Longitudinal right ventricular function is a better predictor of right ventricular contribution to exercise performance than global or outflow tract ejection fraction in tetralogy of Fallot: a combined echocardiography and magnetic resonance study.

AIMS: The contribution of the systolic function of the right ventricular (RV) outflow tract (RVOT) and of longitudinal shortening of the body of the right ventricle to global RV systolic function and exercise capacity in patients after tetralogy of Fallot (TOF) repair is unclear. Our aim was to characterize the functional role of the RVOT and to identify the most suitable method of assessing RV systolic function in clinical practice.

METHODS: The cardiac magnetic resonance (CMR) studies, echocardiograms, and medical records of 50 consecutive patients with repaired TOF who underwent CMR were reviewed. The volumes of the RVOT and of the remainder of the RV were measured separately. Echocardiographic RV strain measurements based on ultrasound speckle tracking were collected.

RESULTS: After excluding the akinetic RVOT, RVEF was statistically higher (47.1 vs. 45.0%, P< 0.0001) but the average increase in EF was small. The correlations of fractional area change and global longitudinal strain, both by echocardiography, with global RVEF were moderate (r= 0.59, P= 0.0001 and r= 0.56, P= 0.0004, respectively). The correlation between RVEF and predicted maximal oxygen consumption (VO(2)max-predicted) was weak, regardless of whether the akinetic RVOT was included or not (r= 0.33, P= 0.049 and r= 0.36, P= 0.03, respectively). Of all imaging parameters, echocardiographic RV longitudinal strain correlated best with VO(2)max-predicted (r= 0.66, P= 0.0001).

CONCLUSIONS: In patients following TOF repair, echocardiographic and CMR descriptors of global RV systolic function are, at best, weak predictors of exercise tolerance. Longitudinal function of the RV, measured remotely from the RVOT, may be a more important determinant of exercise performance than global RVEF in patients with aneurismal RVOTs.