Abstract 17362: Left Atrial Stiffness is Increased in Pediatric Hypertrophic Cardiomyopathy and May Be of Incremental Value in Predicting Major Adverse Cardiac Events in This Group

Abstract

Background: Determining risk factors by echocardiography to prevent major adverse cardiac events (MACE) is crucial in pediatric patients with hypertrophic cardiomyopathy (HCM). Recent studies have shown that LA stiffness and strain may serve as surrogate markers in children, to differentiate elevated pulmonary capillary wedge pressure from normal and predict COVID-19 related myocardial injury. Hypothesis: LA stiffness may predict MACE in pediatric patients with HCM. Methods: We retrospectively enrolled 201 pediatric patients with HCM diagnosed by echocardiography. They were divided into two groups: MACE (n=61) and non-MACE (n=140) groups. LV systolic function, and LA strain were evaluated by conventional 2D and speckle tracking echocardiography. Noninvasive LA stiffness was calculated as the ratio of E/e’ to LA strain as depicted in the following equation: LA Stiffness= E/e ' ratio / LA Peak Strain (% -1 ). The primary outcome was a composite endpoint of MACE (including ICD placement, myomectomy, heart transplant or death) during follow-up. Results: The MACE group showed significantly decreased LV global longitudinal strain (GLS) compared to non-MACE group (GLS - 16.76 ± 5.05% vs. - 20.25 ± 3.40%, p < 0.001), even though LV ejection fraction showed no significant difference between the two groups. LA peak strain was significantly reduced (21.96 ± 7.24% vs. 30.80 ± 7.10%, p < 0.001), whereas, noninvasive LA stiffness was significantly increased (0.72 ± 0.48 % -1 vs. 0.34 ± 0.16 % -1 , p < 0.001) in the MACE group. Among the LV diastolic indices, LA stiffness was the superior-most index for predicting MACE (see Table 1, Figure 1) (AUC: 0.814, cut off value: 0.49% -1 ). Also, LA stiffness was independently associated with increased risk of the composite endpoint of MACE (HR: 3.26 [95% CI: 1.77 -5.99]; P < 0.001, see Table 2). Conclusion: LA stiffness is a newly described index in children, that may be of incremental value in predicting risk of MACE in pediatric HCM patients.