Utility of Fetal Cardiovascular Magnetic Resonance for Prenatal Diagnosis of Complex Congenital Heart Defects. Salehi D, Fricke K, Bhat M, Arheden H, Liuba P, Hedström E.
JAMA Netw Open. 2021 Mar 1;4(3):e213538. doi: 10.1001/jamanetworkopen.2021.3538.
- Fetal Cardiovascular Magnetic Resonance complements echocardiography in selected cases to confirm anatomy.
- Fetal CMR can add crucial diagnostic information that may be associated with better prenatal counseling, clinical decision-making, and adequate early postnatal care.
- Developments in fetal CMR in acquiring high-resolution images without postprocessing due to MR compatible doppler ultrasound device may increase clinical applicability.
Commentary from Dr. Venu Amula (Salt Lake City, UT, USA), section editor of Pediatric & Fetal Cardiology Journal Watch: Prenatal diagnosis improves morbidity and mortality in critical congenital heart disease by improving delivery care planning and preoperative management. Prenatal Ultrasound screening supported by fetal echocardiography remains the mainstay of diagnosing congenital heart defects. The frequency and accuracy of prenatal diagnosis are dependent on timely referral by obstetric care providers, accessibility to specialty congenital heart centers, and providers with such experience. Fetal diagnosis may be difficult in exceptional cases.
In this research article, Salehi et al. study a cohort of 31 fetuses over two and a half years at a tertiary care center who were referred for fetal CMR after an inconclusive echocardiogram. The authors make a case for the utility of fetal CMR for prenatal diagnosis of complex congenital heart defects where questions about the anatomy remain due to poor visualization after fetal echocardiography. The pediatric cardiologists make the referral for advanced imaging. While fetal CMR was the exposure, the outcome measured was any change in patient management because of the diagnostic information gained from the study.
The study results show that in 26 out of 31 cases (84%), the new information obtained from CMR had clinical utility and affected patient management or parental counseling. For 20 cases referred to confirm aortic arch anatomy, the authors report the addition of diagnostic information in 16, including confirmation of normal anatomy in four. Fifteen cases were referred with borderline left ventricle to assess atrioventricular valve anatomy and aid assessment of univentricular and biventricular outcome. Fetal CMR was able to assess AV valve anatomy, and the assessment was deemed correct in 92% of cases compared to the postnatal outcome. Improved imaging helped with early postnatal management in four cases of HLHS, changing the management from planned Cesarean section to vaginal delivery due to better visualization of unrestrictive interatrial communication and lack of pulmonary lymphangiectasia.
Given that the study is performed at a single center with advanced fetal CMR imaging, the experience may not be generalizable. Fetal echocardiography is comparatively easier to perform, and the technology is more widely available than the CMR; and the authors acknowledge that the utility of this advanced imaging is complementary. The cases were pre-selected based on a referral from a pediatric cardiologist introducing “indicator bias.” The cases were in the third semester due to the need for a relatively sizeable fetus for good imaging. The outcome measure is subjective. However, the study indicates that fetal cardiovascular magnetic resonance imaging, when available, may aid in further clarification of inconclusive cases and positively impact outcomes in this complex population. Cost, availability of human and technical expertise remain essential considerations.