Abstract 15689: Resistant Rapid Atrial Flutter With Left Atrial Thrombus: A Therapeutic Dilemma

Abstract

Introduction: Electrical cardioversion (ECV) is highly successful in the treatment of typical atrial flutter (AFL). Patients with AFL with a rapid ventricular rate (RVR) of ≥150 beats per minute (BPM) and significant hemodynamic compromise benefit from urgent CV. This is a unique case of managing chemically resistance AFL with a left atrial (LA) thrombus. Case Presentation: A 48-year-old male with medical history of bioprosthetic mitral and aortic valve was admitted for new onset AFL with RVR. Patient complain of (c/o) progressively worsening dyspnea and chest palpitation from 3 days. The patient denied chest pain, dizziness, diaphoresis. On admission blood pressure (BP) was 122/80 mmHg with heart rate (HR) of 158 BPM. ECG showed 2:1 block AFL with RVR. Patient was started on IV heparin and diltiazem drip. However, as the HR remained >150 and patient continued to c/o palpitations, IV amiodarone was added. The BP started to fall with the HR still >150 BPM. An emergent TEE done showed LA thrombus. Hence, the ECV was not performed. Instead a synchronized (sync) 3-joule (J) shock on R wave was attempted to induce atrial fibrillation (AF), to achieve better rate control. Immediately after delivering the shock the cardiac rhythm was successfully converted to AF with HR of <80 BPM. Discussion: LA thrombus and clinical thromboembolic events are highly prevalent in AFL. TEE is usually done to exclude thrombus in a patient with AFL for >48 hrs and if presence of thrombus cannot be confidently excluded on TEE, CV should not be performed. As a shock provided during the relative refractory period (RRP) of the ventricle corresponding to the latter part of the T wave, can possibly induce ventricular fibrillation (the so-called “R-on-T Phenomenon”), with similar concept a low voltage sync shock on R wave, the RRP of the atria can possibly induce AF. AF can be more easily rate controlled on antiarrhythmics compared to AFL and a patient with LA thrombus on anticoagulants is at lower risk from embolic events in AF than SR. Conclusions: This clinical noninvasive maneuver may be useful and desired in the management of a deteriorating patient with AFL not responsive to chemical rate control and LA thrombus such as ours or for an instance when AF in a patient with LA thrombus was inadvertently converted to SR.