PREDICTORS OF DEFIBRILLATION ENERGY-REQUIREMENTS WITH NONEPICARDIAL LEAD SYSTEMS

The determinants of high defibrillation energy requirements (DER) usin g nonepicardial lead systems (NELS) have not been well characterized. The goal of this study was to examine prospectively the influence of c linical, radiographic, echocardiographic, and procedural variables on DER during NELS placement. Data from 100 consecutive patients undergoi ng attempted NELS implantation were analyzed. Transvenous leads, subcu taneous patches, and monophasic shock devices from two manufacturers w ere used. Leads were successfully positioned for testing in 95% of pat ients. An adequate DER (less than or equal to 25 J) was obtained in 73 of 95 (77%) of patients. Univariate analysis identified amiodarone th erapy and left ventricular mass as predictors of high DER. With multiv ariate analysis, amiodarone therapy was the sole significant predictor of high DER (P = 0.002, odds ratio 5.46). The 22 patients with high N ELS DER also had high epicardial DER (mean 24 +/- 9 J). The two patch epicardial DER was 25 joules in 22 of 22 patients. Thus, adequate DER with monophasic shock waveforms can be obtained in most patients under going NELS testing. However, amiodarone therapy significantly increase s the probability of obtaining high DER.