Example of risk stratification with troponin and exercise ECG results
| Exercise ECG | Risk of cardiac death or MI at 5 months44 | |||||
|---|---|---|---|---|---|---|
| Result | Exercise ECG risk category44 | Troponin T ⩾ 0.2 μg/l | Troponin T 0.2–0.06 μg/l | Troponin T < 0.06 μg/l | ||
| Both low maximal workload achieved,and ST↓ ⩾ 0.1 mV in ⩾ 3 leads | High risk | 34% | 19% | 22% | ||
| Either a low maximal workload achievedor ST↓ ⩾ 0.1 mV in ⩾ 3 leads | Intermediate risk | 16% | 9% | 7% | ||
| Both a low maximal workload exceeded, and without ST↓ ⩾ 0.1mV in ⩾3 leads | Low risk | 5% | 7% | 1% | ||
| Unable to perform exercise ECG | 27% | 16% | 3% | |||
Evidence level IIb
Note: The confidence intervals for the quoted risk of cardiac death or myocardial infarction will be wide and may overlap for many of these categories. Furthermore, the results of troponins and exercise ECG tests are continuous rather than categorical variables, and should be interpreted accordingly. Thus these categories should be interpreted as indicating the general degree of cardiac risk, rather than a precise figure.
Definition: Low maximal workload achieved during exercise ECG. The definition of low maximal workload achieved was that below the 33rd centile of the distribution of the patients studied.44 These low workloads achieved on a bicycle ergometer were 90 W for men and 70 W for women. The approximate equivalents using the standard Bruce protocol on a treadmill would be less than stage II (⩽ 3.0 minutes).
Heavy shading = high risk; light shading = intermediate risk; no shading = low risk.