J Cardiovasc Ultrasound. 2016 Mar;24(1):20-27. English.
Published online Mar 24, 2016.
Copyright © 2016 Korean Society of Echocardiography
Original Article

Incremental Value of Left Atrial Global Longitudinal Strain for Prediction of Post Stroke Atrial Fibrillation in Patients with Acute Ischemic Stroke

Darae Kim, MD,1 Chi Young Shim, MD, PhD,1 In Jeong Cho, MD,1 Young Dae Kim, MD, PhD,2 Hyo Suk Nam, MD, PhD,2 Hyuk-Jae Chang, MD, PhD,1 Geu-Ru Hong, MD, PhD,1 Jong-Won Ha, MD, PhD,1 Ji Hoe Heo, MD, PhD,2 and Namsik Chung, MD, PhD1
    • 1Cardiology Division, Severance Cardiovascular Hospital, Yonsei University College of Medicine, Seoul, Korea.
    • 2Department of Neurology, Yonsei University College of Medicine, Seoul, Korea.
Received November 12, 2015; Revised January 25, 2016; Accepted February 01, 2016.

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background

Atrial fibrillation (AF) is a well-established risk factor for stroke. Interestingly, ischemic stroke increases risk of incident AF in patients without prior diagnosed AF. For better risk stratification for post-stroke AF, we studied left atrial (LA) size and mechanical function using two-dimensional (2D) speckle tracking imaging in patients with acute ischemic stroke.

Methods

A total of 227 patients (132 males, age 67 ± 12) with acute ischemic stroke without a history of AF underwent 2D transthoracic echocardiography and speckle tracking imaging for the assessment of LA volume index and global LA longitudinal strain (LALS). From clinical variables, the CHA2DS2-VASc score and National Institute of Health Stroke Scale (NIHSS) were calculated in each patient. Post-stroke AF was defined as newly diagnosed AF during the course after ischemic stroke.

Results

Post-stroke AF occurred in 25 patients (11%). Patients with post-stroke AF were older and showed a higher tendency of CHA2DS2-VASc score, significantly higher log NIHSS, larger LA volume index and lower global LALS than those without. In multivariate analysis, global LALS was an independent predictor for post-stroke AF (hazard ratio 0.90, 95% confidence interval 0.83.0.97, p < 0.01) after controlling for confounding factors. Furthermore, global LALS provided incremental predictive value for post-stroke AF over the CHA2DS2-VASc score, NIHSS, and LA volume index. The global LALS < 14.5% better distinguished post-stroke AF (area under the curve 0.837, sensitivity 60%, specificity 95%, p < 0.01) than CHA2DS2-VASc score.

Conclusion

Global LALS as a marker of LA mechanical function has incremental predictive value for post-stroke AF in patients with acute ischemic stroke.

Keywords
Atrial fibrillation; Stroke; Left atrium; Strain

Introduction

Atrial fibrillation (AF) is the leading cause of stroke.1) However, a few studies suggest that some of AF may be a result from stroke. Previous studies reported paroxysmal or asymptomatic AF after acute ischemic stroke had already occurred, in patients without previous history of AF. Incidental impairment of autonomic nervous system, which is reported in upto 40% of acute ischemic stroke patients, may trigger a new onset AF.2), 3), 4), 5) Also, various cardiovascular diseases accompanied with stroke could attribute to arrhythmogenic remodeling of left atrium (LA), promoting AF.6), 7)

AF in acute ischemic stroke patients is associated with higher in hospital mortality and poorer neurological outcomes. More severe neurologic deficits with higher recurrence rates have been reported in stroke patients with AF.8) Therefore, identification of post stroke AF in patents without previous history of AF is important as appropriate anticoagulation could reduce recurrences rates of stroke. However, due to often paroxysmal and asymptomatic nature of AF, patients with post stroke are often underdiagnosed. Also, no consensus has been made for efficient strategies to detect post stroke AF. The 24-hr electrocardiograph (ECG) recording is most often used to screen for AF, however, the sensitivity is relatively poor, detecting previously undocumented AF in only about 2–10.7% of acute ischemic stroke patents.9), 10), 11), 12) Although longer periods of monitoring increases detection rates of post stroke AF, not all patients can undergo extended rhythm monitoring in real world. Therefore, establishing adequate risk stratification tool to select high risk group to undergo extended monitoring could be cost effectively improve detection rate of post stroke AF.

The global LA longitudinal strain (LALS) assessed by two-dimensional (2D) speckle tracking transthoracic echocardiography (TTE) is a relatively simple and reproducible technique, which measures deformation of LA to assess LA function.13) Recent studies have shown that global LALS is well associated with AF recurrences after ablation or cardioversion of AF.14), 15), 16), 17)

In this study, we aimed to investigate if clinical and echocardiographic parameters were associated with post stroke AF in acute ischemic stroke patients without previous history of AF, by comprehensive evaluation of stroke severity and LA structure and function using 2D speckle tracking imaging.

Methods

Study subjects

We analyzed a retrospective cohort of 279 patients with acute ischemic stroke who were referred to the cardiology division for transesophageal echocardiography (TEE) from April 2012 to June 2013. All patients underwent TTE and TEE, as a part of a standard evaluation for the detection of cardioembolic sources within one week of the initial stroke. Ischemic stroke was confirmed by a focal neurologic deficit of sudden onset and magnetic resonance imaging findings. Patients with a transient ischemic attack and negative imaging findings were excluded. Patients who had significant valvular dysfunction to a moderate or severe degree, previous history of valve repair, valve replacement, cardiomyopathy, AF, supraventricular tachycardia, or radiofrequency ablation on the LA were not included in this study. Finally, the stored images were analyzed in 227 acute ischemic stroke patients without previous history of AF who presented with sinus rhythm at time of admission.

Patient clinical data, including history of hypertension, diabetes mellitus, cigarette smoking, dyslipidemia, a previous cerebrovascular accident, AF, onset of stroke, and neurologic examination including National Institute of Health Stroke Scale (NIHSS) score were determined at the time of admission. The diagnosis of previous persistent and paroxysmal AF was made on the basis of patient recall or by documentation of the arrhythmia on a previous ECG or medical record when available. The subtypes of ischemic stroke were classified according to the Trial of Org 10172 in Acute Stroke Treatment criteria by neurologists.18)

Every patient underwent immediate and continuous ECG monitoring for at least 3 days after admission. After discharges, patients underwent 24-hr ECG from outpatient clinics if patients complained symptoms of palpitation. Post stroke AF was defined as newly diagnosed AF after acute ischemic stroke in a patient.

Risk of post stroke AF was assessed using the CHA2DS2-VASc score, which assigns one point for congestive heart failure within the past 3 months or left ventricular (LV) ejection fraction < 40%; one point for hypertension; two points for age > 75 years; one point for diabetes; two points for stroke, transient ischemic attack, or systemic embolism; one point for vascular disease (prior myocardial infarction and peripheral arterial disease); one point for age 65 to 74 years; and one point for female sex.19) The two points derived from the acute embolism vent causing the present admission were not added to the patient.

Conventional transthoracic echocardiography

Each patient underwent a comprehensive transthoracic echocardiographic study using a Vivid 7 or Vivid 9 cardiovascular ultrasound system (GE Medical Systems, Horten, Norway), equipped with 2.5–3.5 MHz phased-array sector probes. During echocardiography, a one-lead ECG was recorded continuously. Standard 2D and Doppler measurements were performed per the recommendations of the American Society of Echocardiography guidelines. For the assessment of LA volume, apical four-chamber and two-chamber views were obtained. Maximal LA volume was measured manually using Simpson's methods at the end of ventricular systole and indexed to the body surface area.20)

Pulsed Doppler echocardiography of the transmitral flow was performed. The sample volume was positioned at the level of the mitral tips in the apical four-chamber view. Images were recorded at a speed of 50 to 100 mm/sec. From the transmitral recording, the peak early (E) and late diastolic filling velocities were obtained. An apical four-chamber view was also used to obtain Doppler tissue imaging of the mitral annulus. Sample volumes were placed on the septal side of the mitral annulus. Values shown for systolic, peak early (e'), and late diastolic annular velocities were obtained.

Speckle tracking echocardiography

Each patient underwent a 2D speckle echocardiography of the LA. Three consecutive cardiac cycles were recorded and averaged, and the frame rates were set to 60 to 80 frames/sec. The cardiac cycle was demarcated by indicating QRS onset and QRS complex used as the first reference frame. The analysis was performed offline using customized software (EchoPAC PC; GE Medical Systems). The LA echocardial border was manually traced in both four-chamber and two-chamber views. Because two segments of the LA roof demonstrated a lower longitudinal strain curves than those of the other four, they were excluded from both the four-chamber and the two-chamber views.21), 22) Therefore, global peak LALS during the ventricular systole was then measured by averaging the values obtained in the eight other LA segments. The time to peak LALS is also measured as the average of the eight segments and by calculating the time delay from the QRS to the positive peak LALS.

An experienced cardiologist, who was unaware of the patients' information, analyzed all echocardiographic values. The intra-observer and inter-observer reproducibility for the assessment of global LALS were determined by the Bland-Altman analysis. Intra-observer reproducibility was determined by repeating the strain measurements at two different time points by one experienced reader in 15 randomly selected patients. A second experienced reader performed the strain analysis in the same 15 patients, providing the inter-observer data. The Bland Altman analysis and intra-class correlation coefficient (ICC) showed good intra-and inter-observer agreement for global LALS. For inter-observer agreement of global LALS, the mean difference was 1.7 (-1.3, 4.4) and the ICC was 0.88; for intra-observer agreement, the mean difference was 1.2 (-2.0, 3.1) and the ICC was 0.90.

Transesophageal echocardiography

Each patient underwent comprehensive TEE immediately after the TTE by using a 5- to 7-MHz multiplane probe positioned at the appropriate level within the esophagus. All examinations were recorded on digital video in real time for display and evaluation. The TEE images were independently reviewed by two experienced cardiologists.

The multiple standard tomographic planes were imaged and LA appendage (LAA) emptying velocity, the presence of LA or LAA thrombi, presence of patent foramen ovale, and the severity of spontaneous echo contrast (SEC) in the LA or LAA were determined. Peak LAA emptying velocities were measured using pulsed Doppler by placing the sample volume approximately 1 cm inside of the orifice of the LAA.23) The peak emptying wavelets were measured in three consecutive cycles, and the maximal velocities were then averaged. An LA or LAA thrombus was diagnosed by the presence of an echo-dense mass in the LA or LAA, distinct from the endocardium and the pectinate muscles of the LAA.24) The SEC was diagnosed by the presence of characteristic dynamic smoke-like swirling echo in the LA or LAA, distinct from the background white noise due to excessive gain.25) The severity of the SEC was classified into one of the four grades on the basis of appearance and density as follows: none, mild (minimal echogenicity detectable only with optimal gain settings transiently during the cardiac cycle), moderate (a dense swirling pattern during the entire cardiac cycle), or severe (intense echogenicity and very slow swirling patterns in the LA or LAA, usually with a similar density in the main cavity).26)

Statistical analysis

Continuous variables were presented as a mean ± standard deviation and categorical variables as absolute and relative frequencies (%) of the group total. Comparisons between groups were performed using χ2, Kruskal-Wallis, or Mann-Whitney U tests. We constructed the receiver operating characteristic (ROC) curves to determine the diagnostic ability of global LALS and CHA2DS2-VASc score for post stroke AF. The performance of the predictive selected parameters was assessed using the area under the ROC curve and diagnostic performances were compared by means of the Delong tests.27) Associations between clinical/echocardiographic parameters and post stroke AF were assessed using univariate and multivariate logistic regression analyses. Variables selected for entry into the analysis were those with p < 0.1 on the univariate analysis and important variables in previous studies. The incremental predictive value of the global LALS for post stroke AF was assessed in three modeling steps. The first step consisted of CHA2DS2-VASc, a composite risk from the clinical variables. Then, NIHSS and LA volume index were added sequentially. The model χ2 value was used to determine whether there was a difference between various nested models for predicting the end point. The incremental value was assessed by comparing the global χ2 value for each parameter. The prognostic value of global LALS was determined using the Cox proportional-hazards model. A two-sided p value < 0.05 was accepted as indicating statistical significance. All data were analyzed using IBM SPSS Statistics for Windows version 21.0 (IBM Corp, Armonk, NY, USA).

Results

Clinical characteristics

Post stroke AF occurred in 25 patients (11%) during mean follow up of 23 ± 8 month. Table 1 shows baseline clinical characteristics of patients with or without post stroke AF. Patients with post stroke AF were significantly older than those without post stroke AF (p < 0.01). There was no statistically significant difference in the distribution of gender or comorbidities. The median value of CHA2DS2-VASc score did not differ between two groups. The NIHSS score was significantly higher in patients with post stroke AF.

Table 1
Clinical characteristics

Echocardiographic characteristics

Echocardiographic parameters are described in Table 2. The LA volume index and global LALS were significantly different between two groups. Patients with post stroke AF were presented with significantly higher LA volume index and lower global LALS. The LV ejection fraction and LV diastolic function, reflected by E/e', did not show significant difference.

Table 2
Echocardiographic characteristics

Clinical and echocardiographic factors in association with post stroke AF

The global LALS < 14.5% identified post stroke AF with are under curve of 0.837 (sensitivity = 60%, specificity = 95%). The ROC analysis showed comparable value for LA volume index > 32 mL/m2 with area under cover of 0.752 (sensitivity = 76%, specificity = 69%) with no significant difference for diagnostic performance (p = 0.42). Global LALS showed significantly better predictive value for post stroke AF (p = 0.02) than that of CHA2DS2-VASc (area under the curve = 0.612, sensitivity = 76%, specificity = 45%, p = 0.07) (Fig. 1). The global LALS, LA volume index, log NIHSS and CHA2DS2-VASc ≥ 4 were significantly related to occurrence of post of AF. The global LALS provided incremental predictive values for post stroke AF over combination of clinical variables (CHA2DS2-VASc, log NIHSS) and LA volume index (Fig. 2). From multivariate analysis, only the global LALS was significantly associated with post stroke AF (hazard ratio 0.90, 95% confidence interval 0.83–0.97, p < 0.01) (Table 3).

Fig. 1
Diagnostic performances of global LALS and CHA2DS2-VASc score for post stroke AF. LALS: left atrial longitudinal strain, AF: atrial fibrillation.

Fig. 2
Incremental value of global LALS for diagnosis of post stroke AF. The addition of LALS to the model on the basis of CHA2DS2-VASc score, log NIHSS, and LAVI resulted in significant improvement in the diagnostic value for stroke. LALS: left atrial longitudinal strain, AF: atrial fibrillation, NIHSS: National Institute of Health Stroke Scale, LAVI: left atrial volume index.

Table 3
Univariate and multivariate analysis for prediction of post stroke AF

Discussion

To our knowledge, this is the first study to investigate global LALS for prediction of post stroke AF in patients with acute ischemic stroke. The principal findings in the present study are that impaired mechanical function of LA assessed by 2D TTE with speckle tracking imaging could provide incremental value for predicting post stroke AF in patients with acute ischemic stroke. Therefore, an earlier awareness for high risk patients may improve further detections of post stroke AF, which can lead to appropriate anticoagulation to reduce recurrent stroke.

CHA2DS2-VASc score and global LALS for predicting post stroke AF

Patients with acute ischemic stroke are associated with substantially increased risk of AF. According to previous meta-analysis, 24% of patients with stroke or transient ischemic attack could be diagnosed with post stroke AF.12) Detection of post AF is vital because anticoagulation dramatically reduce risk of stroke recurrence by two-thirds.28) The decision rates of post stroke AF increase with longer and more sequential monitoring of rhythm along with more sophisticated methods, such as implanted loop recorders. However, considering costs and compliance of patients, not all patients with acute ischemic patients could undergo extensive screen of post stroke AF. Therefore, identification of high risk patents for post stroke AF during the course after acute ischemic stroke is important to prevent recurrent stroke. But there are few strategies to establish absolute risk of post stroke AF in patients with acute ischemic stroke with no previous history of AF.

CHA2DS2-VASc score is well validated risk model to estimate the risk of systemic thromboembolism or stroke in patents with AF, which composed of only clinical variables without echocardiographic parameters. Risk factors assigned in CHA2DS2-VASc score are also associated with prevalence of AF.29) Recent studies consistently demonstrated association of AF with advanced age, gender, hypertension, heart failure, diabetes, and myocardial infarctions.30), 31), 32) In a line with many studies, previous studies suggested that patients with high CHA2DS2-VASc score were associated with increased risk of post stroke AF, even in population without known history of AF.29) Therefore, in our study we used CHA2DS2-VASc score to estimate clinical risks for prevalence of post stroke AF. Interestingly, our results demonstrated better predictive performance of global LALS than that of CHA2DS2-VASc score. Previous study by Schnabel et al.33) suggested that echocardiographic parameters did not improve the risk function for predicting AF in Framingham population, however, their studies relied on M-mode echocardiographic parameters. 2D speckle tracking is an advanced new technique which allows a more direct measurement of LA contractility of endocardium and passive deformation, which well reflects function of LA.13) Structural remodeling of LA from fibrosis is important in pathogenesis of AF, and previous studies showed that the LALS well correlated with fibrosis of LA.16) Usefulness of the LALS is evidenced by several previous studies demonstrating that LA strain well predicts not only AF recurrence after radiofrequency ablation, but also reverse remodeling of LA.4), 34), 35), 36) Overall, our results suggest that global LALS provide additive predictive value to clinical risk predicting tool, CHA2DS2-VASc score for predicting post stroke AF in acute ischemic stroke patients.

Potential clinical applications

The mean value of global LALS of our cohort was 25 ± 8, which is lower when compared to earlier studies demonstrating feasibility of LALS in normal healthy population.37), 38) However, considering that age and associated cardiovascular diseases of our cohort, the mean value of global LALS should be lower as atrial function deteriorates with aging and underlying cardiovascular disease. When compared to previous studies regarding LALS in elderly population or in patients with acute stroke or systemic embolism, our result provided similar ranges of global LALS.21), 39)

As results from our study demonstrate that global LALS was significant predictor for post stroke AF, patients with lower LALS may benefit from active monitor AF after acute ischemic stroke. Global LALS could provide additive information to select patients who are most likely to benefit from prolonged monitoring of rhythm with implantable loop recorders. Furthermore, the global LALS may provide evidence for initiation of anticoagulation in absence of documented AF in acute ischemic stroke patients. Impairment of LA function reflected by decreased global LALS may attribute to flow stasis in LA, susceptible for thrombus formation. Although further studies are warranted for causal relationships between LA function and post stroke AF, it is possible that functional impairment from various cardiovascular conditions could trigger post stroke AF, which results in further deteriorated function of LA and subsequent thrombus formation. Our results provide evidence for further studies to investigate implication of global LALS for post stroke AF in acute ischemic patients without previous AF.

Study limitations

A few limitations should be addressed in this study. First, this study is a retrospective observational study from a single center, with a limited number of patients who underwent TEE. Second, we have possibly underestimated the true incidence of AF in this population as not every patient underwent rhythm monitoring after discharge. However, all patients who admitted to the stroke unit were under continuous ECG monitoring during hospitalization. Also after discharge, 163 patients underwent serial (more than 1 ECG) ECG and 50 patients had 24 hr Holter from outpatient clinics. Third, as we exclude patients with severe valve diseases to demonstrate association between mechanical function of LA and post stroke AF. This is reflected by relatively low CHA2DS2-VASc of patients in our study. Although this cohort may not represent general population of stroke patients, our data suggest possible application of the global LALS in real world practice.

Conclusion

The global LALS assessed by 2D speckle tracking imaging provides incremental information for predicting post stroke AF over clinical variables, stroke severity, and LA volume index. The global LALS may reflect structural and functional susceptibility for AF, and provide new strategies to better risk stratification for post stroke AF in patients with acute ischemic stroke.

Acknowledgements

This study was supported by a research fund from Korean Society of Echocardiography (2012-31-0060).

References

    1. Hannon N, Sheehan O, Kelly L, Marnane M, Merwick A, Moore A, Kyne L, Duggan J, Moroney J, McCormack PM, Daly L, Fitz-Simon N, Harris D, Horgan G, Williams EB, Furie KL, Kelly PJ. Stroke associated with atrial fibrillation--incidence and early outcomes in the north Dublin population stroke study. Cerebrovasc Dis 2010;29:43–49.
    1. Vingerhoets F, Bogousslavsky J, Regli F, Van Melle G. Atrial fibrillation after acute stroke. Stroke 1993;24:26–30.
    1. Sposato LA, Klein FR, Jáuregui A, Ferrúa M, Klin P, Zamora R, Riccio PM, Rabinstein A. Newly diagnosed atrial fibrillation after acute ischemic stroke and transient ischemic attack: importance of immediate and prolonged continuous cardiac monitoring. J Stroke Cerebrovasc Dis 2012;21:210–216.
    1. Schneider C, Malisius R, Krause K, Lampe F, Bahlmann E, Boczor S, Antz M, Ernst S, Kuck KH. Strain rate imaging for functional quantification of the left atrium: atrial deformation predicts the maintenance of sinus rhythm after catheter ablation of atrial fibrillation. Eur Heart J 2008;29:1397–1409.
    1. Sposato LA, Riccio PM, Hachinski V. Poststroke atrial fibrillation: cause or consequence? Critical review of current views. Neurology 2014;82:1180–1186.
    1. Kuppahally SS, Akoum N, Burgon NS, Badger TJ, Kholmovski EG, Vijayakumar S, Rao SN, Blauer J, Fish EN, Dibella EV, Macleod RS, McGann C, Litwin SE, Marrouche NF. Left atrial strain and strain rate in patients with paroxysmal and persistent atrial fibrillation: relationship to left atrial structural remodeling detected by delayed-enhancement MRI. Circ Cardiovasc Imaging 2010;3:231–239.
    1. Benito B, Gay-Jordi G, Serrano-Mollar A, Guasch E, Shi Y, Tardif JC, Brugada J, Nattel S, Mont L. Cardiac arrhythmogenic remodeling in a rat model of long-term intensive exercise training. Circulation 2011;123:13–22.
    1. Mattle HP. Long-term outcome after stroke due to atrial fibrillation. Cerebrovasc Dis 2003;16 Suppl 1:3–8.
    1. Francis DA, Heron JR, Clarke M. Ambulatory electrocardiographic monitoring in patients with transient focal cerebral ischaemia. J Neurol Neurosurg Psychiatry 1984;47:256–259.
    1. Kessler DK, Kessler KM. Is ambulatory electrocardiography useful in the evaluation of patients with recent stroke? Chest 1995;107:916–918.
    1. Jabaudon D, Sztajzel J, Sievert K, Landis T, Sztajzel R. Usefulness of ambulatory 7-day ECG monitoring for the detection of atrial fibrillation and flutter after acute stroke and transient ischemic attack. Stroke 2004;35:1647–1651.
    1. Sposato LA, Cipriano LE, Saposnik G, Ruíz Vargas E, Riccio PM, Hachinski V. Diagnosis of atrial fibrillation after stroke and transient ischaemic attack: a systematic review and meta-analysis. Lancet Neurol 2015;14:377–387.
    1. Vianna-Pinton R, Moreno CA, Baxter CM, Lee KS, Tsang TS, Appleton CP. Two-dimensional speckle-tracking echocardiography of the left atrium: feasibility and regional contraction and relaxation differences in normal subjects. J Am Soc Echocardiogr 2009;22:299–305.
    1. Sarvari SI, Haugaa KH, Stokke TM, Ansari HZ, Leren IS, Hegbom F, Smiseth OA, Edvardsen T. Strain echocardiographic assessment of left atrial function predicts recurrence of atrial fibrillation. Eur Heart J Cardiovasc Imaging. 2015 Jul 27; [doi: 10.1093/ehjci/jev185]
      [Epub].
    1. Cameli M, Lisi M, Righini FM, Massoni A, Natali BM, Focardi M, Tacchini D, Geyer A, Curci V, Di Tommaso C, Lisi G, Maccherini M, Chiavarelli M, Massetti M, Tanganelli P, Mondillo S. Usefulness of atrial deformation analysis to predict left atrial fibrosis and endocardial thickness in patients undergoing mitral valve operations for severe mitral regurgitation secondary to mitral valve prolapse. Am J Cardiol 2013;111:595–601.
    1. Habibi M, Lima JA, Khurram IM, Zimmerman SL, Zipunnikov V, Fukumoto K, Spragg D, Ashikaga H, Rickard H, Marine JE, Calkins H, Nazarian S. Association of left atrial function and left atrial enhancement in patients with atrial fibrillation: cardiac magnetic resonance study. Circ Cardiovasc Imaging 2015;8:e002769.
    1. Shaikh AY, Maan A, Khan UA, Aurigemma GP, Hill JC, Kane JL, Tighe DA, Mick E, McManus DD. Speckle echocardiographic left atrial strain and stiffness index as predictors of maintenance of sinus rhythm after cardioversion for atrial fibrillation: a prospective study. Cardiovasc Ultrasound 2012;10:48.
    1. Adams HP Jr, Bendixen BH, Kappelle LJ, Biller J, Love BB, Gordon DL, Marsh EE 3rd. Classification of subtype of acute ischemic stroke. Definitions for use in a multicenter clinical trial. TOAST. Trial of Org 10172 in Acute Stroke Treatment. Stroke 1993;24:35–41.
    1. Lip GY, Nieuwlaat R, Pisters R, Lane DA, Crijns HJ. Refining clinical risk stratification for predicting stroke and thromboembolism in atrial fibrillation using a novel risk factor-based approach: the euro heart survey on atrial fibrillation. Chest 2010;137:263–272.
    1. Lang RM, Bierig M, Devereux RB, Flachskampf FA, Foster E, Pellikka PA, Picard MH, Roman MJ, Seward J, Shanewise JS, Solomon SD, Spencer KT, Sutton MS, Stewart WJ. Chamber Quantification Writing Group; American Society of Echocardiography's Guidelines and Standards Committee; European Association of Echocardiography. Recommendations for chamber quantification: a report from the American Society of Echocardiography's Guidelines and Standards Committee and the Chamber Quantification Writing Group, developed in conjunction with the European Association of Echocardiography, a branch of the European Society of Cardiology. J Am Soc Echocardiogr 2005;18:1440–1463.
    1. Obokata M, Negishi K, Kurosawa K, Tateno R, Tange S, Arai M, Amano M, Kurabayashi M. Left atrial strain provides incremental value for embolism risk stratification over CHA2DS2-VASc score and indicates prognostic impact in patients with atrial fibrillation. J Am Soc Echocardiogr 2014;27:709–716.e4..
    1. Shih JY, Tsai WC, Huang YY, Liu YW, Lin CC, Huang YS, Tsai LM, Lin LJ. Association of decreased left atrial strain and strain rate with stroke in chronic atrial fibrillation. J Am Soc Echocardiogr 2011;24:513–519.
    1. Stroke Prevention in Atrial Fibrillation Investigators Committee on Echocardiography. Transesophageal echocardiography in atrial fibrillation: standards for acquisition and interpretation and assessment of interobserver variability. J Am Soc Echocardiogr 1996;9:556–566.
    1. Manning WJ, Weintraub RM, Waksmonski CA, Haering JM, Rooney PS, Maslow AD, Johnson RG, Douglas PS. Accuracy of transesophageal echocardiography for identifying left atrial thrombi. A prospective, intraoperative study. Ann Intern Med 1995;123:817–822.
    1. Beppu S, Nimura Y, Sakakibara H, Nagata S, Park YD, Izumi S. Smoke-like echo in the left atrial cavity in mitral valve disease: its features and significance. J Am Coll Cardiol 1985;6:744–749.
    1. Vincelj J, Sokol I, Jaksić O. Prevalence and clinical significance of left atrial spontaneous echo contrast detected by transesophageal echocardiography. Echocardiography 2002;19:319–324.
    1. DeLong ER, DeLong DM, Clarke-Pearson DL. Comparing the areas under two or more correlated receiver operating characteristic curves: a nonparametric approach. Biometrics 1988;44:837–845.
    1. Secondary prevention in non-rheumatic atrial fibrillation after transient ischaemic attack or minor stroke. EAFT (European Atrial Fibrillation Trial) Study Group. Lancet 1993;342:1255–1262.
    1. Fauchier L, Clementy N, Pelade C, Collignon C, Nicolle E, Lip GY. Patients wth ischemic stroke and incident atrial fibrillation: a nationwide cohort study. Stroke 2015;46:2432–2437.
    1. Benjamin EJ, Levy D, Vaziri SM, D'Agostino RB, Belanger AJ, Wolf PA. Independent risk factors for atrial fibrillation in a population-based cohort. The Framingham Heart Study. JAMA 1994;271:840–844.
    1. Psaty BM, Manolio TA, Kuller LH, Kronmal RA, Cushman M, Fried LP, White R, Furberg CD, Rautaharju PM. Incidence of and risk factors for atrial fibrillation in older adults. Circulation 1997;96:2455–2461.
    1. Huxley RR, Filion KB, Konety S, Alonso A. Meta-analysis of cohort and case-control studies of type 2 diabetes mellitus and risk of atrial fibrillation. Am J Cardiol 2011;108:56–62.
    1. Schnabel RB, Sullivan LM, Levy D, Pencina MJ, Massaro JM, D'Agostino RB Sr, Newton-Cheh C, Yamamoto JF, Magnani JW, Tadros TM, Kannel WB, Wang TJ, Ellinor PT, Wolf PA, Vasan RS, Benjamin EJ. Development of a risk score for atrial fibrillation (Framingham Heart Study): a community-based cohort study. Lancet 2009;373:739–745.
    1. Hammerstingl C, Schwekendiek M, Momcilovic D, Schueler R, Sinning JM, Schrickel JW, Mittmann-Braun E, Nickenig G, Lickfett L. Left atrial deformation imaging with ultrasound based two-dimensional speckle-tracking predicts the rate of recurrence of paroxysmal and persistent atrial fibrillation after successful ablation procedures. J Cardiovasc Electrophysiol 2012;23:247–255.
    1. Yasuda R, Murata M, Roberts R, Tokuda H, Minakata Y, Suzuki K, Tsuruta H, Kimura T, Nishiyama N, Fukumoto K, Aizawa Y, Tanimoto K, Takatsuki S, Abe T, Fukuda K. Left atrial strain is a powerful predictor of atrial fibrillation recurrence after catheter ablation: study of a heterogeneous population with sinus rhythm or atrial fibrillation. Eur Heart J Cardiovasc Imaging 2015;16:1008–1014.
    1. Tops LF, Delgado V, Bertini M, Marsan NA, Den Uijl DW, Trines SA, Zeppenfeld K, Holman E, Schalij MJ, Bax JJ. Left atrial strain predicts reverse remodeling after catheter ablation for atrial fibrillation. J Am Coll Cardiol 2011;57:324–331.
    1. Cameli M, Caputo M, Mondillo S, Ballo P, Palmerini E, Lisi M, Marino E, Galderisi M. Feasibility and reference values of left atrial longitudinal strain imaging by two-dimensional speckle tracking. Cardiovasc Ultrasound 2009;7:6.
    1. Kim DG, Lee KJ, Lee S, Jeong SY, Lee YS, Choi YJ, Yoon HS, Kim JH, Jeong KT, Park SC, Park M. Feasibility of two-dimensional global longitudinal strain and strain rate imaging for the assessment of left atrial function: a study in subjects with a low probability of cardiovascular disease and normal exercise capacity. Echocardiography 2009;26:1179–1187.
    1. Verdejo HE, Becerra E, Zalaquet R, Del Campo A, Garcia L, Troncoso R, Chiong M, Marin A, Castro PF, Lavandero S, Gabrielli L, Corbalán R. Atrial function assessed by speckle tracking echocardiography is a good predictor of postoperative atrial fibrillation in elderly patients. Echocardiography 2016;33:242–248.

Metrics
Share
Figures

1 / 2

Tables

1 / 3

Funding Information
PERMALINK