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Exercise stress testing in special patient populations: acute coronary syndromes (myocardial infarction), women, elderly & revascularized
Clinicians should be familiar with the special challenges posed by some patient populations. The sensitivity, specificity, risks and results of the exercise test may be affected by patient characteristics. For example, exercising patients with ongoing myocardial ischemia may provoke life-threatening ventricular arrhythmias.
Patients with acute coronary syndromes (ACS) or acute myocardial infarction (AMI)
Exercise stress testing is routinely performed after acute myocardial infarction in order to assess presence of myocardial ischemia, evaluate angina pectoris, evaluate exercise performance, evaluate the effect of interventions and medications as well as prognosticate survival. However, exercise stress testing must not be performed within 4 to 6 days after acute myocardial infarction. Moreover, early exercise tests should not be maximal, which means that the clinician must set a lower goal regarding workload (e.g reaching 70% of maximal pulse instead of 85%). Many patients appreciate the exercise test because it offers them an opportunity to evaluate their performance and symptoms under the supervision of their clinician. Indeed, kinesiophobia (fear of exercising) is common after myocardial infarction and it is associated with poorer survival.
Patients with unstable angina pectoris with low risk (according to TIMI score or similar) may undergo stress testing when their clinical condition is stabilized. This usually takes 2 to 3 days and the patient must not have experienced chest pain during the last 12 hours before exercise. Patients with unstable angina pectoris with high risk should not undergo exercise stress test; these patients should be referred to angiography instead.
Exercise stress testing in women
Exercise ECG has lower sensitivity and specificity in women. This may be due to the following:
- Atherosclerosis is generally less severe in women.
- Women tend to have more difficulties reaching their maximal heart rate.
Exercise stress testing in elderly
Elderly also have difficulties reaching 85% of their maximal heart rate which hampers the utility of the stress test. However, elderly also tend to have more atherosclerosis (both in frequency and severity) which may compensate for inability to reach their maximal heart rate. Ultimately, the specificity of exercise stress testing is lower in elderly, as compared to younger individuals. Sensitivity, on the other hand, appears to be similar.
Exercise stress testing and revascularization (PCI, CABG)
Stress testing is commonly performed at various stages before and after revascularization procedures (PCI or coronary artery bypass grafting [CABG]). Stress testing is used to establish the diagnosis of ischemic heart disease as well as estimating the extent of ischemia. After revascularization procedures, stress testing is utilized to assess whether there is any residual ischemia or angina pectoris. Patients may undergo repeated stress tests to assess symptoms and signs of ischemia.