What is the safety of treadmill stress testing in unstable angina?

Updated: Nov 21, 2018
  • Author: David Akinpelu, MD, FACP; Chief Editor: Eric H Yang, MD  more...
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Answer

Very little evidence exists with which to define the safety of early exercise testing in unstable angina. A review of this area found 3 studies covering 632 patients with stabilized unstable angina who had a 0.5% rate of death or MI within 24 hours of their exercise test. In addition, many available studies contain both patients with unstable angina and those who have experienced MI.

The limited evidence available supports exercise testing in patients with acute coronary syndrome who have appropriate indications once they are clinically stable. A study comparing a symptom-limited predischarge exercise test with a test performed at 1 month in patients with unstable angina or non–Q-wave infarction found that the 2 tests had similar prognostic value, but the earlier test identified additional patients who would experience events during the initial 1 month (these earlier events represented one half of all events occurring during the first year).

The Research on Instability in Coronary Artery Disease (RISC) study group examined the use of predischarge symptom-limited bicycle exercise testing in 740 men admitted with unstable angina (51%) or non–Q-wave MI (49%). The major independent predictors of 1-year infarction-free survival in multivariable regression analysis were the number of leads with ischemic ST-segment depression and the peak exercise workload achieved.

In 766 patients with unstable angina enrolled in the Fragmin During Instability in Coronary Artery Disease (FRISC) study between 1992 and 1994 who had both a troponin T level and a predischarge exercise test, the combination of a positive troponin T level and exercise-induced ST depression stratified patients into groups with a risk of death or MI that ranged from 1% to 20%.

In 395 women enrolled in FRISC I with stabilized unstable angina who underwent a symptom-limited stress test at days 5-8, risk for cardiac events in the next 6 months could be stratified from 1% to 19%. Important exercise variables included not only ischemic parameters such as ST depression and chest pain but also parameters that reflected cardiac workload. [20]


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