The impact of right ventricular size and function on long-term outcomes in patients undergoing cardiac resynchronization therapy
Authors: Galloo X , Stassen J , Hirasawa K , Mertens B J A , Cosyns B , Van Der Bijl P , Delgado V , Ajmone Marsan N , Bax J J 
Published: October 2022

Abstract

Background
Right ventricular (RV) adverse remodelling is a complex process, consisting of progressive RV dilatation and RV systolic dysfunction. Both parameters individually are important prognostic markers in patients receiving cardiac resynchronization therapy (CRT). The prognostic value of assessing both parameters into one model has not been evaluated.

Purpose
The current study evaluated RV size and RV systolic function prior to CRT implantation and their association with outcome.

Methods
Patients who underwent CRT implantation and had echocardiographic data on RV size (assessed by indexed RV end-diastolic area [RVEDAi], using sex-specific cut-off values to define RV dilatation: RVEDAi &gt;12.6 cm2/m2 for men and RVEDAi &gt;11.5 cm2/m2 for women) and RV systolic function (measured by tricuspid annular plane systolic excursion [TAPSE], with TAPSE &lt;17 mm considered RV dysfunction) before implantation, were included in the present analysis. The primary end-point was all-cause mortality. The incremental prognostic value of RV size and RV systolic function was assessed by likelihood-ratio testing evaluating the change in global chi-square values.

Results
A total of 773 patients (mean age 66±10 years, 75% males) were included in the current analysis, of which 509 patients (66%) had RV dilatation and/or dysfunction, with respectively 253 patients (33%) and 408 patients (53%) showing RV dilatation or RV systolic dysfunction. The cumulative survival rates for the overall population were 97%, 91% and 72% at 1-, 2- and 5-years, respectively. Five-year survival was significantly better in patients with normal RV size compared to patients with RV dilatation (log-rank p&lt;0.001). Similarly, patients with normal RV systolic function had significantly better five-year survival, compared to patients with reduced RV systolic function (log-rank p&lt;0.001). Multivariable Cox regression analysis for all-cause mortality showed that RV size and RV systolic function, assessed as continuous as well as categorical variables, were independently associated with all-cause mortality both individually and in combination (Figure 1). Larger RV size was associated with worse all-cause mortality, whereas better RV systolic function was associated with better all-cause mortality at 5-years follow-up. In addition, the evaluation of RV size plus RV function provided incremental prognostic value over the evaluation of RV size or RV function alone (likelihood-ratio test p&lt;0.005 for all models; Figure 2).

Conclusions
Patients receiving CRT often present with RV dilatation and/or dysfunction, which are associated with significantly worse survival, compared to patients with normal RV size and function. Prognostic assessment in CRT recipients should include both RV size and function, since the combination of both parameters provides incremental prognostic value to assess all-cause mortality.

Funding Acknowledgement
Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Society of Cardiology (ESC)