Sensitive cardiac troponin I predicts poor outcomes in pulmonary arterial hypertension

Circulating cardiac troponins are markers of myocardial injury. We sought to determine whether cardiac troponin I (cTnI), measured by a sensitive assay, is associated with disease severity and prognosis in pulmonary arterial hypertension (PAH). cTnI was measured in 68 patients with PAH diagnostic category 1 in a research-based sensitive immunoanalyser with a lower limit of detection of 0.008 ng.mL(-1). The associations between cTnI and PAH severity and clinical outcomes were assessed using Chi-squared and Wilcoxon rank sum tests, Kaplan-Meier analysis and Cox regression models. cTnI was detected in 25% of patients. Patients with detectable cTnI had more advanced functional class symptoms, a shorter 6-min walk distance, more pericardial effusions, larger right atrial area, and higher B-type natriuretic peptide and C-reactive protein levels. 36-month transplant-free survival was 44% in patients with detectable cTnI versus 85% in those with undetectable cTnI. cTnI was associated with a 4.7-fold increased risk of death related to right ventricular failure or transplant (hazard ratio 4.74, 95% CI 1.89-11.89; p<0.001), even when adjusted individually for known parameters of PAH severity. Elevated plasma cTnI, even at subclinically detectable levels, is associated with more severe disease and worse outcomes in patients with PAH.