Unstable angina: certain clinical features predicted a worse outcome.

Clinical bottom line (level 1b)

  1. Patients with unstable angina who had the following risk factors were at increased risk of dying, having an MI or heart failure:
    • post MI (<14 days) (NNF = 4 for 2 unknown)
    • no beta-blocker or rate-lowering calcium channel blocker (NNF = 6 for unknown)
    • baseline ST depression (NNF = 9 for unknown)
    • requiring iv nitrate on admission (NNF = 12 for unknown)
    • diabetes mellitus (NNF = 13 for unknown)
    • increasing age (NNF = 31 for unknown)
Calvin et al: Journal of the American Medical Association 1995; 273 (2): 136-141
Expires July 2003

The study

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

Setting: coronary care unit, university hospital, USA

393 patients (aged mean 62 years, 57% male) unstable angina:
  • ischaemic type pain at rest, lasting >20 minutes, alleviated by nitrates, or with ST-T changes on ECG
  • presence of exertional angina increasing in frequency and duration at ecreasing levels of exercise


Excluded if
  • CK more than two times upper limit of normal, and Ck-MB fraction <0.05



    • Factors studied:
  • MI or death
  • post MI (<14 days)
  • no beta-blocker or rate-lowering calcium channel blocker
  • baseline ST depression
  • requiring iv nitrate on admission
  • diabetes mellitus
  • increasing age (per decade)


    • Majority of patients received aspirin and heparin. Patients had iv nitrate, beta-blockers and calcium channel blockers as required.

    Multiple regression analysis on risk factors.

    ?100% followed for until discharge
    Outcomes studied:
  • death or MI

    • The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    death or MI until discharge 30/393 7.6%
    (3.4% to 12%)

    prognostic factor for
    death or MI     		time to outcome control rate (%) adjusted OR
    (95% CI)    		 NNF+
    (95% CI)
    post MI (<14 days) ? 30/
    (7.6%)     		5.72
    (1.92 to 17.0)     		4
    (2 to 17)
    no beta-blocker or rate-lowering calcium channel blocker ? 30/
    (7.6%)     		3.83
    (1.55 to 9.42)     		6
    (3 to 27)
    baseline ST depression ? 30/
    (7.6%)     		2.81
    (1.45 to 5.47)     		9
    (4 to 33)
    requiring iv nitrate on admission ? 30/
    (7.6%)     		2.33
    (1.31 to 4.17)     		12
    (6 to 47)
    diabetes mellitus ? 30/
    (7.6%)     		2.19
    (1.25 to 3.83)     		13
    (6 to 58)
    increasing age (per decade) ? 30/
    (7.6%)     		1.48
    (1.21 to 1.90)     		31
    (17 to 69)

    Comments

    1. Short follow-up. Prognostic factors need to be validated in another set of patients before being more widely applied.
    2. Newer prognostic factors may be incorporated into such models to enhance utility.

    Citation

    1. Calvin JE, Klein LW, VandenBerg BJ, et al: Risk stratification in unstable angina: prospective validation of the Braunwald Classification. Journal of the American Medical Association 1995; 273 (2): 136-141
    Contributor: Nick Shenker and Chris Ball, July 2000
    Reviewer: Christian Torp-Pedersen

    Clinical Question.
    Patient unstable angina
    Intervention or Exposure Brunwald classification, clinical factors
    Outcome cardica complications, MI, death, revascularisation