Po-04-025 a perfect storm - refractory torsades in a patient with mitochondrial disease and severe hypothyroidism

Mitochondrial diseases (MD) such as Mitochondrial Encephalopathy, Lactic acidosis, And Stroke-like episodes (MELAS), Myoclonic Epilepsy with Ragged Red Fibers syndrome (MERRF) and Leber’s hereditary optic neuropathy are associated with ventricular pre-excitation and WPW. Refractory Torsades de Pointes (TdP) as a complication of MD or hypothyroidism is very rare We present a case of refractory TdP in a patient due to a combination of MD and severe hypothyroidism 39-year-old female with history of MELAS, Hashimato's thyroiditis, presented with syncope due to recurrent polymorphic VT. QTc on EKG was 535 ms. Previously, she had normal EKG's. Cardiac catheterization showed normal coronaries, but she suffered multiple VT/VF arrests and was defibrillated > 100 times. Amiodarone, magnesium, and lidocaine drips had no effect. She was placed on ECMO with an Impella. Deep sedation could not be achieved on dexmedetomidine and midazolam, and isoproterenol was ineffective. Echocardiogram showed EF < 15%. She then underwent stellate ganglion blocks with cessation of TdP. Her TSH was > 134 with undetectable free T4 due to medical noncompliance. Amiodarone was held due to long QT. Repeat echo two days later showed complete recovery of EF. She was decannulated a week later and underwent bilateral sympathectomy and a dual chamber ICD implant. After two weeks of IV levothyroxine, patient’s QTc returned to normal. Cardiac MRI was normal with no late enhancement. She was discharge on quinidine to suppress PVC's and NSVT. This patient presented with refractory TdP in the setting of acquired long QT syndrome. Although she has a history of MD, her baseline EKG’s were normal. Hypothyroidism is suspected to be the etiology of prolonged QT. MD’s affect tissues with high energy requirements including the heart and thyroid, and metabolic derangements can precipitate mitochondrial crises. We postulate this vicious cycle was responsible for her presentation. Furthermore, antiarrhythmics and anesthetics must be used with caution in such patients. Amiodarone has both mitochondrial and thyroid toxicity. Propofol is considered harmful in MD. Midazolam has a dose dependent toxicity profile. Beta-blockers, isoproterenol, and quinidine also have mitochondrial toxicity and should be used with caution. VT storm is rare in patients with MD and hypothyroidism. Management requires careful attention to traditional antiarrhythmic medications and anesthetics.