Cardiomyopathy-Associated Chronic Heart Failure in Infants Aged <1 Year: A Prospective Observational Cohort Over 5 Years in Northern China

Abstract

Background: There have been few large-scale studies on the outcomes of cardiomyopathy-associated heart failure (HF) in infants aged <1 year. This study aimed to assess longitudinal echocardiographic outcomes of infants with HF secondary to cardiomyopathy who survived for >1 year.

Methods and results: A prospective observational study following 327 infant patients up to 5 years in 2 large pediatric heart centers in Northern China between January 2010 and December 2018. A total of 236 (72.2%) patients had reduced left ventricular ejection fraction (LVEF) (HF with reduced ejection fraction group; LVEF <40%), 91 (27.8%) patients had midrange LVEF (HF with midrange ejection fraction group; LVEF ≥40% but <55%). LVEF improved significantly within the first year and remained stable in years 2 through 5 for both groups. The HF with midrange ejection fraction group had a higher rate of LVEF normalization (hazard ratio, 1.65; P<0.001). Baseline LVEF ≥40%, baseline left ventricular end-diastolic diameter Z score <7.8, the absence of left bundle-branch block, and the absence of β-blocker use were 4 independent favorable predictors for future LVEF normalization. A total of 62.4% of enrolled patients were diagnosed with left ventricular noncompaction. No significant difference in LVEF normalization was found among the different types of cardiomyopathy studied.

Conclusions: A significant number of infants with cardiomyopathy who survived >1 year were found to improve with medical therapies during the first year of diagnosis. Poorer outcomes were associated with decreased LVEF and increased heart size at diagnosis baseline, the presence of left bundle-branch block and use of β blockers. The Northern Chinese pediatric population may have a high proportion of left ventricular noncompaction.

Keywords: cardiomyopathy; echocardiography; heart failure; longitudinal; pediatrics.

Figure 1. Flowchart of study design.

DCM indicates dilated cardiomyopathy; EFE, endocardial fibroelastosis; HCM, hypertrophic cardiomyopathy; HF, heart failure; HFmrEF, heart failure with midrange ejection fraction; HFrEF, heart failure with reduced ejection fraction; IEM, inborn error of metabolism; LVEF, left ventricular ejection fraction; LVNC, left ventricular noncompaction; MCM, mitochondrial cardiomyopathy; RCM, restrictive cardiomyopathy; and TCM, tachycardia‐induced cardiomyopathy.

Figure 2. Changes in LVEF and LVEDD Z score with follow‐up time.

LVEFs of both the HFrEF group (blue pot and line) and the HFmrEF group (red pot and line) increased significantly within 1 y (A) and remained stable within 2 to 5 y (B). The dotted line indicates an LVEF of 55%. LVEDD Z scores of both the HFrEF group (blue pot and line) and the HFmrEF group (red pot and line) decreased significantly within 1 y (C) and remained stable within 2 to 5 y (D). The dotted line indicates a Z score of 2 or −2. P values indicate the significance of difference between the HFrEF and the HFmrEF groups. Median LVEF was plotted against follow‐up time using regression analysis with the 95% CIs within 1 y (E) and 2 to 5 y (F). HFmrEF indicates heart failure with midrange ejection fraction; HFrEF, heart failure with reduced ejection fraction; LVEDD, left ventricular end‐diastolic dimension; and LVEF, left ventricular ejection fraction.

Figure 3. Results of Kaplan–Meier curves indicating the time to LVEF normalization.

Analyses identified negative predictors of eventual LVEF normalization, including baseline LVEF <40% (A), baseline LVEDD Z‐score >7.8 (B), LBBB (C), and beta‐blockers (D). HFmrEF indicates heart failure with mid‐range ejection fraction; HFrEF, heart failure with reduced ejection fraction; LBBB, left bundle branch block; LVEDD, left ventricular end‐diastolic dimension; and LVEF, left ventricular ejection fraction.

Figure 4. LVEF normalization in patients stratified by cardiomyopathy subtypes.

Kaplan–Meier curves by showing cumulative probability of LVEF normalization among patients stratified by presence or absence of LVNC (A), DCM (B), and EFE (C) revealed no significant difference in LVEF normalization (P>0.05) among the different types of cardiomyopathy. DCM indicates dilated cardiomyopathy; EFE endocardial fibroelastosis; LVEF, left ventricular ejection fraction; and LVNC, left ventricular noncompaction.