Noninvasive Assessment of Right Ventricular-Pulmonary Arterial Coupling in Repaired Tetralogy of Fallot by Magnetic Resonance Imaging.

Abstracts No Comments

Mets G; Hospital for Sick Children Toronto Ontario Canada.
Bitterman Y; Mercer-Rosa L; Wald R; Friedberg MK

Journal of the American Heart Association. 14(23):e042371, 2025 Dec 02.

BACKGROUND: Right ventricular (RV) to pulmonary arterial coupling (RVPAc)
quantifies RV contractility in relation to its afterload but traditionally
requires high-fidelity catheter derived pressure-volume loops. We sought
to evaluate a noninvasive volume-based RVPAc parameter in children and
adults with repaired tetralogy of Fallot in relation to pulmonary
regurgitation (PR), RV outflow tract obstruction (RVOTO), and exercise
capacity.

METHODS: We retrospectively studied 92 pediatric and 105 adult patients
with repaired tetralogy of Fallot who had cardiovascular magnetic
resonance imaging and cardiopulmonary exercise testing within a 1-year
interval. RVPAc was calculated as the ratio of RV end-systolic volume over
stroke volume. RVOTO gradient was obtained by echocardiography; RV
ejection fraction, and PR fraction by cardiovascular magnetic resonance
imaging. Exercise capacity was measured as the percentage of predicted
peak oxygen consumption during cardiopulmonary exercise testing. Subgroups
were established depending on the combination of PR-RVOTO (cutoff defined
as PR >30% and RVOTO >25 mm Hg).

RESULTS: RVPAc was significantly higher in adult versus pediatric
patients (1.23 [1.03-1.48] versus 1.00 [0.88-1.15]; P<0.001). RVPAc was
comparable in the 4 pediatric hemodynamic subgroups (P=0.38) but tended to
be higher in adults with either RVOTO, PR, or RVOTO+PR (P=0.05). RVPAc
highly correlated with RVEF (r=-0.991, P<0.001) but was not associated
with percentage of predicted peak oxygen consumption.

CONCLUSIONS: Worse RVPAc in adult versus pediatric patients with repaired
tetralogy of Fallot may signify progressive RV-PA uncoupling with age- or
era-related effects. However, the clinical use of volumetric RVPAc in
repaired tetralogy of Fallot appears limited, as it does not provide
additional information over RVEF and is not associated with exercise
capacity.