Hypocalcemia

Hypocalcemia causes prolonged QTc, ultimately predisposing to ventricular arrhythmias, particularly torsades des pointes. However, this is very uncommon and much less likely to occur with hypocalcemia compared to hypokalemia and hypomagnesemia. There have been cases of atrial fibrillation associated with prolonged QTc in the setting of hypocalcemia. The changes of hypocalcemia in prolonging the QT segment is unique in that the ST segment is prolonged and the T wave is virtually unchanged.

Examples:

Further Reading:

https://litfl.com/hypocalcaemia-ecg-library/

http://hqmeded-ecg.blogspot.com/search/label/hypocalcemia