Background : It has been difficult to noninvasively assess right ventricular (RV) function due to its complex geometric shape. Myocardial acceleration during isovolumic contraction (IVA) was demonstrated as a preload and afterload independent measurement of RV contractile function. In this study, we assessed subclinical RV dysfunction using IVA in patients with pulmonary hypertension due to chronic obstructive pulmonary disease (COPD) without visual RV hypokinesia. Methods and Results : We examined 20 patients with COPD in the state of moderate pulmonary hypertension and normal RV ejection fraction (EF) without visual RV hypokinesia and 20 normal controls. Pulmonary arterial systolic pressure (PASP) was evaluated using tricuspid regurgitant flow. RV ejection fraction and RV wall thickness were measured from 2-D echocardiography. RV tissue Doppler image was taken and analyzed by offline study. IVA was measured by dividing peak velocity of the isovolumic contraction by the time interval from onset of the isovolumic contraction wave (zero-crossing) to peak velocity of this wave at mid level of RV free wall. Mean PASP was 57.2+5.9 mmHg and 24.9+4.0 mmHg in COPD patients and controls. IVA was 186.24+153.14 cm/s2 and 259.14+147.93 cm/s2, respectively (p<0.05). The thickness of RV free wall during diastolic phase and RV EF were not significantly different between two groups. Conclusions : Although the patient did not show decreased RV EF in the state of moderate pulmonary hypertension, mean IVA of the patients with moderate pulmonary hypertension was decreased compared with that of normal controls. So we think that the contractile function of RV was decreased due to pressure overload and IVA may be the early index of subclinical RV dysfunction in COPD patients.