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Cumulative risk assessment in unstable angina: clinical, electrocardiographic, autonomic, and biochemical markers
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  1. S Kennon1,
  2. C P Price2,
  3. P G Mills1,
  4. P K MacCallum3,
  5. J Cooper3,
  6. J Hooper4,
  7. H Clarke2,
  8. A D Timmis1
  1. 1Department of Cardiology, Barts and the London NHS Trust, London, UK
  2. 2Department of Clinical Biochemistry, Barts and the London NHS Trust, London, UK
  3. 3MRC Epidemiology and Medical Care Unit, Charterhouse Square, London, UK
  4. 4Department of Clinical Biochemistry, Royal Brompton Hospital, London, UK
  1. Correspondence to:
    Dr Simon Kennon, Cardiology Department, London Chest Hospital, Bonner Road, London E2 9JX, UK;
    srok{at}dircon.co.uk

Abstract

Objectives: To determine the incremental value of clinical data, troponin T, ST segment monitoring, and heart rate variability for predicting outcome in patients with non-ST elevation acute coronary syndromes.

Methods: Prospective cohort study of 304 consecutive patients. Baseline clinical and electrocardiographic data were recorded, serial blood samples were obtained for troponin T assay, and 48 hour Holter monitoring was performed for ST segment and heart rate variability analysis. End points were cardiac death and non-fatal myocardial infarction during 12 months’ follow up.

Results: After 12 months, 7 patients had died and 21 had had non-fatal myocardial infarction. The risk of an event was increased by troponin T > 0.1 μg/l, T wave inversion on the presenting ECG, Holter ST shift, and a decrease in the standard deviation of 5 minute mean RR intervals. Positive predictive values of individual multivariate risk were low; however, analysis of all multivariate risk markers permitted calculation of a cumulative risk score, which increased the positive predictive value to 46.9% while retaining a negative predictive value of 96.9%.

Conclusion: A cumulative approach to risk stratification in non-ST elevation coronary syndromes successfully identifies a group in whom the risk of cardiac death or non-fatal myocardial infarction approaches 50%.

  • unstable angina
  • risk stratification
  • risk markers
  • non-ST elevation acute coronary syndromes
  • AUC, area under the receiver operating characteristic curve
  • CABG, coronary artery bypass graft
  • CKMB creatine kinase MB fraction
  • ELISA, enzyme linked immunosorbent assay
  • FRISC II, Fragmin and fast revascularization during instability in coronary artery disease
  • PTCA, percutaneous transluminal coronary angioplasty
  • SDANN, standard deviation of 5 minute mean RR intervals
  • TIMI, thrombolysis in myocardial infarction

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