Difference in pre‐ and postnatal prevalence of congenital cardiac tumors in a large population‐based cohort

Introduction Cardiac tumors in children are rare. Rhabdomyomas are the most common type in newborns, often associated with tuberous sclerosis. The exact prevalence of neonatal cardiac tumors is unknown. This study aimed to determine the pre‐ and postnatal prevalence of cardiac tumors in a population‐based cohort. Material and Methods This cross‐sectional study collected data from two sources: (1) all fetuses who underwent routine prenatal malformation scans (Weeks 18–21) with expected delivery within the study period (April 2016 and October 2018), and (2) all newborns who underwent systematic transthoracic echocardiography in the population‐based Copenhagen Baby Heart Study within the study period. Medical charts provided follow‐up data. Clinical trial registration: clinicaltrials.gov ; identifier: NCT02753348. Results Among 47 228 live‐births (51% male) in the study period, 1) 44 963 fetuses were scanned, with one prenatally diagnosed with a cardiac tumor (0.002% prevalence). Fetal autopsy revealed a cardiac rhabdomyoma. 2) Of 25 590 newborns (age 12 ± 8 days, 52% male) scanned, 7 had cardiac tumors (0.027% prevalence), a 14‐fold higher prevalence than prenatally ( p = 0.005). Tumors were located in the ventricles, predominantly (86%) multifocal, in otherwise normal hearts. Three affected newborns (43%) had tuberous sclerosis; the remaining four (57%) exhibited spontaneous tumor regression. Retrospective analysis of prenatal scans suspected a ventricular tumor in 1 of the 7 cases. Conclusions In a large, contemporary cohort, the pre‐ and postnatal prevalence of congenital cardiac tumors was 0.002% and 0.027%. This likely reflects the growth pattern of myocardial tumors and underscores the importance of gestational age for detection. Tumors in newborns were associated with tuberous sclerosis in 43%, and the remaining regressed spontaneously.