Long QT syndrome and torsades de pointes complicating mitral valve replacement.

Severe QT interval prolongation >500ms occurs in one quarter of cardiac surgical patients in the perioperative period while moderate prolongation occurs in most of them. Prolonged QT interval may be associated with torsades de pointes and lead to sudden cardiac death. Because of the high incidence of prolonged QT in cardiac surgery patients and its perioperative adverse outcomes, it is vital to identify it early and take necessary precautions. We report and discuss the catastrophic events and management of two patients with long QT syndrome complicating mitral valve replacement.

Case vignette

Patients undergoing cardiac surgery are at high risk of developing long QT syndrome (LQTS) and torsades de pointes (Tdp). To reiterate the importance of QT interval prolongation in patients undergoing cardiac surgery, we report the case of two elderly gentlemen who underwent mitral valve replacement. These patients were treated with intravenous amiodarone in the perioperative period for atrial fibrillation. They developed LQTS and Tdp. Postoperative ECG of the first patient showed a ventricular premature complex and prolonged QT interval (673 ms) triggering ventricular fibrillation (Fig. 1A) and torsades de pointes (Fig. 1B). Holter study of the second patient showed multiple runs of polymorphic ventricular tachycardia with baseline corrected QT of 523 ms (Fig. 2). Amiodarone is a known offender for causing prolonged QT interval and tdp. In both the patients QT interval normalized with return of sinus rhythm and no further episodes of ventricular arrhythmia after correction of electrolytes and withdrawal of the offending drug. We conclude that in these groups of patients, QT interval should be scrutinized, adequate heart rate and electrolyte levels should be maintained, and offending drugs should be avoided to prevent catastrophic events.

Fig. 1

(A) ECG lead II shows a ventricular premature complex, prolonged QT interval leading to ventricular fibrillation. (B) ECG lead II shows torsades de pointes.

Fig. 2

Holter monitoring shows the runs of polymorphic ventricular tachycardia.

Conflicting of interest

The authors have none to declare.