A high QTC interval on an electrocardiogram (ECG) is a significant medical finding that can indicate a variety of potential health issues. The QT interval represents the time from the start of the Q wave to the end of the T wave in the heart's electrical cycle, which corresponds to the time the ventricles take to depolarize and repolarize. A prolonged QT interval, often referred to as Long QT syndrome, can lead to serious arrhythmias and is associated with an increased risk of sudden cardiac death. In the context of an ECG, a high QTC (corrected QT interval) is typically corrected for heart rate to account for the fact that the QT interval can vary with the heart rate. A prolonged QTC can be congenital (inherited) or acquired (due to certain medications, electrolyte imbalances, or other conditions). It is important for healthcare professionals to identify a high QTC because it can be a sign of a potentially life-threatening condition that may require immediate medical attention and treatment. read more >>

Long QT syndrome is a heart rhythm disorder that can cause serious irregular heart rhythms (arrhythmias). ... In long QT syndrome, your heart muscle takes longer than normal to recharge between beats. This electrical disturbance, which often can be seen on an electrocardiogram (ECG), is called a prolonged QT interval.read more >>