Tucker S; Texas Children’s Hospital, Houston, TX, USA.
Wang A; Griffith G; Ward K; Desai L;et al

Pediatric Cardiology. 47(8):3287-3294, 2026 Dec.

Multiparametric cardiac magnetic resonance (CMR) is increasingly used for
rejection and coronary artery vasculopathy (CAV) surveillance in pediatric
heart transplant recipients (PHTR). There is limited data regarding how
graft assessment by multiparametric CMR may reflect functional capacity in
PHTR. To explore the relationship between multiparametric CMR and markers
of exercise capacity in PHTR. PHTR who underwent CMR within 1 year of
cardiopulmonary exercise testing (CPET) were retrospectively reviewed.
Those with submaximal effort on CPET (respiratory exchange ratio < 1.10),
depressed function (left ventricular ejection fraction (LVEF) < 50% and/or
right ventricular ejection fraction (RVEF) < 45%), or significant clinical
events (rejection, new or worsening CAV, cardiac hospitalizations) between
CMR and CPET were excluded. CMR variables included biventricular volumes,
ejection fraction, cardiac index (CI), myocardial T2, T1/extracellular
volume fraction (ECV), and myocardial perfusion reserve index (MPRI). CPET
variables were VO2peak, O2 pulse, percent age-predicted maximum heart rate
(APMHR), HR reserve, and exercise duration. Relationships between
variables were studied using correlations and regression. Forty-seven PHTR
were included. Time between CPET and CMR was 5.5 +/- 3.4 months. CI
correlated positively with O2 pulse (R = 0.642, p < 0.001). Global T1
correlated negatively with both APMHR (R = – 0.538, p < 0.001) and HR
reserve (R = – 0.598, p < 0.001). Global T2 correlated negatively with
APMHR (R = – 0.335, p = 0.049), HR reserve (R = – 0.488, p = 0.003), and
VO2peak (R = – 0.327, p = 0.045). In PHTR with normal LV function,
CMR-derived tissue characteristics have correlations with exercise
capacity. Larger studies are needed to understand the role of
multiparametric CMR in the functional surveillance of PHTR.