The electrocardiogram is most effective in detecting a decrease in which of the following?

Abnormalities in coronary blood flow resulting in ischemia of the ventricular muscle will lead to a current of injury, which is reflected as an upward or downward shift in the ST segment of the ECG recording. The electrical activity of the hea does not reflect changes in ventricular contractility, blood pressure, ejection fraction, or total peripheral resistance, although all of these can be altered by changes in coronary blood flow.