Abstract 2844: Right Ventricular Stimulation Threshold at ICD implant Predicts Device Therapy and Mortality in Primary Prevention Patients With Ischemic Heart Disease
Objective: Myocardial excitability is known to be related to the degree of ischemia, contractile dysfunction and heart failure. It was hypothesized that the right ventricular (RV) stimulation threshold has prognostic value with respect to the occurrence of ventricular arrhythmias (VAs) and patient survival in recipients of an implantable cardioverter defibrillator (ICD).
Methods: Ischemic heart disease patients receiving an ICD as primary prevention for sudden cardiac death were included in this study. RV-thresholds were determined at ICD implant. During follow-up, data were collected on VAs triggering ICD therapy and on all-cause mortality.
Results: A total of 689 consecutive patients were included in the current study (87% male, age 63±11 years, left ventricular ejection fraction 29±11%) and followed for 33±22 months. Post-implant RV-threshold was 0.7±0.5volt (V) at 0.5ms pulse duration. Best dichotomous separation was reached at a cut-off of 1V. During follow-up, 167(24%) patients received appropriate ICD therapy, 88(13%) had appropriate shocks and 134(19%) died. Cumulative appropriate shock incidence for patients with a RV-threshold ≥1V (n=166) was 16% at 1 year, 24% at 3 years and 34% at 5 years compared to 4%, 11% and 17% for patients with a RV-threshold <1V (n=523)(Figure⇓). Adjusted Hazard Ratio (HR) of RV-threshold ≥1V was 1.8 (95% CI 1.3–2.6) for appropriate therapy, 3.3 (95%CI 2.0 –5.4) for appropriate shocks and 1.6 (95%CI 1.1–2.5) for mortality.
Conclusion: The RV stimulation threshold at ICD implant has a strong independent prognostic value for the occurrence of ventricular arrhythmias triggering appropriate ICD therapy, appropriate shocks and mortality.