Enlarged left atrial volume in hypertrophic cardiomyopathy: a marker for disease severity.
BACKGROUND
Patients with hypertrophic cardiomyopathy and left atrial (LA) enlargement have increased morbidity and mortality. We analyzed the clinical and echocardiographic factors related to LA enlargement, particularly the degree of left ventricular (LV) hypertrophy and diastolic function.


METHODS
A total of 104 patients with hypertrophic cardiomyopathy (age 53 +/- 15 years, 64% men) were divided into two groups based on the indexed LA volume (LAVI) (mL/m2) measured by echocardiography: group A (or smaller LAVI group, n = 43) was defined as LAVI < or = 34 mL/m2; and group B (or larger LAVI group, n = 61) as LAVI > 34 mL/m2. Detailed clinical and echocardiographic data were obtained. LV wall thickness was measured at 15 sites at 3 levels (base, mid, and apex). Diastolic function was assessed from mitral and pulmonary venous inflow velocities and Doppler tissue imaging.


RESULTS
Both groups were similar in terms of sex, functional class (1.6 +/- 0.8 vs 1.5 +/- 0.8, group B vs A, P = .64), and incidence of atrial fibrillation (13% vs 5%, P = .19). However, patients of group B had a significantly higher incidence of serious cardiovascular events (16.4% vs 2.3%, group B vs A, P = .024). Both groups had a similar degree of resting LV outflow tract obstruction (19 +/- 30 vs 12 +/- 13 mm Hg, group B vs A, P = .06). However, those in group B had a higher incidence of at least moderate mitral regurgitation (25% vs 5%, group B vs A, P = .007), more LV hypertrophy at 6 LV nonapical wall segments (P < .05-P < .001), and a higher hypertrophy (Wigle) score (6.2 +/- 2.2 vs 4.5 +/- 2.1, group B vs A, P < .001). In addition, patients of group B had a higher incidence of abnormal diastolic filling (57% vs 28%, group B vs A, P = .003), a higher early diastolic velocity/early diastolic mitral annular velocity (10.2 +/- 4.9 vs 7.5 +/- 2.9, group B vs A, P = .003), and a higher calculated LA pressure (14.8 +/- 6.5 vs 11.1 +/- 3.4 mm Hg, group B vs A, P = .0011).


CONCLUSIONS
Patients with hypertrophic cardiomyopathy and LA enlargement had more serious cardiovascular events and demonstrated greater LV hypertrophy, more diastolic dysfunction, and higher filling pressures.
Yang
Hua
H
Division of Cardiology, Department of Medicine, Toronto General Hospital, University Health Network, University of Toronto, Canada.
Woo
Anna
A
Monakier
Daniel
D
Jamorski
Michal
M
Fedwick
Katie
K
Wigle
E Douglas
ED
Rakowski
Harry
H
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002312:Cardiomyopathy, Hypertrophic / Q000145:classification / Q000150:complications / Q000000981:diagnostic imaging*; D015150:Echocardiography, Doppler / Q000379:methods*; D005260:Female; D006325:Heart Atria / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D018487:Ventricular Dysfunction, Left / Q000145:classification / Q000000981:diagnostic imaging* / Q000209:etiology