During a myocardial stress test, the heart is monitored via an ECG while patient is subjected to physical or pharmacological stress to detect ischemia. A positive result on the stress test is most commonly indicated by the presence of ST-segment depression, which suggests that there is insufficient blood flow to the heart muscle during exertion. Hyperacute T waves are typically indicative of hyperkalemia, prolongation of the PR interval generally indicates a first-degree AV block, and pathological Q waves are associated with a previous myocardial infarction rather than an acute ischemic event induced by stress.