Long-term mortality risk in patients with an implantable cardioverter-defibrillator: Influence of heart rate and QRS duration

Background: A paucity of studies has investigated the role of autonomic cardiac regulation as well as cardiac conduction in relation to prognosis in implantable cardioverter-defibrillator (ICD) patients. Therefore, we examined the association of heart rate and QRS duration with long-term mortality risk in first-time ICD patients, adjusting also for measures of emotional distress. Methods: Resting heart rate and QRS duration were assessed prior to ICD implantation in 448 patients. Primary study endpoint was all-cause mortality (up to 6.0 year follow-up, median follow-up of 5.6 years (IQR: 1.9)). The impact of heart rate and QRS duration on time to all-cause mortality was separately assessed with Cox proportional hazard regression analysis, adjusting for clinical factors and symptoms of depression and anxiety. Results: Mean (SD) heart rate was 68.0 +/- 13.3 bpm and mean QRS duration was 130.9 +/- 36.9 ms. Heart rate of >= 80 bpm was associated with increased risk of mortality (HR = 1.86; 95% CI = 1.15-3.00; p = .011) in unadjusted analysis. In adjusted analyses, this relationship remained significant both with depression (HR = 1.86, 95% CI = 1.12-3.09; p = .017) and anxiety (HR = 1.82, 95% CI = 1.10-3.03; p = .021) and clinical measures as covariates. QRS duration of >= 120 ms was associated with impaired prognosis in unadjusted analysis (HR = 2.00, 95% CI = 1.27-3.14; p = .003), but was reduced to non-significance in adjusted analysis when medical comorbidities were included (HR = 1.15, 95% CI = 0.70-1.89; p = .60). Conclusions: This study shows that increased heart rate is associated with impaired prognosis. Since heart rate is a relatively easy measurable parameter of autonomic functioning, heart rate should be included as a measure for risk stratification in daily clinical practice. (C) 2014 Elsevier Ireland. Ltd. All rights reserved.