Myocardial infarction: symptom-limited tolerance tests predicted ischaemia better than low level tolerance tests.

Clinical bottom line (level 4)

  1. In patients who had an uncomplicated myocardial infarction and had undergone low level exercise tolerance tests, a fifth showed positive signs of ischaemia.
  2. In patients who had undergone symptom limited tolerance tests, two fifths showed positive signs of ischaemia.
Jain et al: Journal of the American College of Cardiology 1993; 22: 1816-1820
Expires March 2003

The study

Setting: university hospital, USA

150 patients (aged range 26 to 93 years; mean 57, 73% male) myocardial infarction determined by the presence of a prolonged episode of chest pain with a typical increase and decrease in total creatine kinase-MB isoenzymes

Excluded if
  • death
  • spontaneous ischaemia at rest or during ambulation on the ward
  • complications
  • physician/patient preference


    • Medications judged necessary by the attending physician were continued.
    Independent blinded reference standard, applied in all patients from a consecutive appropriate spectrum.
    Reference standard:
    • no reference standard was given
    Diagnostic test: Exercise treadmill tests were performed with the patient in a fasting state using a modified Bruce protocol. Three minute stages beginning at 0% grade and 1.7 mph. The age-related peak heart rate was determined with standard criteria. A 12-lead ECG, heart rate and systolic and diastolic blood pressures were recorded in the supine and standing positions and after hyperventilation. These were recorded after 2 minutes in each stage and at peak exercise. Tests were evaluated for ST segment changes at two points: 1. heart rate at 70% of age-predicted maximum; 2. a symptom-limited end point. Test results were considered positive at the symptom limited end point if the peak heart rate was >10 beats/min more than the heart rate at 70% of age-predicted maximum. The exercise test result was considered positive if there was new = 1mm horizontal or downsloping ST segment depression at 0.08 s after the J point compared with baseline. The test was considered negative if the patient achieved a heart rate >85% of age-predicted maximum without = 1mm ST segment depression.
    • 57% of patients had a Q-wave MI.

    The evidence


    differential diagnosis number of patients prevalence
    (95% CI)
    positive result at low level end point 34 22.7%
    (16.0% to 29.4%)
    positive result at symptom-limited end point 60 40.0%
    (32.2% to 47.8%)

    • No serious adverse events occurred in either group.

    Citation

    1. Jain A, Myers H, Sapin PM, et al: Comparison of symptom-limited and low level exercise tolerance tests early after myocardial infarction. Journal of the American College of Cardiology 1993; 22: 1816-1820
    Contributor: Clare Wotton and Bob Phillips, January 2000
    Reviewer:

    Clinical Question.
    Patient myocardial infarction
    Intervention or Exposure symptom-limited exercise tolerance
    Comparison low level exercise tolerance
    Outcome diagnosis of inducible ischaemia