Evolving Concepts in Cardiac Physiologic Pacing in the Era of Conduction System Pacing

Cardiac physiologic pacing (CPP) has become a well-established therapy for patients with cardiomyopathy (left ventricular ejection fraction <35%) in the presence of a left bundle branch block. In addition, CPP can be highly beneficial in patients with pacing-induced cardiomyopathy and patients with existing cardiomyopathy expected to have a right ventricular pacing burden of >40%. The benefits of CPP with traditional biventricular pacing are only realized if adequate resynchronization can be achieved. However, left ventricular lead implantation can be limited by individual anatomic variation within the coronary venous system and can be adversely affected by underlying abnormal myocardial substrate (i.e., scar tissue), especially if located within the basal lateral wall. In the last 7 years the investigation of conduction system pacing (CSP) and its potential salutary benefits are being realized and have led to a rapid evolution in the field of cardiac resynchronization pacing. However, supportive evidence for CSP for patients eligible for cardiac resynchronization remains limited compared with data available for biventricular cardiac resynchronization, mostly derived from leading CSP investigative centers. In this review, we perform an up-to-date comprehensive review of the available literature on CPP.

Left ventricular endocardial pacing in the real world: Five years of experience at a single center

BACKGROUND

A left ventricular (LV) endocardial lead implant to achieve cardiac resynchronization therapy (CRT) is feasible when a conventional implant failed due to anatomical or technical issues or when the venous implant was performed but the patient did not respond to the therapy.

METHODS

Data about the implantation procedure (age, sex, clinical characteristics, anticoagulant use, and previous devices), patient characteristics (indication, technique used, lead model, complications), and follow-up (clinical and echocardiographic outcome, LV lead electrical measurements) were analyzed for all CRT systems implanted using LV endocardial lead, due to failed conventional implant or nonresponse, between April 2011 and November 2016.

RESULTS

Thirty-five patients were implanted with an active fixation LV endocardial lead during the study period, without significant complications. There were no dislodgements or severe complications related to the implant procedure in the follow-up period (36 ± 20 months) and a high percentage of patients responded to therapy, as assessed by several indicators.

CONCLUSIONS

An LV endocardial lead implant was feasible when the conventional technique had previously failed or was not effective. A high rate of response was achieved without any significant complications.

Advances in atrioventricular and interventricular optimization of cardiac resynchronization therapy - what's the gold standard?

INTRODUCTION

Cardiac resynchronization therapy (CRT) is one of the most important advances in heart failure management in the last twenty years. Approximately one-third of patients appear not to respond to therapy. Although there are a number of possible mechanisms for non-response, an important factor is suboptimal atrioventricular (AV) and interventricular (VV) timing intervals. There remains controversy over whether routinely optimizing intervals is necessary and there is no agreed gold standard methodology. Optimization has classically been performed using echocardiography which has limits related to resource use, time-cost and variable reproducibility. Newer optimization methods using device-based sensors and algorithms show promise in reducing heart-failure hospitalization compared with echocardiography. Areas covered: This review outlines the rationale for optimization, the principles of AV and VV optimization, the standard echocardiographic approach and newer device-based algorithms and the evidence base for their use. Expert commentary: The incremental gains of optimization are likely to be real, but small, compared to the overall improvement gained from cardiac resynchronization itself. At this time routine optimization may not be mandatory but should be performed where there is no response to CRT. Device-based optimization algorithms appear to be practical and in some cases, deliver superior clinical outcomes compared to echocardiography.

Update in cardiac arrhythmias and pacing

This article discusses the main advances in cardiac arrhythmias and pacing published between 2013 and 2014. Special attention is given to the interventional treatment of atrial fibrillation and ventricular arrhythmias, and on advances in cardiac pacing and implantable cardioverter defibrillators, with particular reference to the elderly patient.