Recent Advances in the Optimization of Cardiac Resynchronization Therapy

Cardiac resynchronization therapy: a comprehensive review

Despite improved understanding of heart failure (HF) and advances in medical treatments, its prevalence continues to rise, and the role of implantable devices continues to evolve. While cardiac resynchronization therapy (CRT) is an accepted form of treatment for many suffering from HF, there is an ever-evolving body of evidence examining novel indications, optimization of lead placement and device programming, with several competing technologies now also on the horizon. This review aims to take a clinical perspective on the major trials, current indications, controversies and emerging aspects of CRT in the treatment of HF.

Developments in Cardiac Resynchronisation Therapy

Cardiac resynchronisation therapy (CRT) is an important therapy for patients with heart failure with a reduced ejection fraction and interventricular conduction delay. Large trials have established the role of CRT in reducing heart failure hospitalisations and improving symptoms, left ventricular (LV) function and mortality. Guidelines from major medical societies are consistent in support of CRT for patients with New York Health Association (NYHA) class II, III and ambulatory class IV heart failure, reduced LV ejection fraction and QRS prolongation, particularly left bundle branch block. The current challenge facing practitioners is to maximise the rate of patients who respond to CRT and the magnitude of that response. Current areas of interest for achieving these goals include tailoring patient selection, individualising LV lead placement and application of new technologies and techniques for CRT delivery.

Current Technology to Maximize Cardiac Resynchronization Therapy Benefit for Patients With Symptomatic Heart Failure

The incidence of heart failure (HF) continues to increase, affecting millions of people in the United States each year. Cardiac resynchronization therapy (CRT) has been used and studied for patients with symptomatic HF for more than 20 years. The purpose of this article is to review technologies and developments to help maximize CRT for patients with symptomatic HF. Although most interventions to optimize CRT are physician directed, nurses also have an important role in the care and education of patients with symptomatic HF and can affect clinical outcomes. Therefore, nurses’ understanding of CRT and measures to maximize this lifesaving therapy is critical in HF management.

Complete left bundle branch block and smaller left atrium are predictors of response to cardiac resynchronization therapy in advanced heart failure

BACKGROUND

We previously reported that cardiac resynchronization therapy with defibrillator (CRT-D) is not an appropriate rescue strategy in patients with advanced heart failure (HF), especially those dependent on inotrope infusion, and instead early ventricular assist device (VAD) implantation should be considered. Predictors of response to CRT in such populations, however, remain uncertain.

METHODS AND RESULTS

We studied 67 inpatients aged <65 years old with advanced HF, who received CRT-D between 2007 and 2014. Eleven patients (16%) were responders, in whom LVEF improved >10% at 6-month follow up. On logistic regression analysis, LA volume index (LAVI) <43 ml/m(2)(odds ratio (OR), 36.67; P=0.001) and complete left bundle branch block (CLBBB; OR, 6.663; P=0.032) were significant predictors of response to CRT-D among the baseline variables. Patients with both predictors were associated with improvements in LVEF and plasma B-type natriuretic peptide compared with those with none of these predictors during the 6-month follow up period (P<0.05 for both). VAD-free survival rate was significantly higher in the responders compared with the non-responders during the 2-year study period (86% vs. 52%, P=0.044).

CONCLUSIONS

CLBBB and smaller LAVI are novel predictors of response in patients with advanced HF receiving CRT-D in real-world practice. Such responders may be better candidates for CRT-D and delay of cardiac replacement therapy.