Critical Care Medicine-Neurologic Disorders>>>>>Arrhythmias and Pacemaker
Question 8#

You are called to bedside in the ICU to a 73-year-old female admitted with urosepsis and non-ST elevation myocardial infarction for evaluation of arrhythmia on telemetry. Her 12-lead ECG reveals intermittent torsades de pointes (TdP) and the patient is hemodynamically stable.

Which of the following statements is MOST correct?

A. Magnesium sulfate is the first-line agent in sustained TdP
B. Amiodarone prolongs QT interval and is considered low risk for TdP
C. Sotalol and verapamil are safe nodal blocking agents for patients at risk for TdP
D. Haloperidol, methadone, erythromycin, and procainamide are safe in patients at risk for TdP
E. Hyperkalemia is a risk factor for TdP

Correct Answer is B

Comment:

Correct Answer: B

Torsades de pointes (TdP) is a specific form of polymorphic VT characterized by a pattern of twisting points and is considered the acquired form of drug-induced long-QT syndrome (LQTS). Amiodarone prolongs QT interval, but it is considered to have a low risk for triggering TdP. Direct current cardioversion is the treatment of choice for sustained TdP or TdP that progressed to ventricular fibrillation. Verapamil is considered safe for patients with TdP, however sotalol has been associated with TdP and is listed as a drug that raises the risk of TdP. Likewise, haloperidol, methadone, erythromycin, and procainamide are known to increase the risk for TdP occurrence. Hypokalemia is a risk factor for TdP and should be corrected to a potassium level of 4.5 to 5.0 mmol/L in patients with TdP. Magnesium sulfate (2 g) can be infused to terminate TdP irrespective of the serum magnesium level, and repeat doses may be necessary. 

References:

1. Banai S, Tzivoni D. Drug therapy for torsade de pointes. J Cardiovasc Electrophysiol. 1993;4:206-210.
2. Zipes DP, Camm AJ, Borggrefe M, et al. ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: a report of the American College of Cardiology/American Heart Association task force and the European Society of Cardiology Committee for practice guidelines (writing committee to develop guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society. Circulation. 2006;114:e385- e484.
3. Drew BJ, Ackerman MJ, Funk M, et al. Prevention of torsade de pointes in hospital settings: a scientific statement from the American Heart Association and the American College of Cardiology Foundation. J Am Coll Cardiol. 2010;55:934-947.