Torsades de pointes related to transient marked QT prolongation following successful emergent percutaneous coronary intervention for acute coronary syndrome

We report 2 patients in whom transient marked QT prolongation occurred after successful emergent percutaneous coronary intervention (PCI) for acute coronary syndrome. One patient developed torsades de pointes. In both cases, the QT interval became markedly prolonged within 24 hours after PCI, and this prolongation persisted for 4 days. The T waves had a giant and bizarre negative shape with a prolonged T-wave peak to T-wave end interval. No new-onset ischemia or congenital long QT syndrome was related to the episodes. The patients had not taken any drugs that could have prolonged the QT interval, and their serum potassium levels were within normal limits. Torsades de pointes following successful PCI for acute coronary syndrome is uncommon, but acquired long QT syndrome should be considered and treated in patients in whom giant and bizarre negative T waves and QT prolongation develop after PCI.