Optimal strength and number of shocks at upper limit of vulnerability testing required to predict high defibrillation threshold without inducing ventricular fibrillation

Background: The upper lim it of vulnerability (UL V) closely correlates with the defibrillation threshold (OFT) . The aim of th is study was to establish the optimal protocol for using the UL V test to predict high OFT (>20 J) without inducing ventricular fibrillation (VF) . Methods and Results: The 10-J and 15-J ULV test with 3 coupling intervals (-20, 0, and +20ms to the peak of T-wave) and the OFT test were performed in 96 patients receiving implantable cardioverter defibrillator. ULV ::; 10J was confirmed in 47 (49%). ULV ::; 15J was confirmed in 70 (77%) of 91 patients (15-J ULV test could not be done in 5). The sensitivity and negative predictive value of both ULV > 1 OJ and> 15J for predicting high OFT were 100%. The specificity and positive predictive value of ULV > 15 J were higher than those for ULV > 1 OJ (85% vs. 55%, 43% vs. 22%, respectively). The rate of VF inducibility for confirming ULV ::; 15J was lower than that for ULV ::; 10J (23% vs. 51 %, P