889: Utility of Noninvasive Prenatal Testing (NIPT) in evaluation of Congenital Heart Defects (CHD)

Abstract

NIPT side steps many of the issues associated with invasive fetal testing, and has become a popular screening tool in assessing chromosome abnormalities when fetal anomalies are identified. Our clinical experience suggested NIPT has low yield in fetuses with heart defects. This study describes the utility of NIPT in specific classes of congenital heart disease. Retrospective chart analysis identified pregnancies with isolated (I) or non-isolated (NI) fetal CHD. Inclusion criteria: confirmed cardiac diagnosis, prenatal NIPT results known, abnormal postnatal chromosome results. CHDs were classified based on their embryological development: 1) hypoplastic left heart (HLH); 2) transposition of great arteries (TGA); 3) truncus arteriosus (TA); 4) conotruncal defects (CT); 5) atrioventricular septal defect (AVSD); 6) muscular septal defects (mVSD); 7) right aortic arch (RAA); 8) coarctation of aorta (CoA)/interrupted aortic arch (IAA); and, 9) right sided defects. Utility of NIPT was defined as the chance NIPT could provide a causative diagnosis for the CHD ( T21, T18, T13, 45,X, triploidy, del22q11.2) to the patient to supplant invasive testing in confirmed (I) and (NI) CHD groups Eighty two babies with abnormal chromosomes were studied, 57 with isolated defects and 25 with both cardiac and extracardiac abnormality. Table 1 shows the percentage of cases predicted accurately by NIPT, ordered by CHD class. The highest utility of NIPT in (I) and (NI) cases was in cases with TA or AVSD, 100% and 94.4%, respectively. NIPT gave no valuable information in isolated HPLH, TGA, or RAA. Overall yield of NIPT was 64% for isolated CHD, 70.7% for non-isolated cases. Genetic conditions not identified by NIPT in NI CHD cases include microarray abnormalities and single gene conditions (Noonan syndrome). Two cases of aortic coarctation were diagnosed with mosaic Turner syndrome; the technology of NIPT may be limited in mosaic cases. NIPT has satisfactory (although not complete) utility in AVSD and CT abnormalities more often associated with standard aneuploidies. A low-risk result from NIPT does not eliminate microarray abnormality for all other types of CHD and is not reliable enough to substitute for invasive fetal testing. Invasive procedures have modest associated risks, but the additional information they provide may be key for families and healthcare providers. The CHD category is an important factor to consider if NIPT is offered as an option.