Takotsubo Cardiomyopathy Associated with Prolong QT Interval and Ventricular Tachyarrhythmia

C l i n M e d International Library Citation: Patel D, Patel R (2015) Takotsubo Cardiomyopathy Associated with Prolong QT Interval and Ventricular Tachyarrhythmia. Int J Clin Cardiol 2:028 Received: March 23, 2015: Accepted: April 10, 2015: Published: April 13, 2015 Copyright: © 2015 Patel D. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Patel and Patel. Int J Clin Cardiol 2015, 2:2 ISSN: 2378-2951


Introduction
Takotsubo Cardiomyopathy (TCMP), also known as apical ballooning syndrome or stress induced cardiomyopathy, is characterized by left ventricular mid and/or apical wall motion abnormality in the absence of obstructive coronary artery disease [1][2][3].TCMP is frequently precipitated by stressful events.The clinical presentation is often indistinguishable from acute coronary syndrome (ACS), and 2.2% of patients with an initial diagnosis of ACS are subsequently diagnosed with TCMP [2].EKG findings typically include ST, T wave changes and a prolonged QTc interval [2][3][4].Although, long QT is a typical finding of TCMP, it is certainly not diagnostic or pathognomonic.The natural history of TCMP is benign, and LV systolic dysfunction is usually reversible, requiring only supportive treatment until LV function normalizes [2].Here, we report a case of TCMP-associated with prolonged QTc interval associated with bradycardia, transient AV block and subsequent torsades de pointes (TdP).
She developed hypoxic respiratory distress requiring intubation within few hours of admission.Telemetry revealed non-sustained ventricular tachycardia.EKG showed widening of the QRS complex (122ms) with a left bundle branch block (LBBB) pattern, T wave inversion, and prolonged QTc interval.Troponin-I and CKMB peaked at 3.02ng/ml and 7.0ng/ml respectively.Based upon the above findings, immediate cardiac catheterization was done, which revealed normal coronary arteries and ventriculography showed an akinetic apex and mid ventricular portion and a hyperdynamic base, findings consistent with Takotsubo cardiomyopathy (TCMP).During cardiac catheterization, the patient developed transient complete heart block requiring temporary venous pacing.She was transferred to the coronary care unit where EKG showed reversal of the complete heart block but persistent bradycardia and associated prolonged QTc interval.Echocardiogram revealed left ventricular ejection fraction (LVEF) of 25% and wall motion abnormalities consistent with TCMP.
The progressively lengthening QTc interval resulted in an episode of ventricular tachycardia consistent with torsade de pointes (TdP) for which she received electronic cardioversion.Additionally, right ventricular pacing was initiated at the rate of 90-beats/minute and continued for two days.She was also given prophylactic lidocaine for ventricular tachycardia, which was discontinued the next day.
No more episodes of ventricular tachycardia developed while on temporary ventricular pacing.However, on day 2, she developed cardiogenic shock and required dopamine infusion and Intra-aortic balloon pump (IABP).IABP was also discontinued on day 4 and she was extubated on day 5. Repeat echocardiogram showed improvement in LV function (LVEF 35%).QTc interval was monitored throughout her hospital stay and it was normalized upon discharge.The patient remained symptoms free and LVEF was improved to 55% on repeat echocardiogram after 3 months.

Discussion
Patients with TCMP have T-wave inversion and QTc prolongation during the early phase, but they can last for several weeks [4].In a review of seven case series involving 180 cases, Bybee et al. reported a 1.5% incidence of ventricular arrhythmias among TCMP patients [3].TCMP can be considered a transient insult on myocardial repolarization caused by autonomic function disturbances and it causes TdP in presence of predisposing factors such as cardiac conduction anomalies, long QT, bradycardia, metabolic disease, medications, and genotype abnormalities.Case series of TCMPassociated TdP reported a higher incidence of TdP in male patients with prolonged QT interval.In this case series, most patients (80%) had one or more risk factors for TdP including bradycardia with or without atrioventricular block, congenital long QT syndrome, hypokalemia, use of amiodarone and dysopyramide [5].In our case, the patient's risk factors for TCMP-associated TdP included bradycardia and long QT.
Temporary ventricular pacing has been reported as an effective strategy for the treatment of TdP-associated with TCMP [5].However, right ventricular pacing can cause LV dysynchrony, leading to worsening of LV function [6].Indeed, in our case, the patient did not develop any episode of ventricular tachyarrhythmia on ventricular pacing but she developed cardiogenic shock requiring IABP in addition to vasopressors.
In patients with Takotsubo cardiomyopathy QTc interval prolongation is common and can last for more than two months.These patients should be discouraged to take medications that can prolong the QTc interval.While these patients are hospitalized, monitoring cardiac rhythm and electrolytes closely is critical to prevent ventricular arrhythmias.Further research is needed to elucidate which patients with prolonged QTc interval are at risk for TdP and to examine outcome of TCMP patients with prolonged QTc.