Left atrial appendage morphology in patients with suspected cardiogenic stroke without known atrial fibrillation.

Miika Korhonen,Mikko Taina,Otso Arponen,Pirjo Mustonen,Antti Muuronen,Ritva Vanninen,Pekka Jäkälä,Marja Hedman,Kazunori Toyoda

doi:10.1371/journal.pone.0118822

Abstract

The left atrial appendage (LAA) is the typical origin for intracardiac thrombus formation. Whether LAA morphology is associated with increased stroke/TIA risk is controversial and, if it does, which morphological type most predisposes to thrombus formation. We assessed LAA morphology in stroke patients with cryptogenic or suspected cardiogenic etiology and in age- and gender-matched healthy controls. LAA morphology and volume were analyzed by cardiac computed tomography in 111 patients (74 males; mean age 60 ± 11 years) with acute ischemic stroke of cryptogenic or suspected cardiogenic etiology other than known atrial fibrillation (AF). A subgroup of 40 patients was compared to an age- and gender-matched control group of 40 healthy individuals (21 males in each; mean age 54 ± 9 years). LAA was classified into four morphology types (Cactus, ChickenWing, WindSock, CauliFlower) modified with a quantitative qualifier. The proportions of LAA morphology types in the main stroke group, matched stroke subgroup, and control group were as follows: Cactus (9.0%, 5.0%, 20.0%), ChickenWing (23.4%, 37.5%, 10.0%), WindSock (47.7%, 35.0%, 67.5%), and CauliFlower (19.8%, 22.5%, 2.5%). The distribution of morphology types differed significantly (P<0.001) between the matched stroke subgroup and control group. The proportion of single-lobed LAA was significantly higher (P<0.001) in the matched stroke subgroup (55%) than the control group (6%). LAA volumes were significantly larger (P<0.001) in both stroke study groups compared to controls patients. To conclude, LAA morphology differed significantly between stroke patients and controls, and single-lobed LAAs were overrepresented and LAA volume was larger in patients with acute ischemic stroke of cryptogenic or suspected cardiogenic etiology.

Highlights

Stroke is the leading cause of long-term disability and a major consumer of health care resources in both Western society and worldwide [1]
162 consecutive patients who were evaluated by neurologists and had acute ischemic stroke of cryptogenic or suspected cardiogenic etiology without previously reported Atrial fibrillation (AF) and without AF diagnosed at the time of enrollment were recruited
A total of 51 patients were excluded after recruitment for the following reasons: confirmed small vessel disease or carotid/vertebral artery stenosis (n = 38), cardiac computed tomography (cCT) image quality inappropriate for left atrial appendage (LAA) morphology analysis (n = 4), ECG synchronization failed (n = 3), contrast media injection failed (n = 2) or was contraindicated due to renal insufficiency (n = 1), and refusal to participate despite previously giving informed consent (n = 3)

Summary

Introduction

Stroke is the leading cause of long-term disability and a major consumer of health care resources in both Western society and worldwide [1]. Atrial fibrillation (AF), either chronic or paroxysmal (PAF), is the most common causes of cardioembolic stroke [2]. Over 90% of cardiac thrombi are formed in the left atrial appendage (LAA) in patients with non-rheumatic AF [3]. Defining the direct source of embolism is often difficult and requires various imaging modalities [4] and rhythm monitoring. Three-week telemetry has revealed PAF in almost 20% of cryptogenic stroke cases, whereas only 4–8% of AF has been detected with 48-hour monitoring [5,6]. AF and PAF may enlarge the LAA [7,8], and remodeled LAA structures may predispose an individual to atrial arrhythmias [9]. Certain LAA morphology type may affect rheology, flow velocity and coagulation tendency [10]. The recognition of morphological signs indicative of latent PAF and susceptibility to thrombus formation would be helpful

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