Cardiac MRI predictors of adverse outcomes in adults with a systemic right ventricle

Cardiac MRI predictors of adverse outcomes in adults with a systemic right ventricle.

Lewis MJ, Van Dissel A, Kochav J, DiLorenzo MP, Ginns J, Zemer-Wassercug N, Groenink M, Mulder B, Rosenbaum M.ESC Heart Fail. 2022 Apr;9(2):834-841. doi: 10.1002/ehf2.13745. Epub 2022 Jan 20.PMID: 35048545

 

Take Home Points:

1. Cardiac MRI parameters may be used to predict increased risk of death, heart transplantation, or the need for a ventricular assist device in patients with a systemic right ventricle in biventricular physiology.
2. A cut-off value of 130ml/m² may be used to predict good survival outcomes.

Commentary from Dr. MC Leong (Kuala Lumpur), section editor of ACHD Journal Watch:

The systemic right ventricles (SRV) are inherently not meant for system circulation and will eventually fail. Assessing patients with SRV has been challenging, especially in identifying those who will fail early and require a heart transplant. Various methods have been advocated, such as (a) assessing the SRV function [1], (b) identifying myocardial fibrosis [2], and (c) assessing the left ventricular function [3]. This study looked at a novel way of assessing the SRV – by assessing the right ventricular dimension.

 

The study is a retrospective study, studying 158 patients from two centres with SRV and biventricular physiology i.e. congenitally corrected transposition of the great arteries (ccTGA) and transposition of the great arteries post atrial switch operation (DTGA). The right ventricular dimensions were acquired through magnetic resonance (MR) via conventional methods, and the right ventricular mass was calculated by including the interventricular septum. The MR-derived parameters were compared to the primary outcomes: a composite of death, heart transplantation referral, or destination therapy with a ventricular assist device. Table 1 shows the baseline characteristics of the cohort of patients. By and large, patients with ccTGA had a larger indexed right ventricular end-systolic volume, stroke volume, and a higher rate of primary outcomes.

 

 

 21 patients (13%) met the primary endpoint over a cumulative follow-up of 1320 patient-years (median duration of follow-up: 8.5 years). 15 deaths (71%), 4 referrals for a heart transplant (20%), and 2 (10%) patients underwent destination VAD placement. The cause of death included 9 from progressive heart failure, 3 from sudden cardiac death, and 3 with an unknown cause. Univariable and multivariable predictors of the primary outcomes are tabulated in Table 2. Receiver operating curve analyses were performed to obtain cut-off values for predicting primary endpoints (Table 3). 

 

 

 

For DTGA and ccTGA patients with ≥ moderate tricuspid valve regurgitation, the optimal cut-point of RVEDVI was higher when compared with patients with < moderate tricuspid valve regurgitation (DTGA: 141 vs.130 mL/m2; ccTGA: 131 vs. 124 mL/m2). However, for simplicity’s sake, a cut-off value of 130ml/m2 was used and the value showed good survival estimates for both groups (Figures 1 & 2). 

 

 

 

The emergence of multiple parameters to assess the systemic right ventricle proves that examining the SRV using a single parameter may yield inconsistent results. One such example is the right ventricular function. Many, if not all, of these patients, have varying degrees of tricuspid regurgitation. The degree of tricuspid valve regurgitation affects the accurate calculation of the systolic function of the right ventricle. The ventricular stroke volume contributes to tricuspid valve regurgitation and the true cardiac output. The ventricular function is often overestimated, especially in the presence of severe tricuspid regurgitation. Moving forward, should we be looking at a composite of parameters instead a single one?

 

References:

1. Rutledge JM, Nihill MR, Fraser CD, Smith OE, McMahon CJ, Bezold LI. Outcome of 121 patients with congenitally corrected transposition of the great arteries. Pediatr Cardiol. 2002 Mar-Apr;23(2):137-45.
2. Broberg CS, Valente AM, Huang J, Burchill LJ, Holt J, Van Woerkom R, Powell AJ, Pantely GA, Jerosch-Herold M. Myocardial fibrosis and its relation to adverse outcome in transposition of the great arteries with a systemic right ventricle. Int J Cardiol. 2018 Nov 15;271:60-65. 
3. Surkova E, Segura T, Dimopoulos K, Bispo D, Flick C, West C, Babu-Narayan SV, Senior R, Gatzoulis MA, Li W. Systolic dysfunction of the subpulmonary left ventricle is associated with the severity of heart failure in patients with a systemic right ventricle. Int J Cardiol. 2021 Feb 1;324:66-71.