[Systemic sclerosis associated pulmonary arterial hypertension: the pitfalls].

Although pulmonary arterial hypertension (PAH) is usually considered as a late complication in limited subsets of systemic sclerosis (SSc), PAH can also occur in diffuse SSc and in early SSc. The evaluation of the velocity of the tricuspid regurgitation on echocardiography is so far the most effective screening tool for pulmonary hypertension (PH) in SSc. Nevertheless, it is not measurable in about 20% of SSc patients ; In that case, pulmonary arterial pressure can be evaluated by using the velocity of a pulmonary insufficiency and indirect signs of PH should be analyzed: pulmonary ejection time, right heart cavities dilatation and aspect of the inferior vena cava. About 10% of SSc patients with a suspected of PAH on echocardiography have post-capillary PH at right heart catheterization mainly due to left ventricular diastolic dysfunction. In some SSc patients, PAH and post-capillary PH due to left ventricular diastolic dysfunction may be associated. This can be suspected in case of post-capillary PH with a transpulmonary gradient > 12 mmHg. Lung fibrosis is another cause of PH in SSc. The distinction between PH associated to lung fibrosis from PAH is sometimes difficult, particularly in patients with a FVC between 60 and 70% of expected. Pulmonary veno-occlusive disease is a possible cause of precapillary PH in SSc. The diagnosis of pulmonary veno-occlusive disease should be discussed in each case of PAH associated ScS due to the high risk of lung edema at the introduction of specific PAH drugs.