Response to (resynchronization) therapy in chronic heart failure: time for a different approach

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.

Percutaneous mitral annuloplasty with the Carillon device: Outcomes in proportionate and disproportionate functional mitral regurgitation

BACKGROUND

It has been suggested that the disparity of outcomes between the studies of transcutaneous edge-to-edge repair (TEER) for functional mitral regurgitation (FMR) in heart failure with reduced ejection fraction (HFrEF) could be due to systematic differences in the populations studied. One proposal is that there are 2 broad groups: those with proportional FMR who respond less favorably, and those in whom the FMR is greater than expected (disproportionate) FMR where edge-to-edge TEER seems to be more effective. Whether this grouping is relevant for other percutaneous interventions for FMR is unknown.

OBJECTIVES

We sought to compare clinical and echocardiographic outcomes of patients with HFrEF and proportionate and disproportionate FMR treated with indirect annuloplasty using the Carillon device.

METHODS

This is a pooled analysis from 3 trials of patients with FMR. Key patient eligibility in these trials specified persistent grade 2+ to 4+ FMR with >5.5 cm left ventricular (LV) end-diastolic diameter (LVEDD) and reduced ejection fraction. Patients with an effective regurgitant orifice area/LV end-diastolic volume (EROA/LVEDV) ratio under 0.15 were assigned to the proportionate FMR group (n = 74;65%) and those with a ratio above 0.15 were classed as having disproportionate FMR (n = 39;35%).

RESULTS

At 12 months following treatment, both groups showed improvements in all MR variables including regurgitation volume, EROA and vena contracta. Moreover, in patients with proportionate MR there were clinically relevant and statistically significant improvements in LV volumes and diameters. There was no independent relationship between the degree of proportionality as a continuous variable and the remodeling response to Carillon therapy (change in LVEDV r = 0.17; change in LVESV r = 0.14).

CONCLUSION

Percutaneous mitral annuloplasty with the Carillon device reduces MR in patients with both proportionate and disproportionate FMR, and also results in LV reverse remodeling in those with proportionate FMR. The effect on remodeling remains to be verified in a large-scale trial.

Beyond pharmacological treatment: an insight into therapies that target specific aspects of heart failure pathophysiology

Heart failure is a common syndrome associated with substantial morbidity and mortality. The management of symptoms and the strategies for improving prognosis have largely been based on pharmacological treatments. The pathophysiology of heart failure is complex because of the multiple causes responsible for this syndrome. This Series paper presents some examples of advances in heart failure management, in which the treatment specifically targets the underlying pathophysiological mechanisms responsible for the symptoms. These treatments include treatment of electromechanical dyssynchrony and dysrhythmia by cardiac resynchronisation and implantable cardioverter-defibrillators; neurohumoral modification by baroreflex and vagal stimulation; prevention of adverse cardiac remodelling by interatrial shunts; and finally targeting the myocardium directly by cell therapy in an attempt to regenerate new myocardial cells.