Left ventricular chamber stiffness at rest as a determinant of exercise capacity in heart failure subjects with decreased ejection fraction

1 Cardiovascular Biophysics Laboratory and 2 Section of Applied Physiology, Washington University School of Medicine, St. Louis, Missouri 63110 Submitted 22 January 2004 ; accepted in final form 14 June 2004 Impaired exercise tolerance, determined by peak oxygen consumption ( O 2 peak ), is predictive of mortality and the necessity for cardiac transplantation in patients with chronic heart failure (HF). However, the role of left ventricular (LV) diastolic function at rest, reflected by chamber stiffness assessed echocardiographically, as a determinant of exercise tolerance is unknown. Increased LV chamber stiffness and limitation of O 2 peak are known correlates of HF. Yet, the relationship between chamber stiffness and O 2 peak in subjects with HF has not been fully determined. Forty-one patients with HF New York Heart Association [(NYHA) class 2.4 ± 0.8, mean ± SD] had echocardiographic studies and O 2 peak measurements. Transmitral Doppler E waves were analyzed using a previously validated method to determine k , the LV chamber stiffness parameter. Multiple linear regression analysis of O 2 peak variance indicated that LV chamber stiffness k ( r 2 = 0.55) and NYHA classification ( r 2 = 0.43) were its best independent predictors and when taken together account for 59% of the variability in O 2 peak . We conclude that diastolic function at rest, as manifested by chamber stiffness, is a major determinant of maximal exercise capacity in HF. diastole; echocardiography; oxygen consumption Address for reprint requests and other correspondence: S. J. Kovács, Cardiovascular Biophysics Laboratory, Washington University School of Medicine, 660 South Euclid Ave., Box 8086, St. Louis, MO 63110 (E-mail: sjk{at}wuphys.wustl.edu ).