BLOCK-HF: a game changer or a step too far?

Is conduction system pacing a panacea for pacemaker therapy?

INTRODUCTION

While supported by robust evidence and decades of clinical experience, right ventricular apical pacing for bradycardia is associated with a risk of progressive left ventricular dysfunction. Cardiac resynchronization therapy for heart failure with reduced ejection fraction can result in limited electrical resynchronization due to anatomical constraints and epicardial stimulation. In both settings, directly stimulating the conduction system below the atrio-ventricular node (either the bundle of His or the left bundle branch area) has potential to overcome these limitations. Conduction system pacing has met with considerable enthusiasm in view of the more physiological electrical conduction pattern, is rapidly becoming the preferred option of pacing for bradycardia, and is gaining momentum as an alternative to conventional biventricular pacing.

AREAS COVERED

This article provides a review of the current efficacy and safety data for both people requiring treatment for bradycardia and the management of heart failure with conduction delay and discusses the possible future roles for conduction system pacing in routine clinical practice.

EXPERT OPINION

Conduction system pacing might be the holy grail of pacemaker therapy without the disadvantages of current approaches. However, hypothesis and enthusiasm are no match for robust data, demonstrating at least equivalent efficacy and safety to standard approaches.

Update on Cardiac Resynchronisation Therapy for Heart Failure

Cardiac resynchronisation therapy (CRT) is well accepted therapy for the treatment of symptomatic systolic heart failure in defined patient subgroups. Large clinical trials over the past 20 years have shown that patients with a left ventricular (LV) systolic dysfunction and interventricular conduction delay benefit from this therapy. Recent advances in this field include the expansion indications for CRT to patients with mild heart failure and to those with a mildly depressed ejection fraction that require frequent right ventricular pacing. In addition, although CRT guidelines have included indications in atrial fibrillation, it is now clear that this is most effective when pacing is utilised nearly 100 % of the time, often requiring atrioventricular (AV) junction ablation. Strategies for optimising LV lead placement based on identifying late mechanical contraction or electrical delay are promising for maximising CRT response. Finally, the role of routine AV delay optimisation is no longer recommended based on the results of multicentre trials.