The Effects of Apelin on serum NT-proBNP levels in Pulmonary Hypertension Patients GS Reid, KS Wilson, K Suveizdyte, L Brash, AJ Peacock, DJ Welsh. Scottish Pulmonary Vascular Unit, Western Infirmary, Glasgow, G11 6NT. Results Introduction Pulmonary hypertension (PH) is defined as a mean pulmonary arterial pressure of >25mmHg. There are several causes of PH including pulmonary arterial hypertension and left heart failure. Currently therapy is limited to symptomatic relief and the prognosis is poor. Apelin has been identified as a new therapy for PH. It has been shown to have inotropic and vasodilatory properties in man. Apelin exerts some of its action by increasing nitric oxide levels in smooth muscle. Studies also indicate Apelin may be able to reverse the pathological vessel remodelling seen in PH. NT-proBNP is used as a marker of disease severity in PH. Treatments that reduce NT-proBNP are associated with reduced mortality. Figure 1 – Mean Pre infusion Levels of NT-pro BNP with 95% C.I. There was no significant difference between groups, P=0.287 for a one-way ANOVA Figure 31 - Change in cardiac output from baseline during Apelin and Placebo infusion in PAH patients. Apelin caused a significant increase in cardiac output. *P<0.01 **P<0.001 two-way ANOVA between Apelin and Placebo1 Aims This study aimed to investigate, for the first time, the effects of apelin on serum NT-proBNP concentration in groups of pulmonary hypertension patients and controls. The hypothesis of the study was that apelin would cause a change in NT-proBNP. Discussion Despite the lack of change in NT-proBNP levels seen in this study, the haemodynamic response pattern reported for apelin1 has been associated with NT-proBNP changes in other drug studies. The lack of response in this study was likely due to the short time period over which effects were measured. Methods Serum samples from patients recruited for a haemodynamic investigation of apelin were used1. The groups studied were controls, pulmonary arterial hypertension and pulmonary hypertension due to left heart failure NT-proBNP concentrations in serum samples were determined using ABNOVA sandwich ELISA kits. Conclusion NT-proBNP levels do not immediately change in response to several minutes of apelin infusion. This is consistent amongst control and pulmonary hypertension patients. Investigation of therapy over a longer time period is required to truly evaluate if apelin has any effect on NT-proBNP levels. Figure 2 – Mean change in NT-proBNP levels post Apelin infusion with 95% C.I. There was no significant change for any group, P=0.830 for a paired sample T-test between pre and post Apelin infusion levels. In addition there was no significant difference between group means, P=0.363 for one-way ANOVA. References L Brash, C Church, JS Gibbs, LSGE Howard, MK Johnson, DJ Welsh, MR Wilkins, DE Newby, AJ Peacock. Apelin improves cardiac output in patients with pulmonary arterial hypertension. Submitted to ERS 2015 Conference