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Serum bilirubin predicts long-term clinical outcomes in patients with cardiac syndrome X
  1. Shao-Sung Huang1,2,
  2. Po-Hsun Huang1,2,3,
  3. Hsin-Bang Leu1,2,3,
  4. Tao-Cheng Wu1,2,
  5. Shing-Jong Lin1,2,3,4,
  6. Jaw-Wen Chen1,2,4,5
  1. 1Division of Cardiology, Department of Internal Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
  2. 2Cardiovascular Research Center, National Yang-Ming University, Taipei, Taiwan
  3. 3Institute of Clinical Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan
  4. 4Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan
  5. 5Institute of Pharmacology, National Yang-Ming University School of Medicine, Taipei, Taiwan
  1. Correspondence to Professor Jaw-Wen Chen, Division of Cardiology, Taipei-Veterans General Hospital, No. 201 Sec. 2, Shih-Pai Road, Taipei, Taiwan; jwchen{at}vghtpe.gov.tw

Abstract

Background Increased oxidative stress and vascular inflammation have been demonstrated in patients with cardiac syndrome X (CSX). Bilirubin, once considered simply the metabolic end product of haem degradation, has emerged as a potential endogenous inhibitor of atherosclerosis. This study was conducted to evaluate the prognostic role of serum bilirubin in disease progression and clinical outcome in patients with CSX.

Methods A total of 108 consecutive CSX patients were enrolled. Serum bilirubin levels were examined from blood samples collected before coronary angiography. All patients were prospectively followed up for 5 years for the composite end point of total adverse events including death and non-fatal cardiovascular events (non-fatal myocardial infarction, ischaemic stroke, rehospitalisation for unstable angina, and coronary revascularisation).

Results There were 20 adverse events, including five deaths, five ischaemic strokes and 10 rehospitalisations for unstable angina during follow-up. Patients with adverse events had lower baseline serum bilirubin levels (p<0.001). All patients were stratified into high-bilirubin, normal-bilirubin and low-bilirubin groups. The patients in the high-bilirubin group had the lowest incidence of total adverse events (p=0.008) and non-fatal cardiovascular events (p=0.008). In a multivariate Cox regression analysis, serum bilirubin, in addition to age and basal superoxide generation of circulating mononuclear cells, was also an independent predictor of total adverse events (HR 0.002; 95% CI 0.000 to 0.520; p=0.028).

Conclusions In patients with CSX, baseline serum bilirubin level was associated with long-term outcomes. Serum bilirubin could be a predictive and protective biomarker for disease progression and the development of cardiovascular events in CSX patients.

  • Antioxidant
  • bilirubin
  • cardiac syndrome X
  • outcome
  • stroke
  • microvascular
  • syndrome X
  • oxidative stress

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Footnotes

  • Competing interests None declared.

  • Ethics approval This study was conducted with the approval of the Taipei Veterans General Hospital, Taiwan.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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