Inter-Rater Reliability of Total Cardiac Volume Measurement for Heart Transplantation: An ACTION Collaborative Study

Abstract

<h3>Purpose</h3> There is increasing evidence that size-matching pediatric donor hearts by direct measurement of total cardiac volume (TCV) is superior to traditional methods based on body size. Currently, there are no standardized protocols for assessing TCV or studies evaluating the inter-rater reliability of such measurements, both critical requirements to support a national TCV-based size-matching system. We sought to evaluate the inter-rater reliability of a standardized TCV measurement protocol across multiple pediatric transplant centers. <h3>Methods</h3> A total of nine pediatric transplant centers within the Advanced Cardiac Therapies Improving Outcomes Network (ACTION) performed TCV assessments in 12 test subjects. TCV was assessed from computed tomography (CT) or magnetic resonance imaging (MRI) files using a standard TCV measurement protocol that was reviewed with each center. Interclass correlation coefficients (ICC) were calculated between all centers and each center in relation to the primary center. <h3>Results</h3> Of the 12 test subjects, the median age was 9.5 years (range 18 days to 30 years), the median weight was 28 (2.5 to 89) kg; 3 had no heart disease (donors), 3 had cardiomyopathy (CMP); 6 had congenital heart disease (CHD) including 4 single-ventricle CHD (1 shunted newborn, 2 Glenns, and 2 Fontans) and 2 biventricular CHD (aortic stenosis, tetralogy of Fallot/pulmonary atresia). Imaging modalities included 7 contrast CTs (CCT), 3 non-contrast CT (NCT), and 2 MRI. TCV was performed by 7 cardiologists, 1 radiologists, and 1 biomedical engineer. Overall compared to the primary center, the ICC across all 8 centers for all 12 scans was 0.99 (95% CI 0.98-0.99), including in normal hearts 0.98 (0.95-1.0), in CMP 0.99 (0.96-1.0), in CHD 0.99 (95% CI 0.99-0.99) and single ventricle CHD 0.99 (95% CI 0.97-0.99). By imaging modality, ICC for NCT was 0.98 (0.94-1.0), CCT 0.99 (0.99-0.99), and MRI 0.79 (0.32-1.0). By age, infants ICC was 0.99 (0.95-1.0), children 0.99 (0.98-0.99), and adults 0.97 (0.81-1.0). <h3>Conclusion</h3> The inter-rater reliability for total cardiac volume assessment in healthy and diseased hearts appears excellent across a variety of age groups and diagnoses. ICC for MRI was modest compared to CT imaging albeit the small sample size. Further validation of a standardized TCV measurement protocol among ACTION transplant centers is warranted.