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      Which method of left atrium size quantification is the most accurate to recognize thromboembolic risk in patients with non-valvular atrial fibrillation?

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          Abstract

          Background

          Left atrial (LA) size is a predictor of cardiovascular outcomes in patients in sinus rhythm, whereas conflicting results have been found in atrial fibrillation (AF). This study aims to: (1) Evaluate the accuracy of LA size to identify surrogate markers of an increased thromboembolic risk in patients with AF; (2) Assess the best method to evaluate LA size in this setting.

          Methods

          Cross-sectional study enrolling 500 consecutive patients undergoing transthoracic and transesophageal echocardiography evaluation during a non-valvular AF episode. LA size was measured on transthoracic echocardiography using several methods: anteroposterior diameter, area in four-chamber view, and volumes by the ellipsoid, single- and biplane area-length formulas. Surrogate markers of stroke were evaluated by transesophageal echocardiography: LA appendage (LAA) thrombus, LAA low flow velocities, dense spontaneous echocardiographic contrast and LA abnormality.

          Results

          Except for non-indexed anteroposterior diameter, increased LA size quantified by all the other methods showed a moderate to high discriminatory power to identify all the surrogate markers of stroke. A higher accuracy was observed for indexed LA area in four-chamber view (LAA thrombus: AUC = 0.708, CI 95% 0.644- 0.772, p<0.001; LAA low flow velocities: AUC = 0.733, CI 95% 0.674- 0.793, p<0.001; dense spontaneous echocardiographic contrast: AUC = 0.693, CI 95% 0.638- 0.748, p<0.001; LA abnormality: AUC = 0.705, CI 95% 0.654-0.755, p<0.001), indexed single-plane area-length volume (LAA thrombus: AUC = 0.701, CI 95% 0.633-0.770, p<0.001; LAA low flow velocities: AUC = 0.726, CI 95% 0.660-0.792, p<0.001; dense spontaneous echocardiographic contrast: AUC = 0.673, CI 95% 0.611-0.736, p<0.001; LA abnormality: AUC = 0.687, CI 95% 0.629-0.744, p<0.001), and indexed biplane area-length volume (LAA thrombus: AUC = 0.707, CI 95% 0.626-0.788, p<0.001; LAA low flow velocities: AUC = 0.737, CI 95% 0.664-0.810, p<0.001; dense spontaneous echocardiographic contrast: AUC = 0.651, CI 95% 0.578-0.724, p<0.001; LA abnormality: AUC = 0.683, CI 95% 0.617-0.749, p<0.001), without significant difference between them. Indexed LA area in four-chamber view and indexed area-length volumes also were independent predictors of surrogate markers of stroke.

          Conclusions

          Left atrium enlargement is associated with an increased prevalence of surrogate markers of stroke in patients with non-valvular AF. Indexed LA area in four-chamber view and indexed area-length volumes displayed the strongest association.

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          Most cited references 23

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          Left atrial size and the risk of stroke and death. The Framingham Heart Study.

          The medical literature contains conflicting reports on the association of left atrial (LA) enlargement with risk of stroke. The relation of LA size to risk of stroke and death in the general population remains largely unexplored. Subjects 50 years of age and older from the Framingham Heart Study were studied to assess the relations between echocardiographic LA size and risk of stroke and death. During 8 years of follow-up, 64 of 1371 (4.7%) men and 73 of 1728 (4.2%) women sustained a stroke, and 296 (21.6%) men and 271 (15.7%) women died. Sex-specific Cox proportional-hazards models were adjusted for age, hypertension, diabetes, atrial fibrillation, smoking, ECG left ventricular (LV) hypertrophy, and congestive heart failure or myocardial infarction. After multivariable adjustment, for every 10-mm increase in LA size, the relative risk of stroke was 2.4 in men (95% CI, 1.6 to 3.7) and 1.4 in women (95% CI, 0.9 to 2.1); the relative risk of death was 1.3 in men (95% CI, 1.0 to 1.5) and 1.4 in women (95% CI, 1.1 to 1.7). Adjusting for ECG LV mass/height attenuated the relation of LA size to stroke and death. After multivariable adjustment, LA enlargement remained a significant predictor of stroke in men and death in both sexes. The relation of LA enlargement to stroke and death appears to be partially mediated by LV mass.
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            Left ventricular diastolic dysfunction as a predictor of the first diagnosed nonvalvular atrial fibrillation in 840 elderly men and women.

            The objective of this study was to determine whether diastolic dysfunction is associated with increased risk of nonvalvular atrial fibrillation (NVAF) in older adults with no history of atrial arrhythmia. Few data exist regarding the relationship between diastolic function and NVAF. The clinical and echocardiographic characteristics of patients age > or =65 years who had an echocardiogram performed between 1990 and 1998 were reviewed. Exclusion criteria were history of atrial arrhythmia, stroke, valvular or congenital heart disease, or pacemaker implantation. Patients were followed up in their medical records to the last clinical visit or death for documentation of first AF. Of 840 patients (39% men; mean [+/- SD] age, 75 +/- 7 years), 80 (9.5%) developed NVAF over a mean (+/- SD) follow-up of 4.1 +/- 2.7 years. Abnormal relaxation, pseudonormal, and restrictive left ventricular diastolic filling were associated with hazard ratios of 3.33 (95% confidence interval [CI], 1.5 to 7.4; p = 0.003), 4.84 (95% CI, 2.05 to 11.4; p < 0.001), and 5.26 (95% CI, 2.3 to 12.03; p < 0.001), respectively, when compared with normal diastolic function. After a number of adjustments, diastolic function profile remained incremental to history of congestive heart failure and previous myocardial infarction for prediction of NVAF. Age-adjusted Kaplan-Meier five-year risks of NVAF were 1%, 12%, 14%, and 21% for normal, abnormal relaxation, pseudonormal, and restrictive diastolic filling, respectively. CONCLUSIONS; The presence and severity of diastolic dysfunction are independently predictive of first documented NVAF in the elderly.
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              Left atrial volume: important risk marker of incident atrial fibrillation in 1655 older men and women.

              To evaluate the contribution of left atrial (LA) volume in predicting atrial fibrillation (AF). In this retrospective cohort study, a random sample of 2200 adults was identified from all Olmsted County, Minnesota, residents who had undergone transthoracic echocardiographic assessment between 1990 and 1998 and were 65 years of age or older at the time of examination, were in sinus rhythm, and had no history of AF or other atrial arrhythmias, stroke, pacemaker, congenital heart disease, or valve surgery. The LA volume was measured off-line by using a biplane area-length method. Clinical characteristics and the outcome event of incident AF were determined by retrospective review of medical records. Echocardiographic data were retrieved from the laboratory database. From this cohort, 1655 patients in whom LA size data were available were followed from baseline echocardiogram until development of AF or death. The clinical and echocardiographic associations of AF, especially with respect to the role of LA volume in predicting AF, were determined. A total of 666 men and 989 women, mean +/- SD age of 75.2 +/- 7.3 years (range, 65-105 years), were followed for a mean +/- SD of 3.97 +/- 2.75 years (range, < 1.00-10.78 years); 189 (11.4%) developed AF. Cox model 5-year cumulative risks of AF by quartiles of LA volume were 3%, 12%, 15%, and 26%, respectively. With Cox proportional hazards multivariate models, logarithmic LA volume was an independent predictor of AF, incremental to clinical risk factors. After adjusting for age, sex, valvular heart disease, and hypertension, a 30% larger LA volume was associated with a 43% greater risk of AF, incremental to history of congestive heart failure (hazard ratio [HR], 1.887; 95% confidence interval [CI], 1.230-2.895; P = .004), myocardial infarction (HR, 1.751; 95% CI, 1.189-2.577; P = .004), and diabetes (HR, 1.734; 95% CI, 1.066-2.819; P = .03). Left atrial volume remained incremental to combined clinical risk factors and M-mode LA dimension for prediction of AF (P < .001). This study showed that a larger LA volume was associated with a higher risk of AF in older patients. The predictive value of LA volume was incremental to that of clinical risk profile and conventional M-mode LA dimension.
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                Author and article information

                Contributors
                Journal
                Cardiovasc Ultrasound
                Cardiovasc Ultrasound
                Cardiovascular Ultrasound
                BioMed Central
                1476-7120
                2014
                22 July 2014
                : 12
                : 28
                Affiliations
                [1 ]Cardiology Department, Coimbra’s Hospital and University Centre – General Hospital, Coimbra, Portugal
                [2 ]Faculty of Medicine, University of Coimbra, Coimbra, Portugal
                Article
                1476-7120-12-28
                10.1186/1476-7120-12-28
                4121510
                25052699
                Copyright © 2014 Faustino et al.; licensee BioMed Central Ltd.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

                Categories
                Research

                Cardiovascular Medicine

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