Does left heart disease cause most systemic sclerosis associated pulmonary hypertension?

In this issue of the European Respiratory Journal, FOX et al. [1] present data that suggest most pulmonary hypertension (PH) in systemic sclerosis is post-capillary and that many patients are receiving pulmonary vasodilator therapy inappropriately. Of 53 patients identified as having PH, nearly half (24) had elevated wedge pressures, a further five had elevated left ventricular end-diastolic pressure and another six were ‘‘exposed’’ as having occult post-capillary abnormalities in response to a 500-mL fluid challenge administered over 5–10 min. Thus, in total, 35 (67%) out of 53 PH patients did not have pulmonary arterial hypertension (PAH). The number of patients with elevated pulmonary artery occlusion pressures (PAOP) is high when compared with other studies [2, 3] and there is no ‘‘threshold’’ wedge pressure that differentiates normality from cardiac disease during fluid challenge [4, 5], but this misses the bigger point. Their work illustrates the flaws in the accepted diagnostic benchmark.