The case of a 74-year-old patient who experienced an electrical storm while being admitted to the intensive unit for acute hypercapnic respiratory failure. The patient had a history of atrial fibrillation and is on dofetilide. The electrical storm was characterized by multiple runs of polymorphic ventricular tachycardia, which was believed to be secondary to the use of dofetilide and later the usage of amiodarone. The patient was treated with lidocaine infusion, ICD reprogramming, and intravenous magnesium sulfate, which resulted in the successful termination of the tachycardia. This case highlights the necessary steps in the management of an electrical storm, the possible pro-arrhythmogenic effects of anti-arrhythmia medications, and the relative frequency of electrical storms in ICD recipients.

An electrical storm is defined by the occurrence of equal or more than three episodes of sustained ventricular tachycardia, ventricular fibrillation, or appropriate implantable cardioverter defibrillator shocks in a time span of 24 hours [1]. An electrical storm usually signifies a poor outcome in most patients. It is usually associated with hemodynamic compromise, multi-organ dysfunction, and eventually cardiac arrest; thus, it should be treated as a medical emergency [2].  There are a variety of ways to terminate an electrical storm. They include both pharmacologic and non -pharmacologic therapy, in our discussion we go into detail regarding the management of an electrical storm.

A 74-year-old female with a past medical history of severe chronic obstructive pulmonary disease, rheumatic mitral stenosis, mitral valve replacement, implantable cardioverter defibrillator implantation, atrial fibrillation s/p ablation, incomplete left atrial appendage occlusion device and non-ischemic cardiomyopathy presented to the emergency department because of shortness of breath and altered mental status. Physical examination and vital signs are unremarkable except for BP 99/53 and Body mass index- 34.39 kg/m². The patient was intubated and transferred to the critical care unit. She was started on steroids, antibiotics, bronchodilators, and her home dosage of furosemide, metoprolol, diltiazem, warfarin, and dofetilide was resumed.

Later during the day, runs of non-sustained ventricular tachycardia were noted on continuous telemetry. Dofetilide was discontinued and amiodarone was started. About 30 minutes later, she started having full-blown episodes of wide complex tachycardias, and she was given a lidocaine bolus of 1.5mg/kg and started on lidocaine drip at a rate of 1.5mg/minute, magnesium, and potassium infusion. Despite all these interventions, she continued to have multiple ICD shocks. The telemetry report electrocardiogram waveform was consistent with a torsade de pointe. The rate in the atrium was increased to 90 beats per minute and all anti-tachycardia pacing that had worsened the arrhythmia was turned off.  The IV lidocaine drip was increased to 2 mg/minute and magnesium was given. Furthermore, a magnet was also placed on her cardiac contractility modulation device, discontinued pantoprazole, and amiodarone. The electrical storm lasted about 2-3 hours and the patient was shocked about 25 times during this entire emergency.  After the interventions, the torsade de pointes resolved, and the patient was not shocked by the ICD throughout the night. 

Torsade de pointes (TdP) is a life-threatening arrhythmia that can occur in patients with predisposing factors such as long QT syndrome, electrolyte abnormalities, and drug-induced QT prolongation. TdP is characterized by a polymorphic ventricular tachycardia with a characteristic twisting pattern on the electrocardiogram (ECG). An electrical storm is defined as three or more episodes of sustained ventricular tachycardia or fibrillation within a 24-hour period. Electrical storms are associated with significant morbidity and mortality and require urgent management. Electrical storms are associated with an increased risk of hospitalization for heart failure, death and heart transplantation [2]. Electrical storms,which carry a poor prognosis are quite common in ICD recipients, 1 in every 5 ICD recipients experiences electrical storms [3].

Figure: Imaging of polymorphic ventricular tachycardia

Determining the mechanism of an electrical shock is crucial to treating the underlying substrate at the root cause of the disorder. Electrical storms can be classified under 3 categories: monomorphic ventricular tachycardias (VT), polymorphic VT or ventricular fibrillation. Electrolyte imbalances like hypokalemia and hypomagnesemia, hypothyroidism, and medications which prolong QT intervals like methadone, erythromycin, amiodarone, and proton pump inhibitors should also be monitored [14]. In this case, a 74-year-old female experiencing an electrical storm believed to be secondary to TdP. She was managed with a magnet placed on the cardiac contractility modulation device. The cardiac contractility modulation (CCM) device is a new technology that delivers non-excitatory high-frequency biphasic electrical signals to the heart during the absolute refractory period with the goal of improving its contractility. [7,8]. However, there are only a few studies/ case reports regarding CCM devices and ICDs interaction. The devices at risk of interaction with CCM devices are external cardioverter defibrillators and subcutaneous-ICDs [9]. The patient was initially on dofetilide, later switched to amiodarone when ventricular tachycardia (VT) runs were noted on telemetry. Amiodarone an antiarrhythmic drug, despite its efficacy, is associated with several adverse effects, including QT prolongation, which can lead to TdP. In patients with drug induced TdP, amiodarone was discontinued according to the current guidelines [4,5,6].  PPIs have also been associated with an increased risk of QT prolongation and TdP(10,11)and hypo magnesemia [12,13] which might have contributed to the worsening of the polymorphic ventricular tachycardia.  Discontinuing the PPI was one of the actions which led to the termination of the electrical storm.

 The management of an electrical storm involves identifying the precipitating factors like drugs that prolong QT intervals, a stat electrophysiology consult, ICD reprogramming, pharmacologic therapy depending on the mechanism of the ventricular tachycardia, as well as the management of underlying electrolyte abnormalities. The use of a magnet to deactivate the cardiac contractility modulating device may be a useful adjunct in the management of TdP, also identifying and discontinuing the medications that precipitate the electrical storm is crucial.