QRS complex widening as a predictor of appropriate implantable cardioverter−defibrillator (ICD) therapy and higher mortality risk in primary prevention ICD patients

Abstract

Background and aim: Effectiveness of implantable cardioverter-defibrillators (ICD) in patients with reduced left ventricular ejection fraction after myocardial infarction has been documented in large randomised trials. We analysed the predictive value of clinical factors at the time of implantation for adequate ICD interventions and mortality risk.
Methods: We analysed 121 consecutive patients (15 women, 106 [88%] men; mean age 62 ± 10 years) with coronary artery disease in whom ICD was implanted for primary prevention between 2001 and 2007. Mean duration of follow-up was 876 ± 538 days.
Results: Forty-four (36.4%) patients had adequate ICD interventions. In the Cox analysis, wider QRS complexes (hazard ration [HR] per each 10 ms increment: 1.13, confidence interval [CI] 1.039–1.229, p = 0.0045) and younger age at the time of ICD implantation (HR per each 10 year increment: 0.7, CI 0.5–0.9, p = 0.0081) were associated with a higher probability of adequate intervention. Wider QRS complexes were associated with a higher probability of electrical storm (HR 1.059, CI 1.014–1.045, p = 0.0002). During follow-up, 21 (17.4%) patients died. In the Cox analysis, wider QRS complexes (HR per each 10 ms increment: 1.123, CI 1.011–1.248, p = 0.0306 [in univariate analysis only]), older age at the time of implantation (HR per each 10 year increment: 1.7, CI 1.1–2.8, p = 0.0396) and higher NYHA class (HR 4.4, CI 1.7–11.5, p = 0.0022) were associated with increased mortality. Mortality was reduced by previous revascularisation (HR 0.3, CI 0.1–0.7, p = 0.006).
Conclusions: Patients with wider QRS complexes at the time of ICD implantation had a higher probability of adequate device intervention and mortality risk. QRS complex widening was also associated with a higher incidence of electrical storm.