Left ventricular myocardial deformation and mechanical dyssynchrony in children with normal ventricular shortening fraction after anthracycline therapy

Abstract

Objective: The M-mode-derived left ventricular shortening fraction is incorporated into most of the paediatric oncology protocols for monitoring of cardiotoxicity. This study tested the hypothesis that alteration of left ventricular myocardial deformation and mechanical dyssynchrony may occur in asymptomatic children after anthracycline therapy despite having left ventricular shortening fractions within the limits of normal. Design: Cross-sectional study. Setting: Tertiary paediatric cardiac centre. Methods: Left ventricular longitudinal, circumferential and radial myocardial deformation was determined using speckle tracking echocardiography in 45 patients aged 15.3±5.8 years. Real-time three-dimensional echocardiographic data were acquired for the measurement of left ventricular volumes and systolic dyssynchrony index (SDI), the latter derived from the dispersion of time-to-minimum regional volume using a 16-segment model. The results were compared with those of 44 controls. Results: Compared with controls, patients had reduced left ventricular global systolic longitudinal strain (p=0.012), circumferential strain (p<0.001), radial strain (p=0.006) and circumferential strain rate (SR; p=0.002). The cumulative anthracycline dose correlated negatively with global longitudinal (r=-0.33, p=0.027) and circumferential (r=-0.32, p=0.035) SR. The left ventricular SDI was significantly greater in patients than controls (4.46±1.52% vs 3.80±0.58%, p=0.03). The prevalence of left ventricular mechanical dyssynchrony (SDI >4.96%) in patients was 16% (95% CI 6% to 29%). In patients, SDI correlated negatively with left ventricular ejection fraction (r=-0.52, p<0.001), radial strain (r=-0.35, p=0.021), circumferential strain (r=-0.37, p=0.015) and circumferential SR (r=-0.43, p=0.004), but not with the cumulative anthracycline dose (p=0.82). Conclusions: Impaired left ventricular myocardial deformation and mechanical dyssynchrony may exist in children after anthracycline therapy despite having normal left ventricular shortening fractions.