Left atrial volumetric remodeling is predictive of functional capacity in nonobstructive hypertrophic cardiomyopathy.
BACKGROUND
The left atrium is afterload sensitive, responding to immediate changes in left ventricular (LV) diastolic pressure, and left atrial volumetric remodeling has been reported in conditions associated with abnormal diastolic function. We examined the relationship between left atrial volumetric remodeling and objective measures of exercise capacity in patients with nonobstructive hypertrophic cardiomyopathy (HCM).


METHODS
We compared LA volume indices, other 2-dimensional and Doppler echocardiographic parameters, invasive hemodynamic measures, and magnetic resonance imaging (MRI)-derived LV mass with exercise duration, maximal oxygen uptake (MV* O2), anaerobic threshold (AT), and ventilatory efficiency (VE/V* CO2 slope) in 43 patients with nonobstructive HCM. Patients underwent cardiac catheterization within 48 hours and metabolic stress testing within 1 week of their echocardiogram and MRI examinations.


RESULTS
Left atrial volume at end-ventricular systole (LA max) and end-atrial emptying (LA min) correlated with MV* O2 (r = -0.39, P < .01 for both), AT (r = -0.42, r = -0.39, respectively, P < .01 for both), and VE/V* CO2 slope (r = 0.45, P = .003; r = 0.41, P = .008). Patients with an LA max > or =33 mL/m2 had significantly lower MV* O2 (P = .025) and AT levels (P = .017) and higher VE/V* CO2 slope levels (P = .004) as compared with patients with a smaller LA size. In multivariate analysis, MRI-determined LV mass, which was not a univariate correlate of exercise tolerance, provided additional effect when combined with LA volume index.


CONCLUSIONS
Left atrial volumetric remodeling predicts exercise capacity in nonobstructive HCM and may reflect chronic LV diastolic burden. This simple noninvasive measure of LA size may provide a long-term indication of the effects of chronically elevated filling pressures in patients with HCM and further studies testing its prognostic value are necessary.
Sachdev
Vandana
V
Echocardiography Laboratory, Cardiovascular Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Md 20892, USA. sachdevv@nhlbi.nih.gov
Shizukuda
Yukitaka
Y
Brenneman
Cynthia L
CL
Birdsall
Charles W
CW
Waclawiw
Myron A
MA
Arai
Andrew E
AE
Mohiddin
Saidi A
SA
Tripodi
Dorothy
D
Fananapazir
Lameh
L
Plehn
Jonathan F
JF
D000328:Adult; D000332:Aerobiosis; D006328:Cardiac Catheterization; D003187:Compliance; D015150:Echocardiography, Doppler; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006325:Heart Atria / Q000503:physiopathology*; D006346:Heart Septum / Q000473:pathology; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000503:physiopathology*; D017380:Hypertrophy, Right Ventricular / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008944:Mitral Valve Insufficiency / Q000150:complications; D009929:Organ Size; D010101:Oxygen Consumption; D011312:Pressure; D012189:Retrospective Studies