Unstable angina: ischaemia on resting ECG indicated a worse outcome.

Clinical bottom line (level 1b)

  1. Ischaemic changes on ECG at rest in patients who had an MI or unstable angina predicted an increased risk of death, or further MI or unstable angina (NNF = 14 for 2 years) .
  2. Changes on exercise or stress testing were not clearly helpful in predicting future outcome.
Moss et al: Journal of the American Medical Association 1993; 269 (18): 2379-2385
Expires July 2003

The study

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

Setting: 15 acute hospitals, USA, Canada, Israel

935 patients (aged mean 58 years, 76% male) acute coronary event (44% MI, 26% non-Q-wave MI, 30% unstable angina). MI- chest discomfort with ECG changes suggestive of acute coronary event and enzyme changes. unstable angina- increase in frequency or duration of typical angina symptoms plus transient ST or T wave changes on ECG; no enzyme elevation

Excluded if
  • CABG, angioplasty within one month
  • major co-morbidity- malignancy or severe hepatic, renal or cerebral disease
  • musculoskeletal disorders that preventing exercise testing
  • on cardiac glycosides or other drugs affecting ECG recording
  • bundle branch block, pacemaker, atrial fibrillation


    • Patients had exercise and stress testing 1 to 6 months after MI when they were considered to be clinically stable (mean 2.7 months).

    Multivariate analysis performed on risk factors identified during the test.

    100% followed for 6 months
    Outcomes studied:
  • cardiac death, MI, unstable angina

    • The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    cardiac death, MI, unstable angina 6 months 178/935 19.0%
    (16.5% to 21.6%)

    prognostic factor for
    cardiac death, MI, unstable angina     		time to outcome control rate (%) adjusted OR
    (95% CI)    		 NNF+
    (95% CI)
    ischaemia on rest ECG 2 years 178/935
    (19.0%)     		1.50
    (1.00 to 2.25)     		14
    (6 to inf)

    • No other risk factor was significantly associated with events.

    Comments

    1. Dr Moss and coworkers did not include in multivariable analysis the whole of the prognostic information that could have been included, which may explain apparent discrepancy with numerous reports which have established prognostic role for ambulatory or exercise electrocardiography or Thallium-201 scintigraphy.

    Citation

    1. Moss AJ, Goldstein RE, Hall J, et al: Detection and significance of myocardial ischemia in stable patients after recovery from an acute coronary event. Journal of the American Medical Association 1993; 269 (18): 2379-2385
    Contributor: Chris Ball and Clare Wotton, July 2000
    Reviewer: Andreas Michaelides

    Clinical Question.
    Patient unstable angina and MI
    Intervention or Exposure ischaemia on ECG
    Outcome death, MI or unstable angina