Resynchronization therapy in the context of atrial fibrillation: Benefits and limitations

Modalities of ventricular pacing for cardiac resynchronization therapy in patients with heart failure: a meta-analysis and systematic review

INTRODUCTION

This meta-analysis evaluated 14 studies which compared clinical and functional outcomes after different cardiac resynchronization therapy (CRT) modalities.

MATERIAL AND METHODS

Relevant studies were selected from the Medline, PubMed, Cochrane, and Google Scholar databases until June 27^th, 2016. We analyzed and compared the clinical outcomes (peak O₂ consumption and LVEF) and functional outcomes (6-min walk distance and quality of life (SF-36)) of HF patients who received different CRT modalities with outcomes in patients who received conventional univentricular therapy.

RESULTS

There was no significant difference in post-treatment 6-min walking distance between the biventricular (BiV) and left/right univentricular (LUV/RUV) groups (standardized difference in means = 0.049, 95% CI: -0.119 to 0.217, p = 0.566), or between the BiV and triventricular (TriV) groups (standardized difference in means = 0.035, 95% CI: -0.270 to 0.340, p = 0.822). Peak O₂ consumption was comparable between BiV and LUV/RUV groups (standardized difference in means = 0.306, 95% CI: -0.002 to 0.614, p = 0.052). Patients in the TriV group had a significant improvement in LVEF compared to the BiV group (standardized difference in means = 0.647, 95% CI: 0.313 to 0.982, p < 0.001).

CONCLUSIONS

TriV CRT is an attractive alternative to univentricular or BiV pacing for heart failure patients. It is necessary to conduct further large randomized trials to validate our present data.

A strategy to achieve CRT response in permanent atrial fibrillation without obligatory atrioventricular node ablation

BACKGROUND

Cardiac resynchronization therapy (CRT) is an established method in patients with severe heart failure and wide QRS configuration, particularly during sinus rhythm (SR). In CRT patients with permanent atrial fibrillation (AF), there is no general consensus regarding the need for atrioventricular node (AVN) ablation. The aim of this study was to evaluate the benefit of CRT in permanent AF with and without AVN ablation.

METHODS

New York Heart Association classification, QRS duration, and echocardiographic parameters were assessed before and after CRT with a follow-up of 12 ± 3 months. Two hundred thirty patients in SR and 46 patients with permanent AF of 2.1 ± 0.5 years duration were studied. AVN ablation was performed only in AF patients with insufficient pharmacological rate control evidenced by ≤80 % ventricular stimulation.

RESULTS

Fifteen AF patients underwent AVN ablation. Biventricular pacing comparably improved functional status, left ventricular ejection fraction, and left ventricular end-diastolic dimensions in all treated groups. Biventricular stimulation percentage was 10% lower in pharmacologically treated AF patients over 1 year as compared to patients in SR and to AF patients undergoing AVN ablation, which did not affect outcome in this patient population.

CONCLUSION

In patients with permanent AF and CRT, an AVN ablation strategy might not be strictly required in all patients.

[CRT in atrial fibrillation--methodical and apparatus options in decision-making]

Heart failure and atrial fibrillation often coexist, especially with increasing degree of heart failure severity. Under this constellation, the advantage of cardiac resynchronization therapy (CRT) is still under discussion and displayed as an unresolved problem in the guidelines for cardiac stimulation and resynchronization. If ventricular desynchronization can be documented and response to CRT can be expected, the challenge is to interoperatively seek the best left ventricular electrode position and to postoperatively optimize the device in order to achieve the best therapy performance. This situation encourages the development of individualized methods and to utilize innovative apparatus features in order to consolidate individual decisions and to optimize CRT in heart failure with atrial fibrillation.

The place of hybrid therapies with drugs to supplement nonpharmacological therapies in atrial fibrillation

Atrial fibrillation (AF) is one of the most common cardiac arrhythmias, and its prevalence continues to rise as the aged population increases. Comparative studies of rhythm control and rate control have been equivocal; however, the benefits of rhythm control may have been offset by the limitations of antiarrhythmic drugs. More recently, nonpharmacological therapies have emerged that provide hope of more effective rhythm control. Catheter ablation techniques have gained favour with high success rates in specialized centers, although these techniques are not without complications and require considerable expertise. Pacing therapies designed to reduce harmful right ventricular pacing and increase physiological pacing have shown benefit in AF patients with bradycardia. Despite this progress, no single modality confers benefit for all patients. Strategies to combine these treatment modalities in a hybrid approach has shown increasing promise for subgroups of AF patients.