# Anterior Mitral Leaflet Flutter on M-mode Echocardiography as an Indicator of Atrial Fibrillation: Case Report

## TL;DR

This case report shows that fluttering of the anterior mitral leaflet on M-mode echocardiography can indicate atrial fibrillation, a finding not previously documented in emergency medicine literature.

## Contribution

The paper presents the first documented case in EM literature linking anterior mitral leaflet flutter on M-mode to atrial fibrillation.

## Key findings

- Anterior mitral leaflet flutter on M-mode echocardiography was observed in a patient with atrial fibrillation.
- The flutter was not due to aortic regurgitation or ischemia, but rather to atrial fibrillation.
- Emergency physicians can use this finding to improve rapid risk stratification of patients with chest pain.

## Abstract

M-mode in bedside point-of-care ultrasound (POCUS) transthoracic echocardiography (TTE) remains an important tool for emergency physicians. M-mode of the mitral valve is used to assess ejection fraction (EF) during assessment of E-point septal separation (EPSS). Anterior mitral leaflet fluttering visualized on M-mode echocardiography is a known sequela of aortic regurgitation. Although not previously reported in the emergency medicine (EM) literature, anterior mitral leaflet fluttering also occurs with atrial fibrillation.

We present the first case in peer-reviewed EM literature of anterior mitral leaflet fluttering observed on M-mode echocardiography caused by atrial fibrillation. Our patient was a 54-year-old male who had a POCUS TTE that showed anterior mitral leaflet fluttering on EPSS. Subsequent inpatient workup confirmed the diagnosis of symptomatic atrial fibrillation without ischemia or clinically significant aortic regurgitation.

Emergency physicians must rapidly assess and risk-stratify undifferentiated patients presenting with chest pain. Understanding that anterior mitral leaflet fluttering on M-mode during E-point septal separation may signal atrial fibrillation augments efficient and appropriate disposition of these patients.