Abstracts

Rationale: Evaluation of brain metabolism by MRS can be useful in predicting the risk for poor neuropsychological outcomes. Follow-up studies on heart transplant recipients were previously done up to 3 years post-transplant. In this study, neuropsychological testing will be done in patients about 12 months to 15 years post-transplant, a period when these children have achieved maximum recovery. Our goal is to examine the prognostic value of MRS and clinical data such as presence of seizures in determining long-term outcome.Methods: Pediatric patients who underwent cardiac transplantation at Loma Linda University (LLU) Children's Hospital from 1999- 2014 and those who had MRS pre-transplant were included in the study. Pediatric Cerebral Performance Category Scale (PCPCS) scores were determined at the most recent follow-up visit and neuropsychological evaluations were done on patients who consented to testing. Single voxel MRS in mid-occipital gray matter was used to evaluate N-acetylaspartate (NAA), creatine (Cre), choline (CHO) , myo-inositol (Ins), and lactate (Lac). Metabolite ratios (NAA/Cre, NAA/ Cho, Cho/Cre, Ins/Cre) and the presence of lactate were calculated. MRS findings were correlated with the presence of seizures pre and post- transplant. The neurologic outcome was dichotomized into poor (moderate, severe disabilities, vegetative state, or death) vs good (normal, mild disabilities) for statistical analyses.Results: We reviewed the records of 24 patients and compared their MRS findings to age-matched controls. The presence of lactate in the occipital gray matter correlated with poor outcomes (Chi square,p=0.042). The presence of lactate also correlates with a higher PCPCS score (p=0.009). Seizures correlate with a higher PCPCS scores (p=.025). Compared to 4/18 of the good outcome group (n=18) who had seizures, 5/6 of the poor outcome group (n=6) had seizures, p= .007. Out of the 9 patients who had seizures, lactate was present in 4/9. The presence of lactate and seizures, either pre-transplant or post-transplant, have a significant association with each other (Pearson, p=.027) despite the absence of a temporal relationship between the MRS and the seizures. Neuropsychological evaluations were done on 11 of the 21 patients who consented to testing. One out of 11 had seizures and her neuropsychological profile was poor compared to an age-matched control.Conclusions: The presence of lactate in MRS and/or the presence of seizures pre or post heart transplant significantly correlated with poor long-term outcomes. The metabolite ratios (NAA/Cre, NAA/ Cho, Cho/Cre, Ins/Cre) were not significantly correlated with outcomes. The poor neuropsychological profile of a patient who had seizures supports the idea that the presence of seizures can give us a clue on the extent of brain injury from the congenital heart disease or the surgery itself. MRS Imaging when performed prior to heart transplant along with clinical data such as the presence of seizures may help determine long-term prognosis.