Significance of left atrial volume in patients < 20 years of age with hypertrophic cardiomyopathy.

Left atrial (LA) enlargement is an indicator of chronic elevation in left ventricular (LV) end-diastolic pressure as well as diastolic dysfunction. There is a lack of data on the significance of LA volume in the pediatric population. The objective of this study was to elucidate the relation between LA volume and diastolic dysfunction, clinical symptoms, and exercise capacity in young patients with hypertrophic cardiomyopathy. All patients aged <20 years with obstructive hypertrophic cardiomyopathy who underwent evaluation at the Mayo Clinic from 2002 to 2006 were retrospectively identified. Reviews of the LA volume index and other traditional diastolic Doppler echocardiographic parameters, as well as clinical data, were performed. A total of 88 patients (66 male) were studied. The median age at evaluation was 14 years. The mean LA volume index was 39 +/- 19 ml/m(2). Additional echocardiographic parameters included a mean LV outflow gradient of 55 +/- 51 mm Hg, a mean E/E' ratio of 14.0 +/- 7.6, and a mean maximal septal wall thickness of 23 +/- 9 mm. On univariate linear regression analysis, LA volume index had an excellent correlation with diastolic dysfunction grade (p <0.001, r(2) = 0.6), LV outflow tract gradient, mitral E/E', and the degree of mitral regurgitation. LA volume index was also positively associated with symptom score (p = 0.005) and maximal oxygen consumption on exercise test (n = 22; p = 0.01). On multivariate analysis, LA volume index was related to diastolic dysfunction grade (p <0.001) and mean mitral regurgitation grade (p = 0.05). In conclusion, this study demonstrates the potential clinical importance of LA volume index in pediatric hypertrophic cardiomyopathy as a marker of the severity of underlying diastolic dysfunction, symptom score, and decreased exercise capacity. LA volume index has significant diagnostic and prognostic value in these patients.