DETERMINANTS OF NONTHORACOTOMY BIPHASIC DEFIBRILLATION

HORTON, R.P., ET AL.: Determinants of Nonthoracotomy Biphasic Defibril lation. The clinical variables affecting DFT for ICD systems are not c ompletely determined, especially with regard to biphasic shocking devi ces. To distinguish which factors correlate with DFT, we examined data from patients who where enrolled iu the Ventak P2/Endotak protocol. A total of 284 patients were enrolled in tile study. Two patients had a DFT > 25 J and did not receive the device; 154 did not undergo step d own to failure DFT testing. The remaining 128 patients had formal DFT testing and were suitable for analysis. Variables available for analys is included age, body surface area (BSA), LVEF, gender, lead configura tion, primary arrhythmia, primary cardiac disease, and use of cardioac tive medication. Data were evaluated using regression analysis, fittin g DFT (range, 1-25 J, mean 11 +/- 5 J) as a function of each variable. As a univariate predictor, BSA was found to be significant in predict ing DFT, but accounted for only 9 % of the total variation on the GIFT (P < 0.01, r = 0.3). This study suggests that DFT using a biphasic sh ocking waveform is modesty is influenced hy the BSA of the patient. Ot her specific factors, including LVEF, do not predict DFT.