Exercise stress echocardiography for the assessment of right ventricular contractile reserve in repaired tetralogy of fallot

Abstract Background Previous studies have shown that patients with repaired Tetralogy of Fallot (rTOF) have reduced right ventricular contractile reserve (RVCR) in response to exercise. However, the extent of this reduced RVCR in patients who meet the surgical indications for pulmonary valve replacement (PVR) remains unclear. Purpose We investigated how PVR criteria relate to right ventricular (RV) responsiveness to exercise in adults with rTOF, by measuring right ventricular free wall strain (RVFWS) at rest (Rest-RVFWS) and during peak stress (Peak-RVFWS). Methods Forty-five rTOF patients (46.7% women) and 12 healthy subjects (Control group, 50% women) were included. Exercise stress echocardiography was conducted using a semi-recumbent cycle ergometer with a ramp protocol. Left ventricular and RV parameters were measured at rest and peak exercise. RVFWS, a parameter for assessing right ventricular systolic function, was derived through offline analysis from RV-focused views at each stage. Patients with rTOF were further divided into two groups: those who met the PVR criteria and/or were scheduled for PVR or TPVI (Indicated group, I-group; 22 patients) and those who did not (Observation group, O-group; 23 patients). Results The baseline characteristics for each group (I-group, O-group, and Control) are presented in Figure 1. The O-group had significantly better demographics in terms of age, BNP, QRS duration, MRI RV ejection fraction, RV end-diastolic volume index, RV end-systolic volume index, and pulmonary regurgitation (PR) fraction compared with the I-group. Figure 2A illustrates the change in RVFWS in response to exercise for each group. A significant increase in RVFWS with exercise was observed in the Control group (rest RVFWS 24.1±5.5%, peak RVFWS 31.0±4.1%, p0.001). No significant difference in RVFWS at rest was identified between the rTOF groups (Rest RVFWS: I-group 19.3±4.0% vs O-group 21.7±6.0%, p=0.379). During exercise, RVFWS did not increase in the I-group, whereas in the O-group, RVFWS did increase with exercise (peak RVFWS: I-group 20.0±7.1% vs O-group 25.4±7.4%, p=0.033). In the O-group, 5 out of 23 patients with significant PR (PR fraction 30%) had a peak RVFWS below 20% during peak exercise and showed a decline in RVFWS during exercise (Figure 2B). Conclusion Patients with repaired Tetralogy of Fallot (rTOF) showed a diminished RVCR, with a more pronounced reduction observed in the I-group. Approximately 20% of patients in the O-group, who exhibit significant PR and reduced RVCR, may require early intervention to prevent the progression of further myocardial damage caused by PR. Current PVR criteria mainly focus on right ventricular size, which may not fully identify patients with impaired RVCR. Assessment of RVCR to exercise using RVFWS may offer additional supplementary information to the conventional PVR criteria.