Long-term (subacute) potassium treatment in congenital HERG-related long QT syndrome (LQTS2)

Potassium Treatment in LQTS2, Introduction: Congenital long QT syndrome (LQTS) is subdivided according to the underlying gene defect, In LQTS2, an aberrant HERG gene that encodes the potassium channel I-Kr leads to insufficient I-Kr activity and delayed repolarization, causing ECG abnormalities and torsades de pointes (TdP). Increasing serum potassium levels by potassium infusion normalizes the ECG in LQTS2 because I-Kr activity varies with serum potassium levels, Methods and Results: In an LQTS2 patient who presented with TdP, we attempted to achieve a long-term (subacute) elevation of serum potassium by increased potassium intake and potassium-sparing drugs, However, due to renal potassium homeostasis, it was impossible to achieve a long-lasting rise of serum potassium above 4.0 mmol/L. Conclusion: Although raising serum potassium reverses the ECG abnormalities in LQTS2 a long-lasting rise of serum potassium is only partially achievable because in the presence of normal renal function, potassium homeostasis limits the amount of serum potassium increase.