Review Article
Extending the Boundaries of Cardiac Resynchronization Therapy: Efficacy in Atrial Fibrillation, New York Heart Association Class II, and Narrow QRS Heart Failure Patients

https://doi.org/10.1016/j.cardfail.2009.12.018Get rights and content

Abstract

Background

Large-scale clinical trials have demonstrated the benefits of cardiac resynchronization therapy (CRT) in patients with New York Heart Association (NYHA) Class III/IV heart failure, systolic left ventricular dysfunction, and a wide QRS. However, additional patient groups may also benefit from CRT.

Methodsand Results

We meta-analyzed clinical benefits of CRT in heart failure patients with narrow QRS, atrial fibrillation (AF) and NYHA Class II symptoms. Thirteen trials of 2882 patients contributed to this meta-analysis. In the narrow versus wide QRS group comparison, no difference in benefit was observed for change in left ventricular ejection fraction (standardized mean difference [SMD] 0.30, 95% confidence interval [CI] −0.37 to 0.97) or left ventricular end systolic volume (SMD 0.30, 95% CI −1.14 to 1.74). The benefit was greater in the wide QRS group for the 6-minute walk test (SMD 1.27, 95% CI 0.59 to 1.96) and NYHA class improvement (SMD 1.24, 95% CI 0.72 to 1.75). In the atrial fibrillation (AF) versus sinus rhythm (SR) group comparison, no difference in benefit was observed for change in left ventricular ejection fraction (SMD −0.38, 95% CI −1.28 to 0.53) or NYHA improvement (SMD 0.32, 95% CI −0.77 to 1.40). In the NYHA II versus NYHA III/IV group comparison, no difference in benefit was observed for change in left ventricular end diastolic diameter (SMD 0.05, 95% CI -0.94 to 1.05) or left ventricular end systolic diameter (SMD 0.74, 95% CI −1.98 to 3.46).

Conclusions

Large-scale clinical outcome trials of CRT are warranted in heart failure patients with narrow QRS, AF, and NYHA II, given the similar benefits observed to those with wide QRS, SR, and NYHA III/IV for many parameters.

Section snippets

Methods

Studies were eligible for inclusion in this meta-analysis if they compared the benefits of CRT between patients with (1) narrow QRS and wide QRS, (2) AF and SR, or (3) NYHA Class II and NYHA Class III/IV symptoms. Studies that described the benefits of CRT in patients with narrow QRS, SR, or NYHA II in comparison to similar patients who did not receive CRT were not able to be meta-analyzed because of the paucity of such studies. To compare and pool study results, “narrow QRS” was defined in

Results

Our search for studies, conducted in accordance with the Quality of Reporting of Meta-analyses (QUOROM) statement, is summarized in Figure 1. We identified 227 potentially suitable articles. Of these, 17 met our inclusion criteria. Four of these studies were not included in the analysis, as they did not report end points, which were also reported in at least 2 other studies6, 7, 8 or did not provide all the required data for meta-analysis.9 The remaining 13 studies were analyzed.10, 11, 12, 13,

Discussion

The results of this study demonstrate that CRT may potentially have applications beyond the current standard indications of SR, NYHA Class III/IV symptoms, widened QRS, and LVEF <35%.

A similar improvement in NYHA class and LVEF was observed in patients with atrial fibrillation and those in sinus rhythm. In addition, this study demonstrated a similar benefit from CRT in patients with NYHA Class II compared with NYHA Class III/IV symptoms for the end points of left ventricular end-diastolic

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Prof Henry Krum is on the executive committee of the EchoCRT trial, which is sponsored by Biotronik, Inc.

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