Adverse impact of chronic subpulmonary left ventricular pacing on systemic right ventricular function in patients with congenitally corrected transposition of the great arteries Wee Tiong Yeo a,b,1 , Julian W.E. Jarman a,1 , Wei Li a,1 , Michael A. Gatzoulis a,1 , Tom Wong a, ⁎ ,1 a Royal Brompton & Harefield NHS Foundation Trust and Imperial College London, United Kingdom b National University Heart Centre, Singapore abstract article info Article history: Received 1 September 2013 Accepted 30 November 2013 Available online 7 December 2013 Keywords: Congenitally corrected transposition of the great arteries Cardiac pacing Congenital heart disease Cardiac resynchronization Background: Patients with congenitally corrected transposition of the great arteries (ccTGA) are at high risk of heart block requiring subpulmonary left ventricular (LV) pacing. Long-term right ventricular (RV) pacing in congenitally normal hearts is associated with LV dysfunction. We examined the effects of univentricular subpulmonary LV pacing on the systemic RV in a ccTGA cohort. Methods: ccTGA patients with two echocardiographic studies at least 6 months apart were included. Records of 52 patients, 22 with pacing, were retrospectively reviewed. Seven patients with biventricular pacing were included for comparison. Results: The LV-Paced Group experienced deterioration in the RV fractional area change (RVFAC) (28.7 ± 10.0 vs. 21.9 ± 9.1%; P = 0.003), systemic atrioventricular valve regurgitation (P = 0.019) and RV dilatation (end- diastolic area 32.7 ± 8.7 vs. 37.2 ± 9.0 cm 2 ; P = 0.004). There was a corresponding deterioration in NYHA class (P = 0.013). Multivariate Cox regression analysis showed that pacing was an independent predictor of deteriorating RV function and RV dilation (hazard ratio 2.7(10–7.0) and 4.7(1.1–20.6) respectively). None of these parameters changed significantly in the Un-paced Group. The CRT Group showed improvement in RVFAC (22.0% to 30.7% (P = 0.030) and NYHA class (P = 0.030), despite having lower baseline RVFAC (22.0 ± 5.7 vs. 31 ± 9.7%; P = 0.025) and greater dyssynchrony (RV total isovolumic time 13.4 ± 2.1 vs. 9.3 ± 4.2 s/min; P = 0.016) when compared to the Un-Paced Group. Conclusions: Univentricular subpulmonary LV pacing in patients with ccTGA predicted deterioration in RV func- tion and RV dilatation over time associated with deteriorating NYHA class. Alternative primary pacing strategies such as biventricular pacing may need consideration in this vulnerable group already highly prone to mortality from systemic RV failure. © 2013 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Congenitally corrected transposition of the great arteries (ccTGA) is a structural congenital heart defect in which life expectancy is usually determined by development of progressive heart failure from deterio- rating function of the systemic right ventricle (RV) [1]. The condition has a high incidence of heart block, thought to relate to anterior displacement of the atrioventricular (AV) node altering its functional properties [2,3]. The prevalence of heart block reaches 10% to 15% by adolescence, and 30% in early–mid adulthood [4]. Epicardial or endocardial pacing of the subpulmonary left ventricle (LV) has been the mainstay of treatment. Extensive evidence exists that RV pacing in structurally normal hearts leads to deleterious effects on LV function [5,6]. However, the effects of subpulmonary LV pacing on the systemic RV in ccTGA have not been well examined. Potential sequential changes in systemic RV size and function related to LV pacing in these patients have not been reported. We tested the hypothesis that systemic RV function declines in patients with ccTGA who received univentricular subpulmonary LV pacing when compared with a control group of ccTGA patients who had no pacing over a similar period. 2. Methods We identified all adult patients with ccTGA in our institutional database. Clinical, echocardiographic and pacing data were carefully evaluated retrospectively. Patients were categorized into two principal groups for comparison: an “LV-Paced Group” with univentricular subpulmonary LV pacing and an “Un-paced Group” without pacing. In addition, we examined a third group of patients with cardiac resynchronization therapy (CRT) in whom both ventricles were paced: the “CRT Group”. International Journal of Cardiology 171 (2014) 184–191 ⁎ Corresponding author at: Heart Rhythm Centre, NIHR Cardiovascular Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust Sydney Street, London, SW3 6NP, United Kingdom. Tel.: +44 20 7351 8619; fax: +44 20 7351 8629. E-mail address: tom.wong@imperial.ac.uk (T. Wong). 1 This author takes responsibility for all aspects of the reliability and freedom from bias of the data presented and their discussed interpretation. 0167-5273/$ – see front matter © 2013 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijcard.2013.11.128 Contents lists available at ScienceDirect International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard