Improving Cardiac Resynchronisation Therapy

Q: What is the clinical evidence from this study?

Study design: Review. Population: Heart failure with reduced ejection fraction (HFrEF). Intervention: Cardiac resynchronisation therapy (CRT) optimisation strategies (including patient selection, multimodality imaging/electrical mapping-guided lead placement, LV endocardial pacing, multipoint pacing, His bundle pacing, and dynamic AV/VV timing algorithms) vs. Conventional CRT delivery and nominal device programming.

George Thomas; Jiwon Kim; Bruce B. Lerman

doi:10.15420/aer.2018.62.3

August 9, 2019Arrhythmia & Electrophysiology ReviewOpen Access

Improving Cardiac Resynchronisation Therapy

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Key result

CRT fails in ~30% of heart failure patients, but tailored delivery and alternative pacing improve response.

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Why the study?

Do advanced patient selection criteria, targeted LV lead placement, alternative pacing strategies (endocardial, multipoint, His bundle), and dynamic AV/VV optimisation algorithms improve clinical response and outcomes in HFrEF patients undergoing CRT?

Key Points

To review technological advances and clinical strategies that refine patient selection, guide lead placement, and implement alternative pacing techniques in cardiac resynchronisation therapy.
Narrative review synthesizing evidence from major clinical trials, imaging studies, and electrophysiological investigations of cardiac resynchronisation therapy (CRT).
Evaluated physiological criteria, including QRS morphology, QRS duration, echocardiographic dyssynchrony indices, cardiac MRI, and electrocardiographic mapping techniques.
In the PREDICT-CRT trial of 1,060 patients, the presence of both apical rocking and septal flash yielded a 15% reduction in left ventricular end-systolic volume in 77% of patients, compared to 69% for apical rocking alone and 56% for septal flash alone.
Targeting viable myocardium rather than scar tissue and deploying alternative pacing modalities, such as His bundle pacing or endocardial pacing, overcome anatomic barriers and improve synchronisation.

Structured PICO

Do advanced patient selection criteria, targeted LV lead placement, alternative pacing strategies (endocardial, multipoint, His bundle), and dynamic AV/VV optimisation algorithms improve clinical response and outcomes in HFrEF patients undergoing CRT?

P

Population

Patients with heart failure and reduced ejection fraction (HFrEF) receiving or eligible for cardiac resynchronisation therapy (CRT), where approximately 30% of treated patients do not derive clinical benefit.

I

Intervention

Strategies to improve CRT response, including refined patient selection (QRS duration/morphology, echocardiography, cardiac MRI, vectorcardiography, ECGI), targeted LV lead placement in late-activating viable myocardium, LV endocardial pacing (transseptal, intraventricular septal, leadless WiSE-CRT), multisite/multipoint LV pacing, His bundle pacing, and dynamic AV/VV timing optimisation algorithms (AdaptiveCRT, SonR, SyncAV, QuickOpt, SmartDelay)

C

Comparator

Standard / conventional epicardial coronary sinus CRT delivery and nominal device settings

O

Outcome

Clinical and echocardiographic CRT response, left ventricular reverse remodelling, heart failure hospitalisation, and all-cause mortality

This comprehensive review outlines clinical strategies to overcome the ~30% non-responder rate in CRT through improved patient selection, multimodality imaging and electrical mapping for lead placement, dynamic device programming, and alternative pacing techniques such as LV endocardial and His bundle pacing.

Limitations

In 5–10% of patients, LV lead placement is unsuccessful due to coronary sinus inaccessibility, high LV pacing thresholds, or phrenic nerve stimulation.
More than 50% of patients have only one coronary sinus branch suitable for lead placement, limiting targeted placement.
LV endocardial pacing with transseptal atrial placement is associated with thromboembolic complications (stroke rate of 2.6 per 100 patient-years in ALSYNC).
His bundle pacing currently lacks large randomised trials showing clinical or mortality benefit, and has high lead revision rates, higher thresholds, and greater battery drain.
No standardised definition of LBBB exists with respect to predicting electrical dyssynchrony and response to CRT.
Echocardiographic speckle-tracking approaches for targeted lead placement are limited by the availability of specialised software and the need for optimal image quality.
Coronary sinus anatomy limits epicardial LV lead placement in 5–10% of patients, and >50% have only one suitable CS branch.
Transseptal LV endocardial pacing carries a high rate of thromboembolic complications despite anticoagulation.
His bundle pacing is limited by a lack of large randomised clinical trials, high lead revision rates, higher capture thresholds, and increased battery drain.

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Implication

Advanced CRT strategies remain hypothesis-generating; leaves open randomized validation of selection, lead placement, and alternative pacing in HFrEF.

Abstract

CRT is a cornerstone of therapy for patients with heart failure and reduced ejection fraction. By restoring left ventricular (LV) electrical and mechanical synchrony, CRT can reduce mortality, improve LV function and reduce heart failure symptoms. Since its introduction, many advances have been made that have improved the delivery of and enhanced the response to CRT. Improving CRT outcomes begins with proper patient selection so CRT is delivered to all populations that could benefit from it, and limiting the implantation of CRT in those with a small chance of response. In addition, advancements in LV leads and delivery technologies coupled with multimodality imaging and electrical mapping have enabled operators to place coronary sinus leads in locations that will optimise electrical and mechanical synchrony. Finally, new pacing strategies using LV endocardial pacing or His bundle pacing have allowed for CRT delivery and improved response in patients with poor coronary sinus anatomy or lack of response to traditional CRT.

Discussion

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Cite This Study

Thomas et al. (2019) conducted a review in Heart failure with reduced ejection fraction (HFrEF). Cardiac resynchronisation therapy (CRT) optimisation strategies (including patient selection, multimodality imaging/electrical mapping-guided lead placement, LV endocardial pacing, multipoint pacing, His bundle pacing, and dynamic AV/VV timing algorithms) vs. Conventional CRT delivery and nominal device programming was evaluated. Cardiac resynchronisation therapy fails to benefit approximately 30% of heart failure patients, which can be improved via refined selection, targeted lead placement, and alternative pacing.

synapsesocial.com/papers/6a7c91961b0fae09726ee122 https://doi.org/10.15420/aer.2018.62.3

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Improving Cardiac Resynchronisation Therapy

Figures

Key Points

Structured PICO

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

Improving Cardiac Resynchronisation Therapy

Figures

Key Points

Structured PICO

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

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