C53-25 Flecainide-Induced Cardiogenic Shock and Cardiac Arrest in an Elderly Patient on Anticoagulation

Abstract Introduction Flecainide, a class IC antiarrhythmic, is effective for atrial fibrillation but can cause severe proarrhythmia and myocardial depression, particularly in elderly patients or those with conduction disease, structural heart disease, or in cases of acute overdose. We report a case of profound bradyarrhythmia, cardiogenic shock, and cardiac arrest temporally associated with initial flecainide dosing. Case Description An 82 year old female with atrial fibrillation on apixaban became acutely unresponsive and diaphoretic at home after her first ever doses of flecainide (150 mg followed by 300 mg) prescribed earlier that day. EMS documented collapse with severe bradycardia; chest compressions were initiated with subsequent return of spontaneous circulation (ROSC). On ED arrival, she was cyanotic, unresponsive, saturating in the 80s on a 15 L non rebreather, and hypotensive. She was refractory to multiple doses of atropine and required transcutaneous pacing. Peripheral infusions of norepinephrine, dopamine, and epinephrine were started; mechanical CPR (LUCAS) and ACLS continued with multiple epinephrine doses and three sodium bicarbonate pushes. The patient was intubated; significant bright red blood was suctioned from the endotracheal tube. Emergent intraosseous access and a right femoral triple lumen catheter were placed. Vasopressin was added without hemodynamic improvement. An amiodarone bolus followed by infusion was initiated. Post ROSC ECG demonstrated a wide complex bradyarrhythmia. Initial ABG revealed combined metabolic and respiratory acidosis. Bedside ultrasound showed severely diminished cardiac output, bi atrial dilation, markedly dilated IVC and intrahepatic veins without respiratory variation, and minimal forward left ventricular flow. Additional push doses of epinephrine and sodium bicarbonate were administered. Given persistently incompatible hemodynamics, the family was counseled at the bedside regarding prognosis, and the patient was transitioned to comfort care measures only. Discussion The temporal relationship between first time high dose flecainide and the development of wide complex bradyarrhythmia, profound shock, and cardiac arrest suggests flecainide toxicity or proarrhythmia. Elderly patients are particularly susceptible due to reduced drug clearance, underlying conduction disease, and increased sensitivity to sodium channel blockade, which can cause QRS widening, bradyarrhythmias, and ventricular dysfunction. The echocardiographic findings and pressor-refractory shock are consistent with cardiogenic collapse. Bright red blood in the airway may reflect traumatic intubation or pulmonary hemorrhage in the context of anticoagulation and CPR. This abstract is funded by: none