Myocardial Ischemia ECG Characteristics

Myocardial ischemia is a common manifestation of coronary artery disease and can be diagnosed through an electrocardiogram (ECG) by examining the ST segment and T wave changes. This condition is typically categorized into two types: endocardial ischemia and epicardial ischemia. In cases of epicardial ischemia, characteristic ECG findings include ST segment elevation and inverted T waves. The inverted T wave, often referred to as a "coronary T wave," is marked by symmetrical changes in both the descending and ascending limbs of the T wave.

ECG Features of Endocardial Ischemia

Conversely, endocardial ischemia typically presents with ST segment depression and flattened T waves. The most commonly observed patterns of ST depression include horizontal, downsloping, and sagging (or cup-shaped) configurations. These patterns are crucial for clinicians in diagnosing subendocardial ischemia and assessing the severity of myocardial stress.

Acute Ischemia and Ventricular Repolarization

QT Interval Changes

During acute ischemic events, the ECG may show a prolonged horizontal phase of the ST segment. This change reflects the impact of ischemia on ventricular repolarization, often resulting in alterations in the QT interval — either prolongation or shortening. These repolarization abnormalities are important indicators of myocardial instability and potential arrhythmogenic risk.

Clinical Management Based on ECG Findings

The severity of the patient's condition, along with the degree of ST segment elevation or depression, guides the treatment approach. Significant ST depression or persistent symptoms despite initial management necessitates urgent evaluation and intervention following the acute chest pain protocol. Timely recognition of these ECG patterns is essential for effective clinical decision-making and optimal patient outcomes.