Left atrial strain and function in pediatric hypertrophic cardiomyopathy.
Jhaveri S, Komarlu R, Worley S, Shahbah D, Gurumoorthi M, Zahka K.J Am Soc Echocardiogr. 2021 Apr 26:S0894-7317(21)00431-4. doi: 10.1016/j.echo.2021.04.014. PMID: 33915246
Take home points:
- Left atrial (LA) strain and dysfunction are markers of diastolic dysfunction, associated with poor exercise capacity in hypertrophic cardiomyopathy patients. Children with phenotype positive hypertrophic cardiomyopathy have reduced LA function, measurable by both volumetric and strain analysis.
- LA conduit function, LA reservoir function and LA reservoir strain were lower in Phenotype positive hypertrophic cardiomyopathy than in Genotype positive and phenotype negative patients. Children with phenotypic HCM have lower left atrial strain values.
- Altered LA mechanics are associated with poor exercise capacity. Lower LA conduit function is associated with worsened aerobic capacity in pediatric HCM.
Commentary from Dr. Manoj Gupta (New York, USA), chief section editor of Pediatric & Fetal Cardiology Journal Watch
Literature on the assessment of diastolic dysfunction in pediatric HCM has focused primarily on the use of tissue Doppler indices, left atrial (LA) size, and inflow patterns. Research in adult HCM has shown that LAS values are independently associated with adverse outcomes, including heart failure, worsened exercise capacity, arrhythmias, stroke, and death.
Left atrial Parameters
Volumetric analysis of the left atrium was performed from apical four-chamber and two chamber views and was indexed to body surface area.
LA volume (LAV) was collected at three points in the cardiac cycle as follows:
(1) maximum LAV just before mitral valve opens (LAV max),
(2) minimal LAV at the end of diastole when the mitral valve closes (LAV min), and
(3) LAV just before atrial systole, before the p wave on electrocardiography (LAV pre-A).
Reservoir function = LAV max – LAV min/ LAV min
Conduit function = LAV max – LAV pre-A/LAV max
Booster pump function = LAV pre-A – LAV min/LAV pre-A
The HCM cohort consisted of 78 subjects with a median age of 16 years (range, 3–25 years), of whom 60 (64%) were male). Phenotypic criteria for HCM were present in 59% patients (P+ group, n = 46) whereas the remaining carried the genotype but lacked phenotypic characteristics (G+P- group, n = 32). (Table 1)
The maximal LA volume index (LAVI) was higher in patients with P+ HCM compared with the G+P- and control groups (median, 28 vs 20 vs 19 mL/m2 , respectively; P < .001).
Nearly one third of the P+ group (32% [n = 14]) had LAVI > 34 mL/m2 , which is the adult cutoff for LA dilation. Higher LAVI was associated with higher NTproBNP (r = 0.43; 95% CI, 0.05–0.71; P = .029).
Left atrial strain and volumetric function parameters were significantly lower in patients with phenotypic (P+) HCM compared with those with a positive genotype but without significant hypertrophy (G+P-).
On the basis of these results and known literature, it can be concluded that children with HCM have impaired reservoir and conduit function, similar to their adult counterparts. However, given that they have preserved contractile pump function in childhood years, it can be speculated that changes in their atrial contractile function probably take place as they age.
Altered atrial mechanics, as measured by volumetric and strain analysis, are present even in the pediatric population with phenotypic HCM.