The effects of high-degree AV block requiring chronic ventricular pacing after tricuspid valve surgery in patients with a systemic right ventricle
Authors: Nederend M , Jongbloed MRM , Kies P , Vliegen HW , Bouma BJ , Regeer MV , Koolbergen DR , Hazekamp MG , Schalij MJ , Egorova AD 
Published: May 2022

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background
Patients with transposition of the great arteries(TGA) after atrial switch or congenitally corrected TGA(ccTGA) are prone to systemic right ventricular(sRV) failure. Atrioventricular(AV)-conduction disturbances requiring chronic ventricular pacing and tricuspid valve(TV) regurgitation aggravate sRV dysfunction. Timely TV surgery stabilizes sRV function, yet is a risk factor for AV-block, potentially contributing to sRV failure due to pacing-induced dyssynchrony. The aim of this study is to explore the incidence, timing and functional consequences of AV-block requiring ventricular pacing after TV surgery in sRV patients.

Methods
Consecutive adolescent and adult patients with a sRV who underwent TV surgery in the period 1989-2020 and follow-up at our centre were included in this observational cohort study. Demographic and clinical data was collected from patient records.

Results
Data of 28 patients(54% female, 57% ccTGA, mean age at surgery 38±13 years) was analysed. Mean follow-up duration was 9.7±6.8 years. Five patients(18%) already had chronic(&gt;40%) subpulmonary left ventricular pacing preoperatively, of which 2 received cardiac resynchronization therapy(CRT) upgrade prior to surgery. One patient received CRT during TV surgery. Of the remaining 22 patients at risk for AV-block after surgery, 9(41%) developed an indication for chronic pacing during follow-up, of which 3(33%) before hospital discharge and a total of 5(56%) within 24 months postoperatively, Figure 1. Five(20%) patients received CRT during follow-up due to progressive heart failure(HF). In one patient with transvenous upgrade, effective resynchronization was not attained due to suboptimal lead position. Of the patients receiving chronic pacing, 9(75%) died, underwent ventricular assist device(VAD) implantation or required CRT due to progressive HF. Only 4(31%) patients with native AV-conduction reached this composite endpoint(p=0.027). QRS duration, a surrogate marker for dyssynchrony, was significantly higher in patients with chronic pacing than with native AV-conduction(217±24 vs 116±23msec, p=0.000), as was NT-pro-BNP(2746[1242–6879] vs 495[355–690]ng/L, p=0.004) and the percentage of patients with ≥1 class of deterioration of systolic sRV function(p=0.001), Figure 2.

Conclusions
Patients with a failing sRV who undergo TV surgery are prone to AV-conduction abnormalities with 41% developing an indication for chronic ventricular pacing during follow-up. The patient group with chronic pacing has significantly more events of the composite endpoint of death, VAD implantation or upgrade to CRT, higher percentage of ≥1 grade deterioration of systolic sRV function and higher levels of HF biomarker NT-pro-BNP. Implantation of an epicardial sRV lead at the time of TV surgery for future CRT may be considered to attenuate the detrimental effects of subpulmonary ventricular pacing in this HF prone patient group with complex anatomy that limits transvenous possibilities.