Atrial fibrillation, not atrial cardiopathy, is associated with stroke: A single center retrospective study

https://doi.org/10.1016/j.jns.2019.05.012Get rights and content

Highlights

  • Echocardiography data on 8679 patients was stratified based on left atrial enlargement (LAE).

  • Prevalence of atrial fibrillation increased with increasing size of left atrium (LA).

  • There was no association of LAE with increased risk of stroke.

Abstract

Background

Atrial fibrillation (AF) increases the risk of thromboembolism. Atrial cardiopathy, defined as structural left atrial enlargement (LAE), has been proposed to be a unifying risk factor for stroke, with or without atrial fibrillation (AF). We sought to understand the relative importance of LAE and AF as risk factors for stroke.

Methods

We performed a retrospective analysis of all patients who underwent echocardiography within the Henry Ford Health System between March and September 2016. Patients were categorized based on the degree of LAE (none, mild, moderate and severe). The diagnosis of prior stroke or AF was ascertained by the presence of these conditions in the electronic medical record (www.EPIC.com).

Results

Total of 8679 cases, 54% were female, 41% were African-American, and mean age was 65 ± 17 years. Fifteen percent had mild, 12% had moderate and 18% had severe LAE; the frequency of AF was 22%; and prior stroke was 18%. In multivariate analysis, the odds of AF increased progressively with severity of LAE (adjusted OR for mild 1.81, moderate 2.13 and severe 4.38, all P < .001) and AF was confirmed as a risk factor for prior stroke (aOR 1.34, CI 1.15–1.56, p < .001). By contrast, there was no association between LAE and stroke (aOR 0.98 CI 0.86–1.12, p = .74), regardless of the severity of LAE, and regardless of whether AF was present or not.

Conclusion

Structural LAE, found in almost half of this population, has a significant association with AF. While AF was confirmed to have a significant association with prior stroke, we found no association between stroke and LAE. AF, not LAE, appears to be the true atrial factor associated with stroke.

Introduction

Atrial fibrillation (AF) is a commonly diagnosed cardiac arrhythmia with an estimated prevalence of 49–96 cases per 1000 person-years. [1] AF increases the annual risk of thromboembolism to as high as 6%, which is about 7 times greater than seen with sinus rhythm [2]. AF is further associated with a four-fold increased prevalence of ischemic stroke, prompting an assessment for AF in all patients who present with stroke. [3,4]

Increased size of the left atrium, the prevalence of which is estimated to be about 32%, is associated with new onset AF. [[5], [6], [7]] Left atrial enlargement (LAE) has been reported as a risk factor for incident [[8], [9], [10]] and recurrent stroke [11,12], especially in cases of cryptogenic and cardioembolic stroke with documented AF. [[13], [14], [15]] The Cardiovascular Health Study data has called into question whether LAE is independently associated with stroke. [16] [17].

The significant stroke risk associated with AF is well documented, and while it is known that LAE is a risk factor for developing AF, it remains unclear to what extent structural atrial pathology may contribute to stroke risk in the absence of AF. Atrial cardiopathy, defined as left atrial enlargement (LAE) with associated structural and physiological changes, has been proposed to be the unifying risk factor for AF and cardioembolic stroke. Atrial cardiopathy is defined as LAE on echocardiography, increased p-wave terminal force in lead V1 (PTFV1) on electrocardiography, or increased serum levels of brain natriuretic peptide (NT-proBNP) [18,19].

The extent to which atrial cardiopathy is associated with stroke in the absence of AF has not been fully evaluated. In this study, we sought to better understand the relative associations of LAE and AF with stroke.

Section snippets

Study setting and population

This retrospective study was conducted between March 6th to September 6th, 2016 at Henry Ford Health System (HFHS) in South-East Michigan. The health system is composed of five acute care hospitals, four free-standing emergency departments, and over 38 outpatient facilities. All patients who underwent transthoracic echocardiography (TTE)within this period were included in the analysis, regardless of indication, and regardless of the clinical setting (i.e. inpatient versus outpatient). TTE were

Results

A total of 8679 cases were included in the study. Mean age was 65 ± 17 years with a range from 16 to 103; 54% were female and 41% were African American. Fifty-five percent of patients had normal LA size, 15% had mild, 12% had moderate and 18% had severe LAE. Age, hypertension, diabetes, congestive heart failure, peripheral vascular disease, atrial fibrillation, CHADS2-Vasc scores, lower ejection fraction, and use of antiplatelet and anti-coagulation medications were all significantly associated

Discussion

In this large retrospective cross-sectional study, we found that the LAE found on routine echocardiography is strongly associated with a previous diagnosis of AF. We also confirmed that AF is associated with a history of stroke. By contrast, structural enlargement of the left atrium, found in almost half of the population, had no association with stroke, regardless of its severity, and regardless of the presence or absence of AF. These findings challenge the concept of atrial cardiopathy as the

Conclusion

Presence of LAE found on routine echocardiography is strongly associated with prevalent AF. Structural LAE, found in almost half of the population, represents a significant increasing association with occult AF, however, AF, not LAE, appears to be the true atrial factor associated with stroke.

Acknowledgments

None.

Sources of funding

No funding was received for this study.

Disclosures

S.A.M. has received consulting fees from Biogen.

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