Refining Patient Selection Criteria for LV-Only Fusion Pacing in Cardiac Resynchronization Therapy: A Systematic Review

Abstract

Objectives: This review aims to systematically evaluate the clinical outcomes of left ventricle-only fusion pacing (LV-only fCRTp) and identify evidence-based selection criteria that may optimize patient response and long-term therapeutic benefit. Background: Cardiac resynchronization therapy (CRT) is traditionally associated with biventricular pacing (BiVp). However, approximately 20-40% of patients seem to remain non-responders to this therapy. LV-only fCRTp offers a more physiological alternative by combining left ventricular epicardial pacing with the intrinsic ventricular activation wavefront. Beyond optimization strategies, the observed variability in response highlights the need for better patient selection in order to fully unlock its therapeutic potential. Methods: A systematic literature search was conducted in PubMed and Cochrane Library for original articles published up to April 2025, following PRISMA 2020 guidelines. The search focused on LV-only fCRTp performed either through standard RA/LV/RV biventricular devices or RA/LV dual-chamber systems. Results: Twenty-seven studies met the inclusion criteria. Among these, 17 studies obtained LV-only fCRTp using biventricular devices, and 10 were considered true LV-only fCRTp using RA/LV dual-chamber devices. Standard and specific selection criteria were used to qualify patients for LV-only fCRTp. Preserved atrioventricular conduction, ischemic cardiomyopathy, arrhythmic risk stratification, and the management of supraventricular arrhythmias were common overlapping parameters among studies with high variability, highlighting their potential role in response. RA/LV devices yielded consistent clinical benefits and low complication rates, particularly in nonischemic patients with stable AV conduction and low arrhythmic risk, while having a lower financial burden. Conclusions: Beyond guideline recommendations for CRT, this review identifies supplementary selection criteria that could further influence the effectiveness and stability of fusion pacing.

Keywords: CRT; LV-only; RA/LV dual-chamber device; biventricular pacing; cardiac resynchronization therapy; fusion; physiologic pacing; responder; selection criteria; univentricular pacing.

Figure A1

Risk of Bias 2.0 assessment for parallel-group randomized controlled trials [13,17,19,20,21,22,23,24,28,35].

Figure A2

Risk of Bias 2.0 assessment for crossover randomized controlled trials [14,18,25,30,32].

Figure A3

MINORS quality assessment for non-randomized studies [15,16,26,27,29,31,33,34,36,37,38,39].

Figure 1

PRISMA 2020 flow diagram of study selection process.

Figure 2

Distribution of common standard selection criteria for LV-only fCRTp.

Figure 3

Comparative heatmap summarizing the inclusion criteria and clinical outcomes of studies evaluating LV-only fCRTp versus BiVp. Each column represents a study, while each row denotes a specific inclusion criterion. Color coding reflects the clinical outcome of LV-only fCRTp compared to BiVp: yellow—similar outcomes between LV-only fCRTp and BiVp; green—superior outcome with LV-only fCRTp; red—inferior outcome with LV-only fCRTp [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29].

Figure 4

Proportion of ischemic patients in LV-only fCRT group from studies that reported similar outcomes with BiVp [13,14,15,16,17,18,19,20,25].

Figure 5

Proportion of ischemic patients in studies reporting superior outcomes with LV-only fCRTp [22,23,24,26,28,29].