Right ventricular systolic dysfunction but not dilatation correlates with prognostically significant reductions in exercise capacity in repaired Tetralogy of Fallot

Abstract

Aims The optimal timing for pulmonary valve replacement in asymptomatic patients with repaired Tetralogy of Fallot (rTOF) and pulmonary regurgitation remains uncertain but is often guided by increases in right ventricular (RV) end-diastolic volume. As cardiopulmonary exercise testing (CPET) performance is a strong prognostic indicator, we assessed which cardiovascular magnetic resonance (CMR) parameters correlate with reductions in exercise capacity to potentially improve identification of high-risk patients. Methods and results In all, 163 patients with rTOF (mean age 24.5 ± 10.2 years) who had previously undergone CMR and standardized CPET protocols were included. The indexed right and left ventricular end-diastolic volumes (RVEDVi, LVEDVi), right and left ventricular ejection fractions (RVEF, LVEF), indexed RV stroke volume (RVSVi), and pulmonary regurgitant fraction (PRF) were quantified by CMR and correlated with CPET-determined peak oxygen consumption (VO2) or peak work. On univariable analysis, there was no significant correlation between RVEDVi and PRF with peak VO2 or peak work (% Jones-predicted). In contrast, RVEF and RVSVi had significant correlations with both peak VO2 and peak work that remained significant on multivariable analysis. For a previously established prognostic peak VO2 threshold of <27 mL/kg/min, receiver-operating characteristic curve analysis demonstrated a Harrell’s c of 0.70 for RVEF (95% confidence interval 0.61–0.79) with a sensitivity of 88% for RVEF <40%. Conclusion In rTOF, CMR indices of RV systolic function are better predictors of CPET performance than RV size. An RVEF <40% may be useful to identify prognostically significant reductions in exercise capacity in patients with varying degrees of RV dilatation.

Ventricular flow analysis and its association with exertional capacity in repaired tetralogy of Fallot: 4D flow cardiovascular magnetic resonance study

“…Cardiopulmonary exercise testing (CPET) offers additional prognostic guidance for timing of intervention [ 8 ] but is not routinely performed in the asymptomatic or mildly symptomatic patient. In a retrospective analysis for rTOF patients with both CMR and CPET, RV ejection fraction (RVEF) < 40% but neither RV end-diastolic volume (EDV) nor end-systolic volume (ESV) was predictive of peak oxygen uptake (VO 2 ) below the established prognostic threshold of 27 ml/kg/min [ 9 ]. As severe RV dysfunction presents late, its diagnostic utility for incipient exercise intolerance is limited.…”

Cardiopulmonary Exercise Testing in Repaired Tetralogy of Fallot: Multiparametric Overview and Correlation with Cardiac Magnetic Resonance and Physical Activity Level

“…Babu-Narayan et al showed that in rToF patients undergoing PVR, preoperative oxygen uptake was indeed predictive of early postoperative mortality [16]. However, the relationship between RV dilatation and/or dysfunction and some CPET parameters is still poorly understood [17,18]. In addition, its potential usefulness as a tool for risk stratification and patient selection in asymptomatic adolescents and adults with rToF remains unclear.…”

Moving beyond size: vorticity and energy loss are correlated with right ventricular dysfunction and exercise intolerance in repaired Tetralogy of Fallot

“…Furthermore, the interaction between PR and tricuspid inflow potentially limits augmentation of RV cardiac output during exercise, leading to exercise intolerance. Previous CMR studies have not demonstrated any significant correlation between RV size and PR with exercise capacity [ 8 , 9 , 11 ], informing the use of modified parameters such as ventricular global function index [ 9 ]. Thus far, only right ventricular systolic dysfunction and branch pulmonary artery size discrepancy have correlated with decreased exercise capacity [ 7 , 11 , 51 ].…”

“…Previous CMR studies have not demonstrated any significant correlation between RV size and PR with exercise capacity [ 8 , 9 , 11 ], informing the use of modified parameters such as ventricular global function index [ 9 ]. Thus far, only right ventricular systolic dysfunction and branch pulmonary artery size discrepancy have correlated with decreased exercise capacity [ 7 , 11 , 51 ]. In our subgroup cohort, RVOT-VQ and RVOT-EQ correlated with VO 2-max and % predicted VO 2-max , suggesting that the abnormal intracardiac flow patterns from PR is still the link to exercise intolerance in rTOF patients.…”

“…However, current guidelines acknowledge the limitations of these conventional CMR measurements [2,3], as they do not necessarily predict deterioration of the RV [4], nor do they incorporate the diversity of RV morphology, RV motion, and RV outflow tract (RVOT) geometry [5][6][7]. Exclusive interpretation of the RV in rTOF using indexed RV end-diastolic volume (RVEDVI), indexed RV endsystolic volume (RVESVI), RV ejection fraction (RVEF) and pulmonary regurgitant fraction (PR%) does not fully describe RV dysfunction, nor correlate with exercise intolerance [8][9][10][11]. Furthermore, the direct link between PR, RV dysfunction and exercise intolerance has not been clarified, as the resultant intracardiac flow abnormalities from PR have not been comprehensively studied in rTOF patients.…”