Factors relating to impaired stroke volume during the 6-minute walk test in patients with systemic sclerosis

Systemic sclerosis impairs the dilatation of affected pulmonary blood vessels and myocardial diastolic function at rest, but few studies have examined cardiac hemodynamic response during exercise. This study aimed to evaluate the factors affecting cardiac response during submaximal exercise in patients with systemic sclerosis.

Fifty-nine consecutive patients and 27 age- and sex-matched healthy controls underwent the 6-minute walk test with a non-invasive impedance cardiograph device.

Stroke volume and cardiac output in patients with systemic sclerosis were significantly lower than those in controls at rest and at the end of the 6-minute walk test, and the distance walked was significantly shorter in patients. Percent predicted of forced vital capacity and diffusion capacity of the lung in patients showed correlations with stroke volume at the end of the 6-minute walk test and the increase in stroke volume during walking. The echocardiographic findings of right ventricular systolic pressure and left ventricular diastolic dysfunction showed no relationship to stroke volume during the 6-minute walk test. The increase in stroke volume during the 6-minute walk test was significantly smaller in patients with pulmonary hypertension diagnosed by right-heart catheterization than in those without pulmonary hypertension.

Impaired stroke volume in patients with systemic sclerosis was observed at rest and during exercise, and the factors relating to the cardiac response seemed to be pulmonary function and the extent of pulmonary hypertension.