Unstable angina: previous beta-blockers and transient myocardial ischaemia increased the risk of an adverse outcome.

Clinical bottom line (level 2b)

  1. A fifth of patients with unstable angina had died, had a non-fatal MI or emergency revascularisation procedure before discharge.
  2. Patients with unstable angina were more likely to die, have a MI or an emergency revascularisation procedure if they had any of:
    • maintenance beta-blockers before admission (NNF = 5 for 6 days)
    • transient myocardial ischaemia (NNF = 5 for 6 days)
Patel et al: Heart 1996; 75: 222-228
Expires June 2003

The study

Inception cohort study with objective outcomes, adjusted for confounding factors, not validated in an independent set of patients.

Setting: three acute hospitals, UK

212 patients (aged range 30 to 75 years; mean 59, 80% male) presenting within 24 hours of an episode of typical anginal pain (either new onset, sudden exacerbation of previously stable angina or angina within one month of an MI; occurring at rest or on minimal exertion severe enough to require hospitalisation)

Excluded if
  • aged <30 or >70 years
  • prolonged chest pain
  • evolving Q waves on ECG
  • LVH with strain pattern, left bundle branch block or on drugs that might influence interpretation of ST segment changes



    • Factors studied:
  • death, MI or emergency revascularisation
  • transient myocardial ischaemia
  • maintenance beta-blockers before admission
  • ST depression on resting 12-lead ECG


    • All patients had aspirin 150 mg po and maximal antianginal treatment (iv nitrates, oral beta-blocker and oral diltiazem 60 mg twice daily). Patients were randomised to iv heparin (adjusted so aPTT 1.5 to 2.5), or no heparin.

    Multivariate regression analysis was performed to adjust for confounding factors.

    100% followed for until discharge (about 6 days)
    Outcomes studied:
  • death, non-fatal MI or emergency revascularisation

    • All patients had 48 hours of continuous ST segment monitoring.

    The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    death, non-fatal MI or emergency revascularisation until discharge (about 6 days) 41/212 19.3%
    (14.0% to 24.7%)

    prognostic factor for
    death, non-fatal MI or emergency revascularisation     		time to outcome control rate (%) adjusted OR
    (95% CI)    		 NNF+
    (95% CI)
    transient myocardial ischaemia 6 days 41/212
    (19.3%)     		2.94
    (1.14 to 7.54)     		5
    (2 to 47)
    maintenance beta-blockers before admission 6 days 41/212
    (19.3%)     		2.85
    (1.35 to 6.01)     		5
    (3 to 20)
    ST depression on resting 12-lead ECG 6 days 41/212
    (19.3%)     		2.11
    (0.93 to 4.82)     		7
    (-90 to 3)

    Comments

    1. T-wave changes were not studied.

    Citation

    1. Patel DJ, Holdright DR, Knight CJ, et al: Early continuous ST segment monitoring in unstable angina: prognostic value additional to the clinical characteristics and the admission electrocardiogram. Heart 1996; 75: 222-228
    Search Terms: unstable angina in Cochrane
    Contributor: Chris Ball and Clare Wotton, June 2000
    Reviewer: Thomas Mathew

    Clinical Question.
    Patient anginal pain, unstable angina
    Intervention or Exposure prognostic factors
    Outcome adverse outcomes, death, revascularisation procedures, MI