Clinical features and long-term survival in idiopathic pulmonary arterial hypertension with thyroid dysfunction: insights from a national multicentre prospective study

BACKGROUND: Our objective was to clarify the characteristics and long-term survival of idiopathic pulmonary arterial hypertension (IPAH) patients with thyroid dysfunction and compare them with IPAH without thyroid dysfunction. METHODS: A retrospective analysis was conducted using prospectively collected data. IPAH patients with thyroid dysfunction at baseline were included. Patients with other subgroups of PAH and Group 2–5 pulmonary hypertension were excluded. IPAH patients with euthyroid function were matched 1:1 to IPAH patients with thyroid dysfunction by age and sex. RESULTS: In total, 148 IPAH patients with thyroid dysfunction were included. Patients with hyperthyroidism, hypothyroidism, subclinical hyperthyroidism and subclinical hypothyroidism accounted for 16.2%, 18.9%, 8.1% and 56.8%, respectively. IPAH patients with hyperthyroidism showed the highest mixed venous oxygen saturation (S(vO(2))) and the lowest pulmonary vascular resistance (PVR) at baseline among subgroups, while patients with subclinical hypothyroidism had the lowest S(vO(2)) and highest PVR (p<0.05). Compared with IPAH without thyroid dysfunction, patients with hyperthyroidism (9.14 versus 13.86 WU; p<0.05) and hypothyroidism (10.70 versus 13.86 WU; p<0.05) showed significantly lower PVR. The haemodynamic profiles of patients with subclinical hypothyroidism were similar to IPAH with euthyroid function except for lower right atrial pressure (6 versus 8 mmHg; p=0.009). The long-term survival of patients with clinical thyroid dysfunction was better than IPAH without thyroid dysfunction, while that of those with subclinical diseases was comparable to the latter, even after adjusting for baseline haemodynamics and treatment. CONCLUSION: IPAH patients with clinical hyper- and hypothyroidism had better haemodynamics and survival than those without thyroid dysfunction, while patients with subclinical hypothyroidism had similar haemodynamics and survival profiles to the latter.