Q. ST Depression only on Recovery?
Although ST depression during exercise often persists into recovery, it may not manifest until exercise has been terminated. The reasons for this are still not clear but the phenomena have been studied by several investigations. ST depression occurring in recovery only has the same significance as exercise induced ST changes.
Time Course of ST Depression
It has long been recognized that when ST depression comes on early at low workloads the degree of ischaemia is likely to be more severe. It has long been taught, when ST depression comes on at high workloads, but resolves very quickly after exercise, it constitutes a false positive ST depression. However, it has been found that significant CAD was more common than not, at least in those who were referred for angiography. As might be expected, patients with early onset, late offset ST depression usually had severe disease. Group of patients with resting ST depression increased with exercise, was found to have severe disease. It has often been stated that these patients should not be tested because the results would include a large number of false positives.
This might be true if the patients are asymptomatic, but certainly does not pertain to those who have anginal chest pain. It must be cautioned that not all patients with rapid resolution of ST depression during recovery have normal coronary arteries.