What ECG finding is associated with hypercalcemia?

Hypercalcemia is associated with a shortened QT interval on an ECG. Elevated calcium levels in the blood affect cardiac myocytes and can lead to alterations in their action potential duration. Specifically, hypercalcemia increases myocardial contractility and decreases the refractory period of the heart due to effects on ion channels involved in depolarization and repolarization processes.

The QT interval represents the time it takes for the heart's ventricles to depolarize and then repolarize. In cases of hypercalcemia, the increased calcium concentration accelerates this repolarization phase, leading to a decrease in the QT interval’s duration.

In contrast, a prolonged QT interval is typically seen with conditions such as hypocalcemia. Flat T waves are more indicative of ischemia or electrolyte imbalances like hypokalemia. ST elevation is commonly associated with acute myocardial infarction or other conditions affecting the heart muscle but is not a direct consequence of hypercalcemia. Therefore, the understanding of hypercalcemia's direct effect on cardiac electrical activity is key to recognizing the associated ECG finding of a shortened QT interval.