Which of the following conditions is NOT associated with QT prolongation?

QT prolongation is a heart condition characterized by an extended time interval during the heart's electrical cycle. Certain electrolyte imbalances can lead to this prolongation, particularly those affecting potassium and magnesium levels.

In the context of the question, hypokalemia (low potassium) and hypomagnesemia (low magnesium) are both well-established causes of QT prolongation. These electrolytes are critical for proper cardiac electrical activity, and their deficiencies can disrupt repolarization, leading to a longer QT interval.

Hypocalcemia (low calcium) has also been associated with QT prolongation, primarily due to calcium's role in cardiac action potentials. A reduced level of calcium can affect the heart's ability to conduct electrical impulses properly, thus prolonging the QT interval.

On the other hand, hypercalcemia (high calcium) is not associated with QT prolongation. In fact, elevated calcium levels are more likely to shorten the QT interval. This is because hypercalcemia enhances myocardial contractility and may increase the heart rate, which typically results in a faster repolarization and, consequently, a shorter QT interval.

Therefore, hypercalcemia stands out as the condition that does not contribute to QT prolongation, making it the correct answer in this context