Monday, March 23, 2009

Stress Test "Positive?"

For patients with AS, a stress test can be "positive." Here's what that means:

A Positive exercise test indicates symptoms, abnormal ST-segment response, or abnormal blood pressure response (less than 20-mm Hg increase) with exercise.

In one series,117 patients manifesting symptoms, abnormal blood pressure (less than 20-mm Hg increase), or ST-segment abnormalities with exercise had a symptom-free survival at 2 years of only 19 compared with 85% symptom-free survival in those with none of these findings with exercise. Four patients died during the course of this study (1.2% annual mortality rate); all had an aortic valve area less than 0.7 cm2 and an abnormal exercise test. In another series,118 exercise testing brought out symptoms in 29% of patients who were considered asymptomatic before testing; in these patients, spontaneous symptoms developed in 51% over the next year compared with only 11% of patients who had no symptoms on exercise testing. An abnormal hemodynamic response (e.g., hypotension or failure to increase blood pressure with exercise) in a patient with severe AS is considered a poor prognostic finding.117,125 Finally, in selected patients, the observations made during exercise may provide a basis for advice about physical activity. Exercise testing in asymptomatic patients should be performed only under the supervision of an experienced physician with close monitoring of blood pressure and the ECG.

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