P4521C-reactive protein as a predictor for diastolic dysfunction in patients with sleep-disordered breathing

Abstract

Abstract Background Sleep-disordered breathing (SDB) is often associated with left ventricular diastolic dysfunction, but the mechanisms are poorly understood. SDB may increase systemic inflammation that could induce myocardial fibrosis leading to diastolic dysfunction. Purpose Systemic inflammation and diastolic dysfunction were analysed in patients with SDB. Methods 295 patients undergoing coronary artery bypass grafting were included in the prospective observational trial CONSIDER-AF (NCT02877745). They were screened for SDB in the preoperative night and an apnoea-hypopnea index (AHI) of ≥15/h defined SDB. Preoperative echocardiography was used to measure the ratio of early (E) and late (A) diastolic transmitral flows (E/A), early diastolic mitral annular velocity (E'), the ratio E/E', LA volume index, and tricuspid regurgitation velocity. Left ventricular diastolic dysfunction was graded I-IV according to current guidelines. Patients with ventricular ejection fraction of less than 45% were excluded. We used serum C-reactive protein (CRP) as a marker for systemic inflammation, resulting in a full data set for 170 patients. Results In patients with SDB, serum CRP levels were 3.036 mg/L higher than in control patients (95% confidence interval: −0.393–6.466, P=0.082). Intriguingly, the severity of SDB (AHI) correlated significantly with the CRP levels (coefficient B: 0.13±0.06, P=0.021). CRP also correlated with the severity of diastolic dysfunction (coefficient B: 0.010±0.004, P=0.009). Importantly, multivariable linear regression analysis accounting for the potential confounders age, sex, body-mass index, existing atrial fibrillation, diabetes, AHI, and creatinine indicated that CRP was an independent predictor for the severity of diastolic dysfunction (coefficient B: 0.009±0.004, P=0.016). Interestingly, the latter effect was still present considering just patients with SDB (coefficient B: 0.013±0.005, P=0.015, N=72), but was completely abolished in patients without SDB (coefficient B: 0.001±0.007, P=0.912, N=98), indicating a potential SDB-dependence. Conclusion Systemic inflammation (CRP) is associated with the severity of SDB (AHI). Interestingly, only in SDB patients CRP predicts significantly and independently the severity of diastolic dysfunction. Consequently, anti-inflammatory therapeutic strategies could be beneficial for patients with SDB and diastolic dysfunction. Acknowledgement/Funding This study was supported by Philips Respironics and the Medical Faculty of the University of Regensburg.