Utility of P waves in exercise testing.
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Biomedical subjects
Publications and source records attributed to Myrvin H Ellestad.
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We evaluated the value of upsloping ST-segment depression in predicting the severity of myocardial ischemia. Comparison of the exercise electrocardiographic changes was made to myocardial perfusion images and coronary angiograms as the criteria for ischemia. We retrospectively reviewed 621 patients who underwent exercise technetium-99m tetrofosmin single photon emission computed tomography (SPECT) for the assessment of suspected or known coronary artery disease followed by coronary angiography within a 3-month period. The test sensitivity and specificity of 1 mm horizontal or downsloping ST depression in predicting reversible ischemia as assessed by gated SPECT imaging (GSI) were 65% and 87%, respectively. The corresponding values were 67% and 94% compared to coronary angiography. The sensitivity and specificity of gated SPECT imaging compared to coronary angiography were 78% and 89%. On the other hand when 1 mm upsloping ST depression at 70 ms past the J-point was regarded as abnormal, along with horizontal and downsloping, the sensitivity and specificity were 82% and 90% compared to myocardial perfusion imaging, and 77% and 92% as assessed by coronary angiography. We conclude that upsloping ST-segment depression is associated with an increased risk of coronary artery disease and is a valuable predictor of myocardial ischemia.
The aim of the study was to evaluate the utility of exercise-induced ECG changes in predicting the degree of myocardial ischemia as compared to angiographic and nuclear scintigraphic images. Four hundred and seventy one patients in whom exercise nuclear scintigraphy and coronary angiography revealed significant coronary narrowing (> or =70% luminal diameter narrowing) were studied. Down-sloping ST depression was found to be the best predictor of a large area of reversible ischemia (RI). Time of resolution of ST depression was the second most powerful predictor and the time of onset of ST depression was the third best predictor. RI on nuclear scintigraphy correlated better than angiographic findings with the ECG changes.
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