B-PO05-047 EVALUATION OF MECHANICAL PLACEMENT, IMPEDANCE, AND LOW VOLTAGE MEASUREMENT COROLLARY STUDY (EMILY STUDY) FOR THE S-ICD

Abstract

The subcutaneous implantable cardioverter defibrillator (S-ICD) high voltage impedance (HVZ) inversely correlates with the probability of defibrillation success. Impedance at implant may be a good surrogate for coil depth. The S-ICD performs commanded and periodic low voltage lead integrity checks at ≈ 1 V as compared to > 1000 V during a 65J or 80 J Shock. Correlation between low voltage impedance (LVZ) and high voltage impedance for the S-ICD system has not been performed. Correlating LVZ and HVZ may allow implanters to predict VF conversion outcome before testing. Determine what LVZ measurements best estimate HVZ. Consented patients undergoing S-ICD implant at Riverside Methodist Hospital, Columbus OH were reviewed. S-ICD impedance values were analyzed after electrode connection (LVZ1), after first layer skin closure (LVZ2), and shortly before Induction Testing (LVZ3) and compared to High Voltage shock (HVZ). Dunnett’s method was used to determine which LVZ measurement provides the best estimate for HVZ. For 41 patients (67.5% male, mean age: 58.4±14.6 years, ejection fraction (EF) = 32.23%±13.02; BMI 32.22±10.78), LVZ3 measurement had the smallest offset from HVZ, (95% confidence limits (CL) 0.03 - 5.68 Ω). LVZ3 and HVZ strongly correlate with a Pearson r=0.889. LVZ consistently has a smaller offset from HVZ as the time of LVZ measurement approaches induction testing. LVZ3 is within 10 Ω of HVZ for 83% of patients. Low Voltage Impedance immediately prior to induction testing provides the most accurate estimate for High Voltage Impedance. The LVZ can be used as one indicator of device placement prior to induction testing.