The following is a summary of “RISK OF VENTRICULAR TACHYARRHYTHMIAS IN CARDIAC RESYNCHRONIZATION THERAPY DEVICE RECIPIENTS,” published in the March 2023 issue of Cardiology by Goldenberg, et al.

The efficacy of cardiac resynchronization therapy (CRT) in preventing life-threatening ventricular tachyarrhythmias (LT-VTA) has been debated, and the hypothesis that the effects may be related to the underlying QRS morphology was tested. 

The study analyzed a population of 2,862 patients with a QRS duration of ≥130 ms who had received an implantable cardioverter-defibrillator (ICD) or a CRT defibrillator (CRT-D) for primary prevention in five significant ICD trials (MADIT-II, MADIT-CRT, MADIT-RIT, MADIT-RISK, and RAID). Patients were compared based on whether they had received an ICD or CRT-D, with endpoints being life-threatening ventricular tachyarrhythmias (defined as VT≥200 bpm or ventricular fibrillation) and appropriate ICD shock.

The study found that among patients with left bundle branch block (LBBB) (N=1792), CRT-D was associated with a 45% (HR=0.55; P<0.001) reduction in the burden of LT-VTA and a reduced burden of appropriate ICD shocks (HR=0.44; P<0.001). On the other hand, NLBBB patients with CRT-D experienced a 90% (HR=1.90; P=0.01) increase in the burden of LT-VTA and a higher burden of appropriate shocks (HR=1.63; P=0.072).

The study concluded that the effect of CRT on arrhythmias was linked to QRS morphology and must be taken into consideration when selecting patients for CRT implantation.

Source: jacc.org/doi/10.1016/S0735-1097%2823%2900448-5