Key result
An RV stimulation threshold ≥ 1 V at ICD implant was associated with an increased risk of appropriate ICD therapy (HR 2.0; 95% CI 1.4-2.9) and appropriate shocks.
Why the study?
Does an RV stimulation threshold ≥ 1 V at ICD implant predict appropriate ICD therapy, shocks, and mortality in primary prevention patients with ischaemic heart disease?
Cohort (n=689)
No
Does an RV stimulation threshold ≥ 1 V at ICD implant predict appropriate ICD therapy, shocks, and mortality in primary prevention patients with ischaemic heart disease?
An RV stimulation threshold ≥ 1 V at ICD implant is a strong independent predictor of appropriate ICD therapy, shocks, and mortality in patients with ischaemic heart disease receiving a primary prevention ICD.
May aid risk stratification in ischaemic primary-prevention ICD recipients; leaves open prospective confirmation before practice change.
AIMS: Myocardial excitability is known (amongst other reasons) to be related to the degree of ischaemia, 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 AND RESULTS: Ischaemic heart disease patients receiving an ICD at Leiden University Medical Center as primary prevention for sudden cardiac death were included in this study. Right ventricular thresholds were determined at ICD implant. Data were collected on VAs triggering ICD therapy and on all-cause mortality. A total of 689 consecutive patients were included (87% male, age 63 ± 11 years, left ventricular ejection fraction (LVEF) 29 ± 11%) and followed for a median of 28 months. Post-implant RV-threshold was 0.7 ± 0.5 volt (V) at 0.5 ms pulse duration. Best dichotomous separation was reached at a cut-off of 1 V. 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 RV threshold ≥ 1 V (n = 166) was 16% at 1 year, 24% at 3 years and 34% at 5 years compared with 4, 11 and 17% for patients with an RV-threshold < 1 V (n = 523). Adjusted hazard ratio of RV threshold ≥ 1 V was 2.0 (95% CI: 1.4-2.9) 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 VAs triggering appropriate ICD therapy, appropriate shocks and mortality.
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Atary et al. (2010) conducted a cohort in Ischaemic heart disease (n=689). Right ventricular stimulation threshold ≥ 1 V vs. Right ventricular stimulation threshold < 1 V was evaluated on Appropriate ICD therapy (HR 2.0, 95% CI 1.4-2.9). An RV stimulation threshold ≥ 1 V at ICD implant was associated with an increased risk of appropriate ICD therapy (HR 2.0; 95% CI 1.4-2.9) and appropriate shocks.
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