Diastolic heart dysfunction, increased pulmonary capillary wedge pressure and impaired exercise tolerance in patients with systemic sclerosis

Abstract

Background: Diastolic heart dysfunction, responsible for dyspnoea in heart failure patients, is an important prognostic factor. Patients with systemic sclerosis (SSc) serve as a model of diastolic heart failure with preserved ejection fraction.

Aim: To quantify diastolic left ventricular (LV) dysfunction and elevation of pulmonary capillary wedge pressures (PCWP) in SSc patients and to assess the effects of these parameters on exercise tolerance.

Methods: In 46 SSc patients (43 females, three males, aged 24-73 years) and 30 healthy females, echocardiography with tissue Doppler (TDE) and cardiopulmonary exercise tests (CPX) were performed. During TDE, the systolic (S) and early diastolic (E) velocities of mitral annulus were recorded. The PCWP was calculated on the basis of mitral inflow E velocity and E velocity of mitral annulus. The CPX was performed using a modified Bruce protocol.

Results: Left ventricular ejection fraction was normal in the SSc group. Mitral inflow E/A ratio was pseudonormal in five SSc patients, and significantly decreased in the remainder as compared to controls (0.87 ± 0.2 vs 1.38 ± 0.5, p < 0.0002). The TDE examination confirmed normal systolic LV function, but severe LV diastolic dysfunction (E 8.66 ± 2.5 cm/s vs 12.39 ± 3.5 cm/s in controls, p < 0.000002). The PCWP was higher in the SSc group (11.8 ± 3.3 mm Hg vs 7.7 ± 1.7 mm Hg in controls, p < 0.0001). The PCWP > 10 mm Hg significantly decreased exercise duration, maximal oxygen uptake and carbon dioxide output and identified patients with oxygen uptake < 20 mL/kg/min with 100% sensitivity and 78% specificity. The ventilatory equivalent of carbon dioxide was increased in the SSc group (VE/VCO2 38.7 ± 7.5 vs 30.55 ± 4.2 in controls, p < 0.002).

Conclusions: Pure LV diastolic dysfunction, typical of SSc, leads to the elevation of PCWP. Values of PCWP > 10 mm Hg are associated with severe exercise intolerance demonstrated by shorter duration of exercise with decreased oxygen uptake and carbon dioxide output during exercise.