Background Mitral valve abnormalities (MVA) include mitral valve regurgitation (MR), mitral valve prolapse (MVP), Barlow's mitral valve disease, and parachute MV. The prevalence of MVA has yet to be determined in an unselected population of newborns. Objective To determine the prevalence of MVA in unselected newborns and to assess the left ventricular (LV) structure and function in the neonatal heart with MR. Methods Transthoracic echocardiography (TTE) was performed within 28 days after birth in unselected neonates consecutively included in a prospective, multicenter, population-based study (2016–2018 (n=25,751)). TTE's were systematically reviewed for MR, MVP, Barlow's MV disease, and parachute MV. In a subgroup of 400 newborns with MR, the regurgitation was further classified as either traceable MR, mild MR, or moderate/severe MR based on the ratio of the trans-mitral jet in systole over the diastolic filling duration using M-mode in the 4-chamber view of the LV. Results Of 25,751 included newborns, we found a prevalence of MVA of 26.7%. (6,883/ 25,751). The prevalence of MR was 26.2%, MVP was 0.35%, Barlow's disease was 0.13%, and parachute mitral valve was 0.027%. MR was more frequent in females compared to males (50.4 vs 48.2%, p<0.01). Newborns with MR had enlarged left atrial diameter (11.91±2.03 mm vs 11.53±2.02 mm, p<0.01) and LV end-diastolic and end-systolic diameter (LVIDd 19.98±1.88 mm vs 19.87±1.83 mm, p<0.01, LVIDs 13.48±1.47 mm vs 13.31±1.41 mm, p<0.01), thicker LV posterior wall (2.19±0.60 mm vs 2.05±0.52 mm, p<0.01), increased early and atrial mitral inflow velocities (MV E velocity (0.65±0.14 m/sec vs 0.61±0.13 m/sec, p<0.01), MV A velocity (0.60±0.13 m/sec vs 0.57±0.13 m/sec, p<0.01)), but lower fractional shortening (32.54±4.22% vs. 32.96±4.17%, p<0.01) as compared to newborns without MVA. In subgroup analysis MR severity was classified as traceable in 44% (175/400) of cases, mild MR in 52% (209/400) of cases and moderate/severe MR in 4% (16/400) of cases. Comparing traceable MR with moderate/severe MR (19.48±1.88 mm vs 20.96±2.64 mm, p=0.01) and comparing mild MR with moderate/severe MR (19.85±1.92 mm vs 20.96±2.64 mm, p=0.04) showed significant increases in LV end-diastolic diameter. Conclusion Over one fourth of all newborns had a MV abnormality of which mitral regurgitation accounted for the vast majority. The presence of MR was associated with asymmetric LV remodeling and discrete changes in LV function. Subgroup analysis revealed that increment in MR severity was primarily associated with an increase in LV end-diastolic diameter. Funding Acknowledgement Type of funding source: Public hospital(s). Main funding source(s): Herlev-Gentofte Hospital

Background Congenital aortic valve regurgitation (AVR) has been estimated to be present in 0.25 per 1,000 live births globally. The true prevalence in an unselected large-scale cohort remains unknown. Presence of congenital AVR could indicate a structural valve abnormality and may result in long-term strain on the heart. Aim To find the true prevalence of AVR in a large cohort of unselected newborns. Methods Between April 2016 and October 2018, 25,752 newborns were consecutively included in a population-based prospective multicenter cohort and examined with transthoracic echocardiography within the first 30 days of life. Examinations with AVR were categorized as trivial AVR by the presence of a trivial diastolic transvalvular flow, or as non-trivial AVR by the presence of a significantly larger and visually observable transvalvular flow. In newborns with non-trivial AVR, the vena contracta, the duration of the transvalvular flow, and the duration of the diastole were measured. The cases were matched 1:4 with newborns with no AVR based on sex, gestational age at birth, birth weight and age at time of examination. Results AVR was identified in 329 newborns (1.3%). Of these, 260 were classified as trivial AVR, 69 (0.27%) were non-trivial AVR. Non-trivial AVR had significantly larger aortic roots at all points of measurement compared to controls (mean±SD): aortic valve annulus (7.3 (0.73) vs. 7.0 (0.63) mm), Sinus of Valsalva (10.3 (1.0) vs. 9.7 (1.0) mm), sino-tubular junction (8.4 (0.8) vs. 8 (0.8) mm), and ascending aorta (10 (0.9) vs. 9.4 (1.1) mm) (p<0.01 for all). Left ventricular dimensions and function did not significantly differ between the cases and controls. The presence of a non-trivial AVR was highly associated with a bicuspid aortic valve (9 (13.0%) vs. 3 (1.1%), p<0.001). Conclusions We found a prevalence of congenital AVR of 1.3% in a large cohort of unselected newborns, which is higher than previously reported. One in five of all AVR found were classified as non-trivial. Newborns with non-trivial AVR presented with larger aortic root and ascending aorta dimensions. Newborns with non-trivial AVR also had a ten-fold higher occurrence of bicuspid aortic valve compared to controls. Funding Acknowledgement Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): Hjerteforeningen