To determine if interleukin-6 (IL6) and right ventricular (RV) function are independently associated in pulmonary arterial hypertension (PAH)
Elevated serum levels of IL6 identify PAH patients at increased risk of mortality, but the mechanism underlying this observation remains incompletely defined. Interestingly, pre-clinical and clinical data have revealed an association between IL6 and cardiac dysfunction, but the effect of IL6 on RV function, the major determinant of long-term outcomes in PAH, has not been examined.
We performed a single-center study of 40 patients with PAH from an institutional registry and analyzed how RV function was related to IL6.
IL6 had a negative logarithmic relationship with RV function as determined by echocardiography. There were no significant relationships between IL6 and mean pulmonary artery pressure (mPAP) and pulmonary vascular resistance (PVR), and only a weak association with pulmonary arterial compliance (PAC). When the cohort was divided by median IL6 level, patients with higher IL6 had significantly worse RV function on echocardiography, higher right atrial pressures, and reduced cardiac index and stroke volume despite having similar mPAP, PVR, and PAC. Finally, on multivariate analysis, IL6 was associated with RV function even after adjusting for PVR and PAC.
IL6 is independently associated with RV function in PAH, and patients with higher IL6 levels had more severe RV dysfunction. These findings suggest IL6 may contribute to RV dysfunction and thus could explain the poor survival in PAH patients with elevated IL6.