From a Regional Cohort of Extremely Low Birth Weight Infants: Cardiac Function at the Age of 7 Years

Abstract

Background: The long-term impact of prematurity on cardiac structure and function has not yet been fully discovered. Objectives: To assess long-term cardiac complications in the regional cohort of extremely low birth weight (ELBW) children born in 2002-2004. Material and Methods: Eighty-one children born as ELBW infants (91% of the available cohort) with a median birth weight of 890 g (25-75th percentile: 760-950) were evaluated at the mean age of 6.7 years. The control group included 40 children born full-term, selected from one general practice in the district. Echocardiography and 24-hour ambulatory blood pressure measurements (ABPM) were performed. The primary outcome variable was the presence of cardiac complications such as left ventricular hypertrophy (LVH), diastolic dysfunction or systolic dysfunction. Results: LVH was diagnosed in 4/81 ELBW children and 2/40 control children (p = 1.0). Concentric remodeling was detected in 8 (10%) subjects from the ELBW group and in 2 (5%) from the control group (p = 0.49). There were no patients with diastolic or systolic dysfunction in either group. After having expressed the results of M-mode echocardiography as z-scores for body surface area (BSA), statistically significant differences were observed for right-ventricle dimension in diastole (-1.49 ± 1.25 vs. -0.31 ± 0.91; p < 0.001), LV inner dimension in diastole (-0.53 ± 1.26 vs. 0.13 ± 0.94; p = 0.01) and left atrium (-0.93 ± 1.07 vs. -0.15 ± 1.02; p < 0.01). Heart rate (HR) was significantly faster in ELBW children (92.9 ± 8.4 vs. 86.7 ± 7.4 bpm; p = 0.01 adjusted for BSA) and they also had significantly higher night-time blood pressure [mean (z-score): 1.15 vs. 0.2; p = 0.02] without nocturnal dipping (night-time dipping <10%: 13 (16.7%) vs. 2 (5.2%), p = 0.13). Conclusions: No differences were found between the groups in the occurrence of cardiac complications. Ex-preterm ELBW children at age 6 may have a faster HR, smaller cardiac dimensions on echocardiography and higher nocturnal blood pressure. The clinical relevance of these findings is unknown.