Introduction: A previously healthy, physically active 35-year-old female on oral contraceptives presented to the emergency department with acute onset dyspnea, tachycardia and cold sweats one hour prior to arrival. Emergency physician had high clinical suspicion for pulmonary embolism and ordered a CT Pulmonary Angiogram at the time of initial evaluation. While preparing for transport to radiology, patient experienced severe anxiety, stood from stretcher and had witnessed collapse, striking head on the floor. PEA arrest was documented; CPR initiated, and patient was intubated. Despite CPR, and 3 rounds of ACLS medications, patient remained pulseless. Limited bedside echocardiogram demonstrated dilated right ventricle. Decision was made to proceed with thrombolysis. Alteplase (tPA) was given as a 10mg bolus after 12 minutes of PEA followed by 90 mg infusion over one hour. Return of spontaneous circulation (ROSC) was documented within 3 minutes of bolus initiation. Massive bilateral pulmonary emboli and leg DVT were confirmed by follow-up CT pulmonary angiogram. CT of the head was unremarkable. In the post-resuscitative period, patient had transient poor perfusion, obstructive shock, and lactic acidosis, but all resolved with vasopressors support. Patient was extubated 12 hours later and eventually discharged home with preserved neurological status. Resolution of the clot burden and right ventricular dysfunction demonstrated on 72hour repeat echocardiogram. Of note, triple lumen femoral central line had to be placed emergently during tPA infusion due to lack of adequate peripheral IV access. Femoral arterial line also placed soon after its completion. No bleeding complications were observed. After 6 months patient was doing well without respiratory or cardiac symptoms. Pulmonary embolism is responsible for 200,000 death in US annually, it is a well recognized cause (4.8%) of cardiac arrest, most frequently presenting as PEA with poor prognosis and third of the death occurring within first hour of symptoms onset¹. Current guidelines unequivocally support use of thrombolytics in hemodynamically unstable pulmonary embolism. However, its use during cardiac arrest remains controversial and based on anecdotal reports with various agents and dose regimens used². The largest European randomized study (1050 patients enrolled)³ did not show mortality benefit of thrombolytic use in out-of hospital cardiac arrest patients. There is a standing concern for bleeding complications. The lessons from our case, with inherent limitations of case reports: 1. tPA can be successfully used in cardiac arrest for presumed PE even after unsuccessful CPR. 2. Even small bolus (10 mg in our case) can be efficient in relieving obstructive physiology (and perhaps improving microcirculation). 3. Invasive procedures such as central venous and arterial line placement can be done safely if absolutely indicated even during thrombolytics infusion. References: 1. Kurkciyan I et al. Pulmonary embolism as cause of cardiac arrest: presentation and outcome. Arch Intern Med 2000;160:1529-35. 2. Sheth A et al. Bolus thrombolytic infusion during prolonged refractory cardiac arrest of undiagnosed cause. Emerg Med J. 2006 March; 23(3): e19. 3. Bottiger B et al. Thrombolysis during resuscitation for out-of-hospital cardiac arrest. N Engl J Med 2008;359:2651-62.