Risk factors for ventricular tachyarrhythmic events in patients without left bundle branch block who receive cardiac resynchronization therapy.

Abstract

IntroductionCardiac resynchronization therapy (CRT) may be pro‐arrhythmic in patients with non‐left bundle branch block (non‐LBBB). We hypothesized that combined assessment of risk factors (RF) for ventricular tachyarrhythmias (VTAs) can be used to stratify non‐LBBB patients for CRT implantation.MethodsThe study comprised 412 non‐LBBB patients from MADIT‐CRT randomized to CRT‐D (n = 215) versus ICD only (n = 197). Best‐subset regression analysis was performed to identify RF associated with increased VTA risk in CRT‐D patients without LBBB. The primary end point was first occurrence of sustained VTA during follow‐up. Secondary end points included VTA/death and appropriate shock.ResultsFour RFs were associated with increased VTA risk: blood urea nitrogen >25mg/dl, ejection fraction <20%, prior nonsustained VT, and female gender. Among CRT‐D patients, 114 (53%) had no RF, while 101 (47%) had ≥1 RF. The 4‐year cumulative probability of VTA was higher among those with ≥1 RF compared with those without RF (40% vs. 14%, p < .001). Multivariate analysis showed that in patients without RF, treatment with CRT‐D was associated with a 61% reduction in VTA compared with ICD‐only therapy (p = .002), whereas among patients with ≥1 RF, treatment with CRT‐D was associated with a corresponding 73% (p = .025) risk increase. Consistent results were observed when the secondary end points of VTA/death and appropriate ICD shocks were assessed.ConclusionCombined assessment of factors associated with increased risk for VTA can be used for improved selection of non‐LBBB patients for CRT‐D.