Purpose: In light of the major impact of cardiovascular morbidity on long-term transplant outcomes, a prospective controlled study was conducted to investigate changes in myocardial function and strain in pediatric kidney transplant (Tx) recipients over time.

Methods: Kidney Tx recipients (3-20 yrs) had standard echocardiographic measures of left ventricular size and function and longitudinal and circumferential strain and strain rate measured using speckle tracking (ST) at 1, 18 and 30 months post-Tx. ST determines strain by measuring change in distance between 2 acoustic speckles during myocardial contraction, and strain rate is strain per second. More negative strain signifies better contractility. Fasting glucose, lipids, HbA1c%, waist circumference and blood pressure were measured at each time point. Tx with metabolic syndrome (MS) met ≥ 3 of the following: HbA1c%>5.6 or glucose>100, BP>90th %, obesity (waist ≥95th%), HDL <5th %, TG > 95th %. Healthy, lean, normotensive children served as controls. Student's t-test was used to compare standard parameters between groups.

Results: Study group consisted of 31 pediatric kidney Tx recipients (54.8% African American (AA), age 13.1±0.75 years. Controls were 24 healthy children (62.5% AA) of similar age (11.4+0.14 years, p=0.14). LVM/Ht^2.7 and E/E' (indicator of diastolic function) of Tx were worse vs. controls (40.3±0.4 vs. 29.1±1.5, p=0.05 and 8.6 vs. 6.8, p=0.001). Tx with obesity had lower ejection fraction vs. lean Tx (62.9±0.7 vs. 65.1±0.4, p=0.02). LVM/Ht^2.7 was greater in Tx with vs. without MS (46.7±5.2 vs. 33.1±2.0, p=0.005). ST analysis showed that Tx had worse longitudinal strain but superior circumferential strain vs. controls (-19.9±0.4 vs. -23.1±0.4, p=0.00 and -25.5±0.5 vs. -23.9±0.4, p=0.01). Tx with AA race, obesity, hypertension, and MS had worse longitudinal strain vs. Tx who were non- AA, lean, normotensive and without MS, respectively (-19.2+0.3 vs. -21.0+0.4, p=0.00, -20.6±0.3 vs. -18.6±0.4, p=0.001, -19.6±0.3 vs. -20.8±0.5, p=0.03, and -19.0±0.5 vs. -20.3±0.3, p=0.03). Neither standard echo nor strain parameters improved over time post-Tx.

Conclusions: Pediatric kidney Tx recipients have impaired myocardial function, characterized by increased LVM/Ht^2.7 , decreased E/E', and impaired longitudinal strain with compensatory improvement in circumferential strain. Myocardial function after Tx is negatively impacted by AA ethnicity, obesity, hypertension, and MS. Myocardial function does not change significantly during the first 30 months post-tx.

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