Ragavendra R. Baliga, M.D
Assistant Professor
Division of Cardiology
University Of Michigan

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Question 31 of 39:

As this patient had a uncomplicated myocardial infarction, he should have symptom limited stress testing within two to three days of his acute myocardial infarction.

You clicked 'False'

Correct!

High-level exercise testing early after acute myocardial infarction is best avoided.

The basic aims of early exercise testing after MI are to

• assess functional capacity and the patient's ability to perform tasks at home and at work;
• evaluate the efficacy of the patient's current medical regimen; and
• risk-stratify the post MI patient according to the likelihood of a subsequent cardiac event.

After uncomplicated myocardial infarction, patients can be divided into relatively high- and low-risk groups for subsequent cardiac events if all the information available on the treadmill test is used.

Low-level exercise testing appears to be safe if patients have undergone in-hospital cardiac rehabilitation, including low-level exercise, have had no symptoms of angina or heart failure, and have a stable baseline ECG 48 to 72 hours before the exercise test.

Two different protocols have been used to determine the end points of these very early exercise tests:

• The traditional submaximal exercise test (done at 3 to 5 days in patients without complications) incorporates a series of end points, including a peak heart rate of 120 to 130 bpm or 70% of maximal predicted heart rate for age, a peak work level of 5 METs, or clinical or ECG end points of mild angina or dyspnea, ST-segment depression>2mm, exertional hypotension, or 3 or more consecutive premature ventricular contractions, whichever end point is reached first.
• The second protocol is performance of a symptom-limited exercise test (done at 5 days or later) without stopping for target heart rates or MET levels. Although this level appears to be safe and will result in higher frequency of abnormal exercise tests, the prognostic value of ST depression occurring at higher work levels in deconditioned patients is uncertain and may lead to unnecessary cardiac catheterization.