Nitric oxide metabolites in heart failure patients with reduced or preserved ejection fraction and effects of different exercise modes

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): German Centre for Cardiovascular Research (DZHK). Background Alterations of endothelial function and nitric oxide (NO) release are involved in pathophysiology and clinical symptoms of heart failure (HF). Regular exercise training improves vascular and endothelial function and is closely linked to mechanisms of NO pathway by enhancing endothelial NO synthesis. However, it is not well investigated how exercise training affects metabolites of the NO pathway and whether different exercise modes have different effects on NO bioavailability in HF. Purpose The aims of this analysis were to 1) investigate differences in serum levels of the NO metabolites L-arginine, homoarginine, asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) between patients with HF with reduced (HFrEF) or preserved ejection fraction (HFpEF) and 2) to investigate effects of high-intensity interval training (HIIT) and moderate continuous training (MCT) on these parameters. Methods Patients with HF from two clinical exercise intervention trials were included in this analysis. In both trials, patients were randomized (1:1:1) either to HIIT, MCT or guideline control (CG). Clinical data and blood samples were collected at baseline, after three months of supervised exercise training and after 12 months follow-up. NO metabolites were analysed from EDTA-plasma using liquid chromatography-tandem mass spectrometry (LC–MS/MS). Results Data from 366 patients with HF, including 206 HFrEF (median [1. and 3. quartile]: 61 [53;70] years, 18.9% females) and 160 HFpEF patients (71 [66;76] years, 65.6% females), was available for analysis. Patients with HFrEF or HFpEF showed no significant differences in NYHA classification (NYHA III: 30.6% vs. 26.2%, p=0.43) or presence of diabetes mellitus (23.8% vs. 26.2%, p=0.50), while HFpEF had a higher prevalence of hypertension (86.9% vs. 38.5%, p<0.001) but a smaller number of current smoker than HFrEF (4.4% vs. 18.0%, p<0.001). PeakVO2 (18.4 [14.5;22.6] ml/min/kg vs. 17.0 [14.3;20.4] ml/min/kg, p=0.03) and HDL-cholesterol (56 [46;65] mg/dl vs. 42 [36;54] mg/dl, p<0.001) were higher in HFpEF than in HFrEF. At baseline, homoarginine and ADMA levels were higher in HFrEF than in HFpEF, but no differences in L-arginine or SDMA could be observed (Table 1). Changes in metabolite levels from baseline to 3 and 12 months were not significantly different between groups (HIIT, MCT, CG) in either HF phenotype (all p>0.05). In all exercise groups, median adherence to training sessions was at 85% or above with no significant differences between groups (p>0.05). Conclusion At baseline, patients with HFrEF had significantly higher homoarginine and ADMA levels compared to patients with HFpEF. However, in both HF phenotypes neither MCT nor HIIT induced significant changes in serum levels of NO metabolites when compared to patients randomized to CG.