital stay than transvenous implantation (p = 0.0005), independent of age, left ventricular ejection fraction, and concurrent cardiac surgery.