The chapter Interpretation of the ECG During Stress Testing reviews the electrocardiographic changes of ischemia during exercise testing. Normal ECG changes during exercise are reviewed and include the Ta wave of atrial repolarization which is directed in the opposite direction of the P wave. Its duration extends into the ST segment, resulting in a false positive exercise test in some patients. The type, severity and duration of ST depression predicts CAD severity and outcome. Downsloping ST depression is more ominous than horizontal which is worse than upsloping. As Ellestad has long posited, an abnormal ST segment response is >1 mm of downsloping and horizontal and >1.5 mm of upsloping ST depression. The 12 lead ECG leads most predictive of myocardial ischemia are leads V4-6, I, and aVR. ST elevation in leads without Q waves occurs secondary to transmural ischemia and localizes to the stenotic coronary artery.
The Impact of Changing Global Atherosclerosis Patterns on Stress Testing chapter reviews changes in cardiovascular death (CVD) mortality in developed and developing countries and its impact on exercise testing. Age-adjusted CVD mortality in the United States decreased by 75% between 1950 and 2014. Similar decreases have occurred in other developed countries. The causes of this decrease represent decreases in risk factor burden and improvement in medical and surgical care. With a decreasing burden of CVD in many countries patients are presenting for exercise testing with less severe coronary artery disease. CVD mortality in developing countries, however, including in India and China, is increasing. The wide availability and cost-effectiveness of exercise testing makes it an ideal first test for most patients being evaluated for CVD in both developed and developing countries. .
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