Background Trimethylamine N-oxide (TMAO), the gut microbiota-dependent metabolite, is a potential biomarker in several cardiovascular diseases. However, no study has investigated its value in pulmonary hypertension (PH). Therefore, this study aimed to explore the association between plasma TMAO levels and prognosis in patients with PH. Methods Inpatients with idiopathic/heritable pulmonary arterial hypertension (IPAH/HPAH), PAH associated with congenital heart disease (CHD-PAH), and chronic thromboembolic pulmonary hypertension (CTEPH) at Fuwai Hospital were enrolled after excluding those with relative comorbidities. The endpoint was defined as a composite outcome including death, rehospitalisation due to heart failure, and at least 15% decreased 6-min walk distance from the baseline. Fasting blood samples were collected to measure plasma levels of TMAO and other clinical indicators. The associations between TMAO levels with disease severity and patients’ prognosis were investigated. Results In total, 163 patients with PH were included, with a mean follow-up duration of 1.3 years. After adjusting for confounding factors, elevated TMAO levels were still associated with severe disease conditions. TMAO levels dynamically decreased in stable and improved patients after treatment [ΔTMAO = − 0.2 (− 1.6, 0.7) μmol/L, P = 0.006]. Moreover, high plasma TMAO levels predicted a poor prognosis in the PH cohort (P < 0.001), and the association remained significant after adjusting the confounders, including treatment, risk stratification, and PH subtypes. Conclusion Elevated plasma TMAO levels were associated with severe disease conditions and poor prognosis in patients with PH, indicating its potential biomarker role in PH.

Background Arrhythmia is not uncommon among pulmonary hypertension (PH) population, and may be associated with disease severity. Hypothesis To investigate different spectrums and prevalence of arrhythmias in different clinical PH groups in Chinese population. Methods Patients diagnosed with PH between April 15, 2019, and August 2, 2021, were enrolled prospectively. The prevalence of different types of arrhythmias in PH patients were calculated. Logistic regression analyses were conducted to determine independent predictors for arrhythmia. Results One thousand patients were enrolled. The prevalence of any arrhythmia, sinus node dysfunction, sinus tachycardia, atrial fibrillation, atrial flutter, other types of atrial tachycardia, atrioventricular block, and ventricular tachycardia is 44.4%, 12.2%, 15.2%, 8.1%, 4.1%, 10.2%, 7.1%, and 2.5%. Logistic regression analyses revealed that older age and larger right ventricle (odds ratio: 1.111 and 1.095, p < .05) were independently related with higher probability of supraventricular arrhythmia; Complicating with coronary artery disease, larger right ventricle, and increased left ventricular end‐diastolic diameter (odds ratio: 19.540, 1.106, and 1.085, p < .05) were independently correlated with sinus node dysfunction/atrioventricular block in patients with pulmonary arterial hypertension. Conclusions Nearly half of PH patients experienced at least one type of arrhythmia. The most common seen arrhythmias were supraventricular arrhythmia, sinus tachycardia, and sinus node dysfunction. Older age and larger right ventricle were independently related with higher probability of supraventricular arrhythmia; Complicating with coronary artery disease, larger right ventricle and increased left ventricular end‐diastolic diameter were independently correlated with higher probability of sinus node dysfunction/atrioventricular block in patients with pulmonary arterial hypertension.