Current Practice and Utility of Chromosome Microarray Analysis in Infants Undergoing Cardiac Surgery

Objective. Traditionally, karyotype and fluorescence in situ hybridization (FISH) were used for cytogenetic testing of infants with congenital heart disease (CHD) who underwent cardiac surgery at our institution. Recently, chromosome microarray analysis (CMA) has been performed in lieu of the traditional tests. A standardized approach to cytogenetic testing does not exist in this population. The purpose of this study was to assess the utility of CMA based on our current ordering practice. Design. We reviewed the records of all infants (<1 year old) who underwent cardiac surgery at our institution from January 2010 to June 2013. Data included results of all cytogenetic testing performed. Diagnostic yield was calculated as the percentage of significant abnormal results obtained by each test modality. Patients were grouped by classification of CHD. Results. Two hundred seventy-five (51%) of 535 infants who underwent cardiac surgery had cytogenetic testing. Of those tested, 154 (56%) had multiple tests performed and at least 18% were redundant or overlapping. The utilization of CMA has increased each year since its implementation. The diagnostic yield for karyotype, FISH and CMA was 10%, 12%, and 14%, respectively. CMA yield was significantly higher in patients with septal defects (33%, P =.01) compared with all other CHD classes. CMA detected abnormalities of unknown clinical significance in 13% of infants tested. Conclusions. In our center, redundant cytogenetic testing is frequently performed in infants undergoing cardiac surgery. The utilization of CMA has increased over time and abnormalities of unknown clinical significance are detected in an important subset of patients. A screening algorithm that risk-stratifies based on classification of CHD and clinical suspicion may provide a practical, data-driven approach to genetic testing in this population and limit unnecessary resource utilization.