Myocardial performance assessment in neonates by one-segment strain and strain rate analysis by tissue Doppler - a quality improvement cohort study

OBJECTIVES: To investigate one-segment strain and strain rate indices as measures of myocardial performance in asphyxiated term neonates. DESIGN: Quality improvement cohort study. SETTING: Newborns admitted to a neonatal intensive care unit at a Norwegian University Hospital for perinatal asphyxia and non-asphyxiated newborn recruited from the maternity ward at the same hospital. PARTICIPANTS: Twenty asphyxiated and 48 non-asphyxiated term neonates. PRIMARY OUTCOME MEASURE: Strain and strain rate indices and repeatability measures. One-segment longitudinal strain and strain rate by tissue Doppler were assessed on days 1, 2 and 3 of life in nine heart walls. Repeatability was compared against measurements from two-segment analyses previously performed in the same images. RESULTS: The 95% limits of agreement were significantly better for the one-segment than two-segment repeatability analyses, the inter-rater peak systolic strain (PSS) was (−3.1, 3.3) vs (−11.4, 18.3)%, the inter-rater peak systolic strain rate (PSSR) was (−0.38, 0.40) vs (−0.79, 1.15)/s, the intra-rater PSS was (−2.5, 2.6) vs (−8.0, 9.8)% and the intra-rater PSSR was (−0.23, 0.25) vs (−0.75, 0.80)/s (p<0.05). The myocardial performance was lower in the asphyxiated neonates (indices closer to zero) than in the non-asphyxiated neonates, PSS was −17.8 (0.6) (mean (SEM)) vs −21.2 (0.3)%, PSSR −1.43 (0.08) vs −1.61 (0.03)/s, early diastolic strain rate 1.72 (0.11) vs 2.00 (0.11)/s and strain rate during the atrial systole 1.92 (0.17) vs 2.27 (0.10)/s (p<0.05), despite no difference in fractional shortening (29.0 (0.5) vs 29.1 (1.0)%) (p>0.05). CONCLUSIONS: One-segment strain and strain rate assessed the reduced myocardial performance in asphyxiated neonates with significantly improved reproducibility as compared with two-segment analysis and was therefore more feasible than two-segment analyses for assessment of myocardial performance after perinatal asphyxia.