Effectiveness of conduction system pacing for cardiac resynchronization therapy: A systematic review and network
Hamed Tavolinejad1, Sina Kazemian1, Ali Bozorgi1
1Department of Cardiac Electrophysiology, Tehran Heart Center, Cardiovascular Diseases Research Institute, Tehran University of Medical Sciences, Tehran, Iran.
Insights
Conduction system pacing cardiac resynchronization therapy (CSP-CRT), including His pacing (His-CRT) and left bundle branch pacing (LBB-CRT), offers improved outcomes over biventricular CRT. LBB-CRT shows particular promise with lower pacing thresholds and high success rates.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Devices
Background:
- Biventricular cardiac resynchronization therapy (BiV-CRT) is ineffective in about one-third of patients, necessitating alternative pacing strategies.
- Conduction system pacing (CSP-CRT) aims to improve cardiac synchronization by pacing the heart's native conduction system.
Approach:
- A systematic literature review and meta-analysis compared His pacing (His-CRT) and left bundle branch pacing (LBB-CRT) against BiV-CRT.
- Data from 37 publications, including 20 comparative studies, were analyzed for efficacy, QRS duration, ejection fraction, and clinical outcomes.
Key Points:
- Both His-CRT and LBB-CRT demonstrated greater improvements in QRS duration, left ventricular ejection fraction, and New York Heart Association class compared to BiV-CRT.
- LBB-CRT exhibited higher success rates (91.5%) and lower pacing thresholds than His-CRT (73.5%) and BiV-CRT.
- CSP-CRT was associated with reduced mortality and hospitalization risks.
Conclusions:
- CSP-CRT, particularly LBB-CRT, offers significant advantages over BiV-CRT in terms of electrical and clinical synchronization.
- LBB-CRT presents a promising alternative due to its high efficacy and favorable pacing parameters.
- Further randomized trials are warranted to definitively establish the long-term efficacy of CSP-CRT.
Introduction:
Cardiac resynchronization therapy (CRT) with biventricular pacing (BiV-CRT) is ineffective in approximately one-third of patients. CRT with Conduction system pacing (CSP-CRT) may achieve greater synchronization. We aimed to assess the effectiveness of CRT with His pacing (His-CRT) or left bundle branch pacing (LBB-CRT) in lieu of biventricular CRT.
Methods And Results:
The PubMed, Embase, Web of Science, Scopus, and the Cochrane Library were systematically searched until August 19, 2023, for original studies including patients with reduced left ventricular ejection fraction (LVEF) who received His- or LBB-CRT, that reported either CSP-CRT success, LVEF, QRS duration (QRSd), or New York Heart Association (NYHA) classification. Effect measures were compared with frequentist network meta-analysis. Thirty-seven publications, including 20 comparative studies, were included. Success rates were 73.5% (95% CI: 61.2-83.0) for His-CRT and 91.5% (95% CI: 88.0-94.1) for LBB-CRT. Compared to BiV-CRT, greater improvements were observed for LVEF (mean difference [MD] for His-CRT +3.4%; 95% CI [1.0; 5.7], and LBB-CRT: +4.4%; [2.5; 6.2]), LV end-systolic volume (His-CRT:17.2mL [29.7; 4.8]; LBB-CRT:15.3mL [28.3; 2.2]), QRSd (His-CRT: -17.1ms [-25.0; -9.2]; LBB-CRT: -17.4ms [-23.2; -11.6]), and NYHA (Standardized MD [SMD]: His-CRT:0.4 [0.8; 0.1]; LBB-CRT:0.4 [-0.7; -0.2]). Pacing thresholds at baseline and follow-up were significantly lower with LBB-CRT versus both His-CRT and BiV-CRT. CSP-CRT was associated with reduced mortality (R = 0.75 [0.61-0.91]) and hospitalizations risk (RR = 0.63 [0.42-0.96]).
Conclusion:
This study found that CSP-CRT is associated with greater improvements in QRSd, echocardiographic, and clinical response. LBB-CRT was associated with lower pacing thresholds. Future randomized trials are needed to determine CSP-CRT efficacy.
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