Serial Strain Analysis Identifies Hypoplastic Left Heart Syndrome Infants at Risk for Cardiac Morbidity and Mortality: A Pilot Study

Abstract

Validated, objective measures of right ventricular (RV) function assessment in hypoplastic left heart syndrome (HLHS) are needed. In other populations, speckle-tracking echocardiography-derived strain is a sensitive measure that outperforms conventional parameters of RV function. We hypothesized that speckle-tracking echocardiography-derived measures of RV function would be worse in patients with HLHS who have a poor cardiac outcome. Prospective serial echocardiography was performed in 35 infants with HLHS during the first 6months of life. Patients not undergoing staged palliation or with other variants of single RV were excluded. Traditional RV measurements and strain analysis were performed from standard apical and basal views. The primary outcome of cardiac death, heart transplantation, or persistent ≥moderate RV dysfunction was examined using Cox regression analysis, and receiver operating characteristic curve analyses were performed to derive cutoff values. At median follow-up of 10.9months (interquartile range 5.6, 15.2), eight patients reached the outcome and demonstrated worse RV strain measures compared with those without the outcome. A post-Norwood global longitudinal strain (GLS) of>-16% (area under the curve [AUC]=0.76; P=.04) and pre-Glenn GLS>-13% (AUC, 0.98; P≤.01) were highly sensitive and specific for poor outcome. Other thresholds included post-Norwood GLS rate (GLSr)>-1.15 %/s (AUC, 0.78; P=.03), pre-Glenn GLSr=-0.85%/sec (AUC, 0.89; P<.01), post-Glenn circumferential strain rate>-0.85%/sec (AUC, 0.92; P<.01), and GLSr>-0.85%/sec (AUC, 0.84; P=.02). Strain analysis may help identify at-risk HLHS infants. In this pilot study, interstage strain indices were worse in infants with HLHS who had a poor cardiac outcome.