Background and aims Early cardiac re-modelling in preterm animals and increased left ventricular mass (LVM) in young adults born preterm have been reported. We investigated LVM in infants for early adaptational myocardial changes during 6 months after preterm birth.

Method Longitudinal echocardiographic study measuring LVM in 25 preterm infants (GA 26–30) directly after birth, at term and 3 months post-term, and comparison to 30 age-matched term children after correction for body surface area (m²).

Results LVM/m² increased with 78% during the first three months after preterm birth (37.43 to 66.73 g/m²) compared to 13% in controls (49.39 to 55.70 g/m²). At term, LVM/m² was significantly higher in the preterm group (66.73 vs 49.39 g/m², p < 0.001). Preterm infants developed even more absolute LVM (12.79 vs 10.79 g, p = 0.02) although they were slightly lighter (3.18 vs 3.45 kg).

At three months of corrected age, relative LVM decreased, and no significant differences could be shown between the groups.

Conclusion Preterm infants develop an immediate but transient increase in LVM. Premature myocardial maturation, increased afterload and a narrower vascular tree might be responsible for left ventricular hypertrophy. The impact on short and long term left ventricular function is still unclear and has to be explored.