Increased Left Atrial Size Research Articles

Left atrial volume assessed by echocardiography identifies patients with high risk of adverse outcome after acute myocardial infarction

BackgroundThe left atrial (LA) volume has been demonstrated to be an important predictor of adverse outcome in patients with various cardiac conditions, including acute myocardial infarction (AMI). However, new treatment strategies in patients with AMI have led to better patient outcomes. We hypothesised that increased LA size could still predict mortality in patients with AMI despite improved treatment strategies.MethodsWe included patients with AMI in a prospective multicenter cohort study and the study patients were enrolled from 2014 to 2022. We recorded echocardiographic and clinical data during their index hospitalisation. Indexed LA volume (LAVi) was assessed in all patients and was used as a continuous variable in the univariate and multivariate Cox regression analysis. The study took place over a period of five years and median follow-up time was 3.8 years (range 3.1 to 5.0 years). The primary study outcomes were all-cause mortality and major adverse cardiac events (MACE). MACE was defined as hospital readmission due to myocardial infarction, cardiac arrest, stroke, heart failure, or onset of new atrial fibrillation.ResultsWe included 487 patients (69 ± 12 years old, 26% female) with AMI. During the follow-up period all-cause mortality was 50 (10.3%) and patients who reached the primary outcomes were 153 (31.4%). The deceased patients had higher LAVi compared to survivors (40.0 ± 12.9 mL/m2 vs. 29.7 ± 11.2 mL/m2, p < 0.001). Factors associated with all-cause mortality and MACE were age, year of enrollment, left ventricular (LV) ejection fraction, LV global longitudinal strain (GLS), LV filling pressure, moderate or severe mitral regurgitation and LAVi. GLS and EF were segregated into two distinct models due to their moderately high correlation (r = 0.57, p < 0.001). LAVi remained as an independent echocardiographic predictor of primary outcomes after adjusting for the covariates above in two separates multivariable Cox regression models (hazard ratio 1.02/1.02 mL/m2 [95% CI 1.01–1.03/1.01–1.03], p = 0.006/0.003).ConclusionsOur study demonstrated that LA dilatation is an independent echocardiographic predictor of mortality and MACE in patients with AMI despite improved treatment strategies. This finding highlights the potential of using LAVi as a marker for prognostication in these patients.

Characterizing the influence of cardiorespiratory fitness on left atrial size and function in the general population.

Increased left atrial (LA) size and reduced LA function have been associated with heart failure and atrial fibrillation (AF) in at-risk populations. However, atrial remodeling has also been associated with exercise training and the relationship between fitness, LA size, and function has not been defined across the fitness spectrum. In a cross-sectional study of 559 ostensibly healthy participants, comprising 304 males (mean age, 46 ± 20 yr) and 255 females (mean age, 47 ± 15 yr), we sought to define the relationship between cardiorespiratory fitness (CRF), LA size, and function. We also aimed to interrogate sex differences in atrial factors influencing CRF. Echocardiographic measures included biplane measures of LA volumes indexed to body surface area (LAVi) and atrial deformation using two-dimensional speckle tracking. CRF was measured as peak oxygen consumption (V̇o2peak) during cardiopulmonary exercise testing (CPET). Using multivariable regression, age, sex, weight, and LAVi (P < 0.001 for all) predicted V̇o2peak (P < 0.001, R2 = 0.66 for combined model). After accounting for these variables, heart rate reserve added strength to the model (P < 0.001, R2 = 0.74) but LA strain parameters did not predict V̇o2peak. These findings add important nuance to the perception that LA size is a marker of cardiac pathology. LA size should be considered in the context of fitness, and it is likely that the adverse prognostic associations of increased LA size may be confined to those with LA enlargement and low fitness.NEW & NOTEWORTHY Left atrial (LA) structure better predicts cardiorespiratory fitness (CRF) than LA function. LA function adds little statistical value to predictive models of peak oxygen uptake (V̇o2peak) in healthy individuals, suggesting limited discriminatory for CRF once LA size is factored. In the wider population of ostensibly healthy individuals, the association between increased LA volume and higher CRF provides an important counter to the association between atrial enlargement and heart failure symptoms in those with cardiac pathology.

Abstract 16161: Effects of Year Long Aerobic Exercise on Left Atrial Size in Patients With Left Ventricular Hypertrophy

Introduction: Habitual aerobic exercise is associated with left atrial (LA) enlargement and risk of atrial fibrillation. This risk may be accentuated in patients with increased left ventricular (LV) stiffness due to high LA pressure during exercise. We tested the hypothesis that 1 year long endurance exercise would increase LA size to a greater extent in patients with left ventricular hypertrophy (LVH) at risk for heart failure with preserved ejection fraction (HFpEF) than previously published age appropriate controls. Methods: Middle-aged adults (age 45-64 yrs) with LVH (n=53) enriched for increased HFpEF risk (N-terminal pro-B-type natriuretic peptide &gt;40 pg/mL or high-sensitivity cardiac troponin T &gt;0.6 pg/mL) and healthy subjects (n=58) were randomized to one year of high intensity aerobic exercise or yoga control. LA and LV volumes were measured using 3D echo. Results: Of 111 participants, 83 had complete data available (LVH cohort: 18 exercisers, 10 yoga; healthy cohort: 29 exercisers, 26 yoga). Baseline LA size was larger in LVH vs healthy subjects (42 ± 12 vs 35 ± 9 mL; p=0.005). There was a nominal increase in LA size in LVH exercisers compared to LVH yoga (8 ± 9 vs 4 ± 7 mL; p=0.29) which was proportional to LV size (LA/LV ratio 0.05 ± 0.07 vs 0.06 ± 0.1; p=0.81). Healthy subject exercisers increased LA size compared to healthy yoga controls (4 ± 5 vs 0 ± 6 mL; p=0.02) with no increase in LA/LV ratio (-0.02 ± 0.08 vs -0.03 ± 0.08; p=0.62). Among exercising subjects only, increase in LA size was larger in LVH compared to healthy subjects after year long aerobic training (p=0.04) with greater increase LA/LV ratio (p&lt;0.001). Conclusions: One year of aerobic training resulted in higher LA size in patients with at-risk LVH compared to healthy subjects. The increase in LA size was greater than changes in LV size suggesting chronic aerobic training may preferentially affect LA remodeling.

Left atrial dynamics and the pulmonary circulatory-right ventricular uncoupling in patients with severe degenerative mitral regurgitation

Abstract Funding Acknowledgements Type of funding sources: None. Background The uncoupling of right ventricular (RV) function to pulmonary circulation (Pc) represents a prognostic index in patients affected by degenerative mitral regurgitation (DMR) undergoing surgical or percutaneous repair. In this context, the deterioration of Left Atrial (LA) dynamics favors the development of pulmonary venous congestion and vascular remodeling, triggering pulmonary hypertension (PH) and right ventricular (RV) dysfunction. However, the relationship between LA function and RV-to-Pc coupling is not well defined in this population. Purpose The aim of the study was to investigate the association between RV-to-Pc uncoupling, assessed by the ratio between tricuspid annular plane systolic excursion (TAPSE) and pulmonary artery systolic pressure (PAPS), and LA dynamics, evaluated with Speckle Tracking Echocardiography (STE), in patients with DMR. Methods 351 consecutive patients with hemodynamically-significant DMR who were evaluated for cardiac surgery at San Raffaele Hospital and underwent a complete transthoracic and transesophageal echocardiography were retrospectively enrolled (mean age 59±14 years, 65% males). Patients were then stratified in two groups according to TAPSE/PAPS ratio (group I: TAPSE/PAPS &amp;gt;0.4 mm/mmHg; group II: TAPSE/PAPS ≤0.4 mm/mmHg). LA function was evaluated analyzing LA strain at peak relaxation (Global peak atrial longitudinal strain) and STE analysis was performed offline. All the patients enrolled were in sinus rhythm. Results At baseline, patients exhibited normal LV dimensions and function (EDVi 70±20 ml/m2, LVEF 63±6%), increased LA size (48±20 ml/m2) and a mean GPALS of 26±13%. Additionally, a preserved RV function and coupling with PC was found in the population in study (average TAPSE/PASP at admission: 0.84±0.2 mm/mmHg), with only 10% of the cohort exhibiting a reduced TAPSE/PAPS ratio. When stratified according to RV-to-PC coupling, patients with higher TAPSE/PAPS (&amp;gt;0.4 mm/mmHg) exhibited significantly higher values of LA reservoir strain (group I: GPALS 27.8±12.7% vs group II GPALS 22.7±11.3%; p = 0.04) (Figure 1, 2). Additionally, a direct correlation between LA-Strain values and TAPSE/PAPS ratio was noticed (r=0.3, CI 95% 0.21–0.5; p&amp;lt;0.001). Conclusions In DMR, there is a strong association between echo-derived measures of LA mechanics and RV to Pc uncoupling, with higher values of LA strain correlating with a better RV functioning and coupling. These results, although preliminary, suggest the importance of a multiparametric approach in the risk-stratification of these patients, potentially improving the long-term outcome.

Abstract 11959: Left Atrial Size and Function in Children and Young Adults With Obstructive vs. Nonobstructive Hypertrophic Cardiomyopathy

Introduction: Left atrial (LA) strain has been recently used to improve assessment of left atrial (LA) function. In adults with hypertrophic cardiomyopathy (HCM), increased LA size and decreased LA strain are associated with LVOT obstruction (LVOTO) and higher risk for adverse cardiovascular outcomes. Scant data exists on the association of LA strain and size in children with HCM, comparing those with and without obstruction. Methods: For this pilot study, all patients from an existing pediatric BCH stress echo HCM registry who had adequate echocardiographic images to assess both LA size and strain were consecutively enrolled and retrospectively reviewed. Post-processing LA size and strain (reservoir and conduit) were performed with use of Tomtec/Philips LV strain. Children with HCM were divided into 2 groups: those with resting LVOT gradients &lt;30 mm Hg (no obstruction) versus ≥30 mm Hg (obstruction). LA size, strain and diastolic indices were compared for those with and without obstruction. Results: A total of 48 children (63% male, median age 13 yrs, range 6-23yrs) with HCM and analyzable images from the registry formed the cohort. Patient demographics, LA size and strain, and diastolic indices are summarized in Table 1. HCM children with LVOTO had larger LA size (apical 4-chamber (A4C) cross sectional area: p&lt;0.001), lower LA conduit and reservoir strain (p&lt;0.05 for all), and increased diastolic dysfunction (p&lt;0.05 for all). Conclusions: Despite their younger age, children with obstructive HCM had larger LA size, lower LA reservoir and conduit strain, and increased diastolic dysfunction compared to children with nonobstructive HCM. Larger studies are needed with longer follow-up time to assess association of LA strain with cardiac events in children.

Impaired Left Atrial Performance Resulting From Age-Related Arial Fibrillation Is Associated With Increased Fibrosis Burden: Insights From a Clinical Study Combining With an in vivo Experiment.

Background: Atrial fibrillation (AF) is increasingly considered an age-related degenerative disease, whose process is associated with the development of impaired left atrial (LA) performance. However, the subtle dynamic changes of LA performance in AF during aging have yet to be fully elucidated. Atrial fibrosis is a key substrate for the development of AF, but the progression of fibrosis during aging and its relationship with LA dysfunction need to be further explored.Methods: A total of 132 control individuals and 117 persistent AF patients were prospectively studied. Subjects were further stratified into three age groups (age group 1: younger than 65 years, age group 2: between 65 and 79 years old, and age group 3: older than 80 years). The two-dimensional speckle tracking imaging was carried out for analyzing the alterations in LA function underlying LA remodeling, whereas electroanatomic mapping was performed to investigate LA fibrosis burden. In animal study, aged mice and young mice served as research subjects. Echocardiography and histological staining were used to assess LA performance and fibrosis burden, respectively.Results: Echocardiography showed progressive increases in LA dimension and LA stiffness index, and progressive decreases in LA global longitudinal strain and LA strain rates with advancing age in both AF and control cohorts, which was more prominent in AF cohort. Electroanatomic mapping showed progressive decrease in mean LA voltage and progressive increases in LA surface area, low-voltage area %, and LA volume with advancing age, whereas more significant alterations were observed in AF patients. Moreover, left atrial global longitudinal strain was positively correlated with mean LA voltage, whereas LA stiffness index was negatively related to mean LA voltage. In animal experiment, increased LA size and pulmonary artery dimension as well as longer P-wave duration and more prominent LA fibrosis were found in aged mice.Conclusions: This study provides new evidence of subtle changes in structure and performance of left atrium and their association with atrial fibrosis in both AF and non-AF subjects during physiological aging. In addition, our study also provides normal values for LA structure and performance in both AF and non-AF conditions during aging. These measurements may provide an early marker for onset of AF and LA adverse remodeling.

Malignant Left Atrial Appendage Morphology: Current Classification vs H-L System

IntroductionIn previous studies the risk of stroke recurrence has been associated with the left atrial appendage (LAA) morphology (non-chicken wing (NCW)), knowing those with a greater risk as malignant LAA. Recently, a simpler morphological classification has been suggested with two categories: Low-risk (LAA-L) and High-risk (LAA-H); which could be easier to apply and may correlate better with the risk of embolic stroke. MethodsRetrospective analysis from a registry of patients with recurrent cardioembolic strokes despite appropriate anticoagulant therapy, in which LAA morphology was studied with cardiac CT scan. LAA morphology was classified according to the four current categories and H-L morphology by the same cardiologist. Other variables associated with a high risk of stroke were also assessed, such as CHA2DS2-VASc score and left atrial (LA) size. ResultsTwenty-six cases were included in the analysis. We identified 22 (84.6%) chicken wing (CW), 1 (3.8%) windsock and 3 (11.5%) cactus by the current classification system, while 15 (57.7%) were classified as LAA-H and 11 (42.3%) as LAA-L by the new system. Half of the 22 cases with CW morphology were considered LAA-H, whereas all NCW were also classified as LAA-H. LA diameter and area were significantly higher in cases with LAA-H morphology (p=0.03 and 0.014), and also in those CW and LAA-H, compared to those CW with LAA-L (p=0.035). ConclusionsWith this new classification system more than half of the cases of our malignant LAAs were classified as high-risk morphology. This morphology was also associated with an increased LA size.

Left Atrial Size and Ischemic Events after Ischemic Stroke or Transient Ischemic Attack in Patients with Nonvalvular Atrial Fibrillation

Background: The present study aimed to clarify the association between left atrial (LA) size and ischemic events after ischemic stroke or transient ischemic attack (TIA) in patients with nonvalvular atrial fibrillation (NVAF). Methods: Acute ischemic stroke or TIA patients with NVAF were enrolled. LA size was classified into normal LA size, mild LA enlargement (LAE), moderate LAE, and severe LAE. The ischemic event was defined as ischemic stroke, TIA, carotid endarterectomy, carotid artery stenting, acute coronary syndrome or percutaneous coronary intervention, systemic embolism, aortic aneurysm rupture or dissection, peripheral artery disease requiring hospitalization, or venous thromboembolism. Results: A total of 1,043 patients (mean age, 78 years; 450 women) including 1,002 ischemic stroke and 41 TIA were analyzed. Of these, 351 patients (34%) had normal LA size, 298 (29%) had mild LAE, 198 (19%) had moderate LAE, and the remaining 196 (19%) had severe LAE. The median follow-up duration was 2.0 years (interquartile range, 0.9–2.1). During follow-up, 117 patients (11%) developed at least one ischemic event. The incidence rate of total ischemic events increased with increasing LA size. Severe LAE was independently associated with increased risk of ischemic events compared with normal LA size (multivariable-adjusted hazard ratio, 1.75; 95% confidence interval, 1.02–3.00). Conclusion: Severe LAE was associated with increased risk of ischemic events after ischemic stroke or TIA in patients with NVAF.

Differing mechanisms of atrial fibrillation in athletes and non-athletes: alterations in atrial structure and function.

Atrial fibrillation (AF) is more common in athletes and may be associated with adverse left atrial (LA) remodelling. We compared LA structure and function in athletes and non-athletes with and without AF. Individuals (144) were recruited from four groups (each n = 36): (i) endurance athletes with paroxysmal AF, (ii) endurance athletes without AF, (iii) non-athletes with paroxysmal AF, and (iv) non-athletic healthy controls. Detailed echocardiograms were performed. Athletes had 35% larger LA volumes and 51% larger left ventricular (LV) volumes vs. non-athletes. Non-athletes with AF had increased LA size compared with controls. LA/LV volume ratios were similar in both athlete groups and non-athlete controls, but LA volumes were differentially increased in non-athletes with AF. Diastolic function was impaired in non-athletes with AF vs. non-athletes without, while athletes with and without AF had normal diastolic function. Compared with non-AF athletes, athletes with AF had increased LA minimum volumes (22.6 ± 5.6 vs. 19.2 ± 6.7 mL/m2, P = 0.033), with reduced LA emptying fraction (0.49 ± 0.06 vs. 0.55 ± 0.12, P = 0.02), and LA expansion index (1.0 ± 0.3 vs. 1.2 ± 0.5, P = 0.03). LA reservoir and contractile strain were decreased in athletes and similar to non-athletes with AF. Functional associations differed between athletes and non-athletes with AF, suggesting different pathophysiological mechanisms. Diastolic dysfunction and reduced strain defined non-athletes with AF. Athletes had low atrial strain and those with AF had enlarged LA volumes and reduced atrial emptying, but preserved LV diastolic parameters. Thus, AF in athletes may be triggered by an atrial myopathy from exercise-induced haemodynamic stretch consequent to increased cardiac output.

P970 Significant differences in atrial structural and functional parameters leading to differing mechanisms of atrial fibrillation in athletes compared to non-athletes

Abstract Background/Introduction: There is an increased incidence of atrial fibrillation (AF) in endurance athletes. We sought to evaluate the likely mechanistic basis for this phenomenon. Methods 36 endurance athletes in sinus rhythm, with a previous history of AF (ATH-AF) were compared to age and gender matched endurance athletes with no prior history of AF (ATH), non athletes with paroxysmal AF (NONATH-AF) and age and gender matched healthy controls (CONTROL). A detailed transthoracic echocardiogram was performed with all groups in sinus rhythm, with detailed left atrial (LA) and left ventricular (LV) measurements, including strain analysis. Results All athletes had increased LA and LV size when compared with healthy controls (Table 1). Non athletes with paroxysmal AF had increased LA size when compared with controls. However, indexed LA/LV ratio was preserved in athletes and similar to healthy individuals, whilst AF patients had significantly increased LA/LV ratio. Athletes with AF had higher e’ velocity and lower E/e’, whereas e’ was reduced and E/e’ elevated in non-athlete AF patients. Athletes had impaired LA reservoir and contractile strain, and reduced LV global longitudinal strain (GLS) compared with healthy controls. Conclusions Compared to healthy controls, athletes have reduced LA and LV strain, with preserved LV diastolic function and LA/LV ratio. In contrast, altered diastolic function with differential increase in LA volume was observed in AF patients. The increased risk of AF in athletes is likely mediated by different mechanistic processes other than an atrial myopathy consequent to diastolic dysfunction as observed in non-athletes with AF. Table 1. LA and LV parameters Parameter ATH-AF ATH NONATH-AF CONTROL P value LVEDV indexed (ml/m2) 84 ± 12 79 ± 14 57 ± 10 51 ± 13 &amp;lt;0.001 LVESV indexed (ml/m2) 35 ± 6 34 ± 7 25 ± 8 27 ± 33 0.02 LV ejection fraction (%) 58 ± 4 56 ± 4 56 ± 10 58 ± 8 0.586 LV global longitudinal strain (%) 19.2 ± 1.7 18.9 ± 2.1 21 ± 3.1 21.7 ± 2.9 &amp;lt;0.001 e’ vel (cm/s) 10 ± 2 10 ± 3 8 ± 2 9 ± 2 0.007 E/e’ 5.7 ± 1.3 5.9 ± 1.8 9.1 ± 3.3 7.5 ± 1.5 &amp;lt;0.001 LAV max indexed (ml/m2) 45 ± 11 43 ± 12 38 ± 11 27 ± 8 &amp;lt;0.001 Indexed LAV/LVEDV ratio 0.5 ± 0.1 0.6 ± 0.2 0.7 ± 0.2 0.5 ± 0.1 &amp;lt;0.001 LA reservoir strain (%) 27.2 ± 4.8 28.2 ± 3.7 27.9 ± 8.4 33.2 ± 7.0 &amp;lt;0.001 LA conduit strain (%) 14.2 ± 4.5 14.4 ± 4.0 14.9 ± 5.5 16.6 ± 6.3 0.182 LA contractile strain (%) 13.0 ± 3.1 13.8 ± 3.6 13.0 ± 5.1 16.6 ± 3.1 &amp;lt;0.001 LV = left ventricular, LAV = left atrial volume, LA = left atrial

Two-dimensional echocardiographic estimates of left atrial function in healthy dogs and dogs with myxomatous mitral valve disease

ObjectivesTo provide reference intervals for 2-dimensional linear and area-based estimates of left atrial (LA) function in healthy dogs and to evaluate the ability of estimates of LA function to differentiate dogs with subclinical myxomatous mitral valve disease (MMVD) and similarly affected dogs with congestive heart failure (CHF). AnimalsFifty-two healthy adult dogs, 88 dogs with MMVD of varying severity. MethodsLinear and area measurements from 2-dimensional echocardiographs in both right parasternal long and short axis views optimized for the left atrium were used to derive estimates of LA active emptying fraction, passive emptying fraction, expansion index, and total fractional emptying. Differences for each estimate were compared between healthy and MMVD dogs (based on ACVIM classification), and between MMVD dogs with subclinical disease and CHF that had similar LA dimensions. Diagnostic utility at identifying CHF was examined for dogs with subclinical MMVD and CHF. Relationships with bodyweight were assessed. ResultsAll estimates of LA function decreased with increasing ACVIM stage of mitral valve disease (p<0.05) and showed negative relationships with increasing LA size (all r2 values < 0.2), except for LA passive emptying fraction, which did not differ or correlate with LA size (p=0.4). However, no index of LA function identified CHF better than measurements of LA size. Total LA fractional emptying and expansion index showed modest negative correlations with bodyweight. ConclusionsEstimates of LA function worsen with worsening MMVD but fail to discriminate dogs with CHF from those with subclinical MMVD any better than simple estimates of LA size.

Association of left atrial enlargement with ventricular remodeling in hypertensive Chinese elderly.

It is not well known whether left atrial (LA) enlargement is associated with left ventricular (LV) remodeling in Asian subjects with preserved LV ejection fraction (LVEF ≥50%). Therefore, we studied whether LA enlargement is related to ventricular remodeling in hypertensive Chinese elderly with preserved LVEF. Data of 480 hypertensive Chinese elderly (age from 65 to 94years) with LVEF ≥50% were consecutively included in the study. We observed a total of 248 patients (51.7%) with increased LA size. Univariate analysis showed that LA size was positively related to duration of hypertension, prevalence of coronary heart disease and atrial fibrillation, interventricular septal thickness, LV posterior wall thickness, LV end-diastolic and end-systolic diameter, LV mass index, right ventricular (RV) diameter and aortic diameter; meanwhile, LA size was inversely related to LVEF and relative wall thickness of LV. Multivariate regression analysis showed that LA enlargement was positively related to duration of hypertension (P=.012) and RV diameter (P<.001). Left atrial enlargement is independently associated with a longer duration of hypertension and RV dilative remodeling in hypertensive elderly with preserved LVEF. LA enlargement is an early sign of RV eccentric remodeling in hypertensive elderly.

Abstract 13677: Left Atrial Structure and Function in Relation to Incident Stroke/TIA and Dementia: The Multi-ethnic Study of Atherosclerosis

Introduction: Increased left atrial (LA) size and reduced LA function are known predictors of atrial fibrillation (AF). Evidence also links increased LA size and stroke. We sought to examine the association of LA function, measured with cardiac magnetic resonance imaging (CMR) and incident stroke/TIA and dementia. Methods: This case-cohort study compared LA size and function in 180 MESA participants with incident Stroke/TIA and 95 with incident dementia, over a median follow up of 10.7 years, to 550 participants randomly selected from the whole MESA cohort. All individuals were free of clinical cardiovascular and major valvular heart disease. Phasic LA volumes, LA emptying fractions (LAEF) and peak strain were quantified in sinus rhythm using tissue-tracking CMR. Vascular neurologists adjudicated stroke events by medical record review. Dementia cases were identified using ICD9 codes from hospital records. Modified Cox proportional hazard models weighted for the stratified case-cohort sampling design was used to examine the associations. Results: Incident Stroke/TIA (age 67 ± 9 years, 45% male) and dementia cases (age 74 ± 6 years, 58% male) were older than the subcohort population (age: 61 ± 10, 49% male). In multivariable analysis adjusted for standard cardiovascular risk factors and left ventricular ejection fraction, lower peak LA strain and passive LAEF were associated with both incident stroke/TIA and dementia. After further adjustment for incident AF, the associations were attenuated for peak LA strain but remained significant for passive LAEF (HR for incident Stroke/TIA: 0.72 per SD 95% CI: 0.55-0.93, p=0.013 and for incident dementia: 0.59 per SD 95% CI: 0.37-0.95, p=0.031). Conclusions: Reduced LA conduit function was associated with incident Stroke/TIA and dementia independent of other cardiovascular risk factors and incident AF. Assessment of LA function may add further information in risk stratifying individuals at risk for stroke and dementia.

PP.08.16

Objective: Hypertension(HTN) has severe consequences to the heart, leading to morphological and functional remodeling of left atrium. We sought to assess left atrial(LA) mechanical function in a group of hypertensives, matching it with healthy controls. Design and method: We prospectively enrolled 35 consecutive hypertensive patients (mild, moderate and severe HTN but pharmacological treated subjects). The secondary causes of hypertension, as well as significant valvular disease, thyroid dysfunctions, diabetes mellitus or any other important organ abnormality were excluded. LA diameters(antero-posterior, tranverse and longitudinal) LA volumes were measured by echocardiography, using the modified biplane Simpson method: maximal LA(LAV max), preatrial contraction LA(LAV preA) and minimal LA volume(LAV min). LA emptying functions were calculated: LA total EF(LAV max-LAVmin)/LAV max, LA passive EF = (LAVmax-LAVpreA)/LAVmax and LA active EF(LAVpreA-LAVmin)/LAVpreA. Peak longitudinal strain of LA walls were analysed using 2D speckle-tracking echocardiography. The results were compared with a group of 37 age-matched healthy controls. Results: In the HTN group the mean time of arterial hypertension diagnosis was 33 months and the mean blood pressure(24 hour ambulatory blood pressure monitoring) was 139/74mmHg. LA antero-posterior diameter and all the volumes(LAVmax, LAVmin and LAVpreA) were significantly greater in hypertensives compared to controls(p < 0.0001), while the transversal and longitudinal diameters were similar. LA active EF was similar between the two groups, but we found significantly lower LA passive and total EF in hypertensives than in the control group(p < 0.0001). The peak strain values were also significantly lower in HTN group compared to control(22.7 versus 35.1, p < 0.0001). Conclusions: In our study, arterial hypertension was associated with increased LA size (anteroposterior diameter and volumes), a decrease in LA passive EF and in LA total EF, with preserved atrial pump function. LA dysfunction was also demonstrated through low peak strain values.

168 Atrial arrhythmias and electrical remodelling after endurance training in a mouse model of arrhythmogenic right ventricular cardiomyopathy

<h3>Background and purpose</h3> Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited disorder that causes ventricular arrhythmias and sudden death. The disease manifests predominantly in the right heart and is more common in endurance athletes. ARVC patients also show increased atrial arrhythmias. Loss-of-function mutations in desmosomal proteins such as plakoglobin are associated with ARVC, and endurance training exacerbates ventricular arrhythmias and right ventricular enlargement in mice with reduced expression of plakoglobin (Plako^+/–). Chronic intensive endurance training has recently been observed to increase susceptibility to atrial arrhythmias in rats. We therefore tested whether standardised endurance training affects atrial electrophysiology or increases in mice with heterozygous plakoglobin deficiency (Plako^+/–). <h3>Methods</h3> Plako^+/– and WT mice group swim-trained for 5 d/week over 8 weeks, gradually increased from 2 to 90 min/d (average swim times 50h). Atrial size and function was assessed by echocardiography. Left atrial (LA) monophasic action potentials (MAPs) were recorded from Langendorff-perfused hearts. Action potential durations (APDs) were measured during RA pacing at 100ms paced cycle lengths (CL). Atrial arrhythmias were provoked by programmed stimulation (S1-S2). Atrial arrhythmias were defined as fast irregular atrial activity &gt;1s). Transmembrane action potentials (TAPs) were recorded at 100ms CL from isolated, superfused LA using floating glass microelectrodes. All continuous parameters are expressed as mean±SEM. <h3>Results</h3> Swim-training increased atrial arrhythmia susceptibility in Plako^+/–but not WT mice (Plako^+/– sedentary: 1/9 vs trained: 9/17 hearts),(WT sedentary: 3/11 hearts vs trained: 1/11 hearts). Training induced mild leftventricular hypertrophy in both genotypes (LV mass increase 6–14%, p &lt; 0.05). As shown previously, training also increased right ventricular size in Plako^+/– vs. trained WT, e.g. Parasternal RV diameter Plako^+/– (1.79 ± 0.03 mm) vs. WT (1.66 ± 0.02 mm) after training, p &lt; 0.05. Training increased LA size as assessed in echocardiography in both genotypes versus sedentary (LA size WT: 3.11 ± 0.14 sedentary vs 3.79 ± 0.17 mm² trained, p &lt; 0.05; Plako^+/–: 3.23 ± 0.1 mm² sedentary vs 4.14 ± 0.23 mm² trained, p &lt; 0.05). LA APD from MAPs tended to be shorter in trained WT and were significantly shorter in trained Plako^+/- mice (Figure 2). RA APD90s measured from TAPs were also shorter after training (WT: 22 ± 1 sedentary vs 19 ± 1 ms trained; Plako^+/- 24 ± 1 sedentary vs 18 ± 1 ms trained). <h3>Conclusion</h3> Our observations suggest that endurance training shortens atrial action potential duration and increases left atrial size in both WT and plakoglobin deficient atria. Endurance training increased atrial arrhythmia susceptibility in mice with a deficiency in the mechanical cell-cell contact protein plakoglobin.

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

BackgroundLeft 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.MethodsCross-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.ResultsExcept 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, CI95% 0.644- 0.772, p<0.001; LAA low flow velocities: AUC = 0.733, CI95% 0.674- 0.793, p<0.001; dense spontaneous echocardiographic contrast: AUC = 0.693, CI95% 0.638- 0.748, p<0.001; LA abnormality: AUC = 0.705, CI95% 0.654-0.755, p<0.001), indexed single-plane area-length volume (LAA thrombus: AUC = 0.701, CI95% 0.633-0.770, p<0.001; LAA low flow velocities: AUC = 0.726, CI95% 0.660-0.792, p<0.001; dense spontaneous echocardiographic contrast: AUC = 0.673, CI95% 0.611-0.736, p<0.001; LA abnormality: AUC = 0.687, CI95% 0.629-0.744, p<0.001), and indexed biplane area-length volume (LAA thrombus: AUC = 0.707, CI95% 0.626-0.788, p<0.001; LAA low flow velocities: AUC = 0.737, CI95% 0.664-0.810, p<0.001; dense spontaneous echocardiographic contrast: AUC = 0.651, CI95% 0.578-0.724, p<0.001; LA abnormality: AUC = 0.683, CI95% 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.ConclusionsLeft 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.

Changes in left atrial functional indexes in ischemic stroke patients

BackgroundIncreased left atrial (LA) size has been proposed as a predictor of multiple adverse cardiovascular events including stroke. LA dysfunction can occur in the absence of increased LA size. However, the relationship between stroke and changes in LA function is not well known. MethodsPatients with acute ischemic stroke and healthy controls were enrolled prospectively. Stroke patients received standard work-ups to determine the etiology of their strokes. Those patients with significant cardiac arrhythmia and heart failure were excluded. All participants received echocardiography examination. Conventional echocardiographic parameters were calculated and cardiac contractile characteristics of the left atrium and left ventricle were analyzed using vector velocity imaging (VVI) technique. ResultsIn total, 87 patients with acute ischemic stroke and 20 controls were recruited. The mitral inflow E-wave velocities were lower and A-wave velocities were higher in stroke patients (0.76 ± 0.19 vs. 0.84 ± 0.16, p = 0.048; and 0.97 ± 0.20 vs. 0.76 ± 0.11, p < 0.001 respectively). Stroke patients had a higher active emptying percent of total LA emptying (60.5 ± 19.0%) compared with that in controls (33.5 ± 11.7%, p < 0.001). The minimal LA volume was larger in stroke patients (15.0 ± 10.5 mL) than that in controls (9.9 ± 4.2 mL, p = 0.021), whereas there was no difference in maximal LA volume between stroke patients (37.3 ± 16.5 mL) and controls (33.3 ± 9.9 ml, p = 0.366). The diastolic emptying index of the LA was significantly lower in stroke patients compared with that in controls (61.4 ± 14.6% vs. 70.2 ± 11.0%, p = 0.016). The mitral A-wave velocity and active emptying percent of total LA emptying were significantly higher in all stroke subtypes than those in controls. ConclusionAcute ischemic stroke patients had altered mitral inflow velocities and emptying function of the left atrium. VVI is convenient for quantitative assessment of left atrial volumes and contractile characteristics. Functional changes of LA may occur without significant structural changes. Therefore, the clinical implications of LA functional indexes require further study.

ATRIAL FIBRILLATION POST CARDIAC SURGERY: INCIDENCE, PREDISPOSING FACTORS AND PROGNOSTIC IMPLICATIONS.

postcardiac surgery and is associated with significant morbidity, increased overall hospital stay and cost. Anecdotal observations suggest very low incidence in Pakistani patients undergoing cardiac surgery particularly coronary artery bypass graft surgery (CABG). The objective of this study was to assess the prevalence, morbidity & mortality of post cardiac surgery AF. METHODS: A prospective study of 201 consecutive patients undergoing cardiac surgery at a tertiary care center. Clinical characteristics and perioperative data was collected & analyzed. Patients were followed for presence or absence of atrial fibrillation till hospital discharge. RESULTS: The overall incidence of AF post cardiac surgery was 6.9 %. AF occurred in 9 of 187 patients undergoing CABG alone, 3 of 12 patients undergoing valve replacement and 2 of 2 undergoing combined procedures. Increased left atrial (LA) size had significant association with post cardiac surgery AF (p = 0.01) as did the use of dopamine and epinephrine post operatively (p = 0.03 & 0.002 respectively). In addition, significant association was also noted for valvular surgery (p = <0.001). Multiple logistic regression analysis revealed that increased LA size (odds ratio 0.08, 95% CI 0.008-0.99, p = 0.04) was the only independent predictor of post cardiac surgery AF with borderline significance for concomitant valvular surgery (odds ratio 0.89, 95% CI 0.79-0.99, p = 0.05). Mean hospital stay was significantly longer & overall cost was significantly higher in patients who developed AF (p = <0.001) in addition to higher overall mortality (p =0.025). CONCLUSIONS: The incidence of AF post cardiac surgery was quite low in this study cohort. The occurrence of atrial fibrillation, albeit for short duration, was associated with higher all cause mortality, significantly longer hospital stay and higher overall cost.

Left atrial myxoma—influence of tumour size on electrocardiographic findings

ObjectiveThe data of 51 patients (33 females) who underwent excision of left atrial (LA) myxoma were retrospectively reviewed for correlation of tumour size and electrocardiographic (ECG) findings. Methods and resultsMean age was 39.1 ± 15 years (range 9–53 years). The LA enlargement (LAE) on ECG was defined by standard criteria. The LAE in ECG in these patients did not correlate with echocardiographic LA dimensions or with the degree of left ventricular (LV) inflow obstruction. But it was found that the presence of LAE in ECG predicted maximum tumour dimension of >5 cm and correlated with the degree of mitral regurgitation (MR). The LAE in ECG disappeared following surgery in 87.5% of patients. ConclusionThe LA enlargement on ECG in a patient with LA myxoma signifies larger tumour size or the presence of significant MR but is not necessarily associated with an increased LA size or LV inflow obstruction.

Risk for atrial fibrillation in patients with hypertrophic cardiomyopathy: Association with insulin resistance

We undertook a cross-sectional study to test the hypothesis that patients with hypertrophic cardiomyopathy (HCM) who have impaired left ventricular (LV) diastolic function are insulin resistant. We also evaluated the relation between the development of atrial fibrillation (AF) and insulin resistance (IR) in patients with HCM. Eighty-eight patients with HCM (71 men, 17 women) were enrolled in the study. IR was estimated using the homeostasis model assessment (HOMA) index. Echocardiographically determined left atrial (LA) dimension was measured as a marker of LA size. The ratio of trasmitral early LV filling velocity to early diastolic mitral annulus velocity (E/e') was also measured as a marker of LV diastolic function. Twenty-seven patients (31%) had IR. Multivariate logistic regression analyses showed that independent determinants of AF were increased LA size [odds ratio (OR) 3.5, 95% confidence interval (CI) 1.2-9.8] and impaired LV diastolic function [OR 4.6, 95% CI 1.6-12.8]. The strongest determinant of LA size was the HOMA index (p = 0.0005). Similarly, the HOMA index (p = 0.0019) was an independent determinant of LV diastolic function. IR is highly prevalent among non-diabetic patients with HCM. A possible mechanism by which IR affects the development of AF is mediated through its association with increased LA size or impaired LV diastolic function. IR may be an important underlying mechanism for the genesis of AF in HCM.