What does the QTc interval on an electrocardiogram (ECG) mean?

The electrocardiographic (ECG) parameter QTc—also known as the corrected QT interval—is an electrophysiological measurement derived from the ECG. It represents the total duration of ventricular electrical activity, extending from the onset of the Q wave to the end of the T wave, encompassing both depolarization and repolarization. A prolonged QTc interval generally suggests abnormal cardiac conduction, possibly indicating conduction block; however, interpretation must consider heart rate and other factors such as myocardial ischemia. If you experience chest tightness, it is advisable to consult a cardiologist for further evaluation. Additional diagnostic tests should be performed to identify the underlying cause, enabling selection of appropriate pharmacologic therapy.