Elsevier

Heart Rhythm

Volume 10, Issue 7, July 2013, Pages 943-950
Heart Rhythm

Clinical significance of ventricular tachyarrhythmias in patients treated with CRT-D

https://doi.org/10.1016/j.hrthm.2013.04.006Get rights and content

Background

Data on the outcome of cardiac resynchronization therapy with defibrillator (CRT-D) in patients developing ventricular arrhythmias are limited.

Objective

To evaluate the prognostic value of ventricular tachycardia (VT) or ventricular fibrillation (VF) episodes by heart rate in patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy trial.

Methods

Slow VT was defined as VTs with heart rate < 200 beats/min. Fast VT with a heart rate ≥200 beats/min and VF (>250 beats/min) were considered as a combined category. Primary end point was heart failure (HF) or death. Secondary end point included all-cause mortality.

Results

There were 228 (12.7%) patients with slow VT and 198 (11.1%) with fast VT/VF. In time-dependent analysis, slow VT was associated with an increased risk of HF/death in CRT-D patients with left branch bundle block (LBBB; hazard ratio [HR] 3.19; 95% confidence interval [CI] 1.83–5.55; P < .001), but not in patients with implantable cardioverter-defibrillator (ICD) (HR 1.03; 95% CI 0.52–2.19; P = .867; interaction P value = .017). CRT-D patients with LBBB and fast VT/VF doubled their risk of HF/death compared to ICD patients (interaction P value = .06). Slow VT events were also predictive of death in CRT-D patients with LBBB (HR 3.48; 95% CI 1.66–7.28; P < .001), but not in ICD patients (interaction P value = .06). Slow VTs were highly predictive of subsequent fast VT/VF (HR 4.33; 95% CI 3.01–6.24; P < .001).

Conclusions

Slow VT episodes are predictive of subsequent fast VT/VF. Slow VT and fast VT/VF episodes in CRT-D patients are associated with an increased risk of subsequent HF/death. CRT-D-treated LBBB patients with slow VTs have a significantly higher risk of mortality.

Introduction

Cardiac resynchronization therapy (CRT) has been shown to reduce heart failure (HF) hospitalizations, to induce left ventricular (LV) reverse remodeling, and to reduce mortality in moderate to severe1, 2, 3, 4, 5, 6, 7 and mild8, 9 HF patients. The Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy (MADIT-CRT) trial8 and the Resynchronization-Defibrillation in Ambulatory Heart Failure Trial (RAFT)9 demonstrated that left bundle branch block (LBBB) patients benefit more from CRT than do non-LBBB patients, including patients with right bundle branch block (RBBB) and intraventricular conduction delay (IVCD).

Cardiac resynchronization therapy with defibrillator (CRT-D) treatment is associated with significant reduction in ventricular tachyarrhythmias in patients with LBBB, but not in those with non-LBBB.10 However, patients remain at a high risk of ventricular tachycardia (VT) and ventricular fibrillation (VF) even after receiving a CRT device.11 The outcome of CRT-D patients after a VT or VF event is less investigated.

However, ventricular tachyarrhythmia episodes were shown to be associated with adverse clinical outcome in patients with implantable cardioverter-defibrillator (ICD).12, 13 Some studies indicated that ICD shocks, including both appropriate and inappropriate therapies, increase the risk of all-cause mortality in patients with ICD,14, 15 although the effects of ventricular arrhythmias on subsequent HF/death, especially in patients with CRT-D were less investigated.

The aim of the present study was to evaluate the prognostic value of ventricular tachyarrhythmias with regard to arrhythmia cycle length in ICD and CRT-D patients separately, stratified by LBBB at baseline, (1) on subsequent HF/death, (2) on death alone, and (3) on subsequent ventricular arrhythmias, with a focus on slow ventricular tachyarrhythmia events in patients with mild HF enrolled in the MADIT-CRT trial.

Section snippets

Study population

The design, protocol, and results of MADIT-CRT had been published earlier.8, 16 The MADIT-CRT study was designed to evaluate whether CRT-D therapy would reduce the primary end point of HF/death in mildly symptomatic or asymptomatic HF patients, namely, ischemic cardiomyopathy with New York Heart Association (NYHA) class I or II or nonischemic cardiomyopathy with NYHA class II, severe LV dysfunction (LV ejection fraction) ≤30%, and a prolonged QRS duration of ≥130 ms.

In this prospective,

Results

There were 131 (12.1%) patients with CRT-D and 97 (13.6%) patients with ICD with slow VT and 103 (9.6%) patients with CRT-D and 95 (13.3%) patients with ICD with fast VT/VF. Furthermore, 843 (78.3%) patients with CRT-D and 520 (73%) patients with ICD had no VT or VF events during the mean follow-up period of 40 ± 13 months. Eighty patients developed both slow VT and fast VT/VF during the course of the trial.

Discussion

Our study suggests that slow VT episodes with a heart rate <200 beats/min are particularly predictive of subsequent HF/death in CRT-D patients with LBBB, but not in those with an implanted ICD and LBBB. Slow VTs were highly predictive of subsequent fast VT/VF in this analysis. Furthermore, slow VT episodes with a heart rate <200 beats/min were significantly predictive of subsequent all-cause mortality in CRT-D patients with LBBB, but not in those with an ICD or non-LBBB. In CRT-D patients with

Conclusions

In mild HF patients, slow VT events are prognostic of subsequent HF/death or death alone in patients with CRT-D and LBBB, despite the beneficial response to CRT-D. Slow VTs are also predictive of subsequent fast VT/VF. Fast VT/VF episodes are particularly predictive of HF or death in patients with CRT-D, but less so in patients with ICD. Patients with both slow VT and fast VT/VF have adverse clinical outcome. Close follow-up and enhanced medical treatment is warranted in CRT-D patients,

References (23)

  • J.G. Cleland et al.

    The effect of cardiac resynchronization on morbidity and mortality in heart failure

    N Engl J Med

    (2005)

    • The Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy study was supported by a research grant from Boston Scientific to the School of Medicine and Dentistry, University of Rochester.

    Dr Kutyifa has received research support from Boston Scientific and honoraria from Biotronik and Servier. Dr Moss and Dr Zareba have received research grant from Boston Scientific. Dr Wang has received EP fellowship support from Medtronic, St Jude, and Boston Scientific; honoraria from Medtronic and Boston Scientific; and research support from Medtronic. Dr Merkely has received consultant fees/honoraria from Boston Scientific.

    View full text
    Published by Elsevier Inc.