Differences In Left Atrial Size Research Articles

Intermittent hypoxia is significantly associated with low-voltage areas in patients with atrial fibrillation complicated by obstructive sleep apnea

Abstract Background Obstructive sleep apnea (OSA) is one of risk factors for atrial fibrillation (AF); however, how OSA affects the structural and electrical atrial remodeling is not well described. This study aimed to determine the association of OSA with left atrial (LA) size and LA low-voltage area (LVA), a known arrhythmogenic substrate for AF. Methods Eighty-three patients undergoing catheter ablation of AF (forty-nine with OSA [apnea–hypopnea index: AHI ≥ 5/h] and thirty-four control patients without OSA by full polysomnography or portable monitor) were studied. In all cases, LA maps were created using a three-dimensional electro-anatomical mapping system in sinus rhythm or pacing from the right atrium. LVA was defined as a bipolar voltage < 0.5 mV. %LVA is defined as ratio of LVA to LA area. Results LVA and %LVA were larger in OSA group as compared to Control group (6.0 ± 6.6 vs. 2.6 ± 3.2 cm2, P = 0.003 and 7.5 ± 8.5 vs. 3.5 ± 4.6 %, P = 0.008, respectively). On the other hand, there was no difference in LA size between the two groups. In addition, 3% oxygen desaturation index (ODI) was significantly correlated with %LVA (r = 0.282, P = 0.010), but not with LA size (r = 0.053, P = 0.637). Multiple regression analysis demonstrated that 3%ODI ≥ 30 (3.088, 1.078-8.851, P = 0.036) was significantly associated with %LVA after adjustment. Conclusion In patients with AF complicated by OSA, significant enlargement of the LVA was observed, but there was no evidence of enlargement in LA size. Intermittent hypoxia may be one of the mechanisms of this atrial electro-anatomical remodeling.figure 1figure 2

Racial Disparities in Atrial Fibrillation After Coronary Artery Bypass: Impact of Left Atrial Volume

BackgroundPrior studies have demonstrated a lower prevalence of postoperative atrial fibrillation (POAF) in Black, Hispanic, Asian, and Native American patients compared with White cohorts after coronary artery bypass grafting. We hypothesized that preoperative differences in left atrial size may explain this disparity. MethodsWe assessed the incidence of new POAF in 1218 patients (215 minority patients and 1003 White patients) undergoing isolated, first-time coronary artery bypass grafting from January 2017 through September 2022. Preoperative left atrial volume index (LAVi) was assessed by transthoracic echocardiography. ResultsMinority patients were younger and more likely to be female, with more comorbidities, including diabetes, prior stroke, and dialysis. There was no difference in postoperative mortality, stroke, renal failure, or reoperation for bleeding between minority and White patients. Whereas minority patients had higher blood product use and longer intensive care unit and postoperative lengths of stay, they experienced a lower incidence of new POAF (19.5% [42/215] vs 29.5% [292/1003]; P = 0.02). Mean LAVi was similar between minority and White patients (30.3 ± 12.6 mL/m2 vs 29.9 ± 10.1 mL/m2; P = .64). However, for White patients, LAVi was higher for patients with POAF than for patients without POAF (31.3 ± 10.9 mL/m2 vs 29.3 ± 9.7 mL/m2; P = .007), whereas for minority patients, LAVi was similar for patients with and without POAF (30.7 ± 26.0 mL/m2 vs 30.3 ± 11.7 mL/m2; P = .84). ConclusionsDespite more comorbidities, higher transfusion rates, and longer length of stay, minority patients had a significantly lower incidence of POAF compared with White patients but no difference in preoperative LAVi. Larger LAVi may be predictive of POAF in White patients but not in minority patients.

RENIN-ANGIOTENSIN-ALDOSTERONE BLOCKADE AND ITS PREDICTION OF LATE RECURENCE OF ATRIAL FIBRILLATION AFTER RADIOFREQUENCY ABLATION

Objective: Hypertension is one of the main triggers of atrial fibrillation. Patients with hypertension have 1.7 times higher risk of developing atrial fibrillation. Opinions differ on the use of RAAS blockers in atrial fibrillation. The aim is to evaluate the effect of RAAS blockers in the prevention of atrial fibrillation on the post-ablation prognosis of the patient. Design and method: A retrospective analysis of 221 patients who underwent radiofrequency ablation of atrial fibrillation at the First Department of Internal Medicine - Cardioangiology of St. Anne's University Hospital in Brno from 1 January to 31 December 2019 was performed. Recurrence within the first three months was designated as early, and in the following months as late. Results: The median age of the study population (N = 221) was 63 years, with 67.4% of men. According to pre-ablation transesophageal echocardiography, the mean left atrial dimension was 45.3mm and left ventricular ejection fraction was 59.8%. Among the comorbidities, hypertension (63.3%) and dyslipidaemia (41.6%) were the most common, followed by diabetes mellitus (14.0%), ischemic heart disease (7.2%), history of stroke (6.3%), chronic obstructive pulmonary disease (5.0%). 33.0% had a history of nicotinism. Among the baseline antihypertensive groups, beta-blockers were the most represented (69.2%) followed by angiotensin-converting enzyme inhibitors (37.5), angiotensin-receptor blockers (20.4%), calcium channel blockers (32.1%) and diuretics (32.1%). There was not a significant difference in the representation of each group of antihypertensives between the populations. n the group of patients treated with ACEis/ARBs (57.9%), the mean blood pressure resulting from pre- and post-ablation measurements was the same 149/81mm Hg. No significant differences in left atrial size or capture of early or late postablation recurrence (HR 1.26, 95% CI 0.84-1.90, p = 0.265) were detected in the RAAS inhibitor group relative to patients without ACEis/ARBs in therapy. Conclusions: Conventionally administered ACEis/ARBs before ablation procedure did not lead to a reduction in the detection of late postablation recurrence of atrial fibrillation. Despite the documented benefit of RAAS blocker therapy in atrial fibrillation patients, their routine administration before ablation procedure aimed at improving postablation prognosis was not evaluated as justified.

PO-02-135 DOES LA SIZE PREDICT OUTCOMES IN AF AND SYSTOLIC HEART FAILURE?

Significant left atrial (LA) enlargement often accompanies heart failure with reduced ejection fraction (HFrEF) and may determine the success of AF ablation. However, the impact of LA size on long-term outcomes remains unclear. We aim to determine the relationship between LA size and AF recurrence in patients with normal LV function (NLV) and HFrEF following AF ablation. Consecutive patients undergoing index AF ablation across 11 centres were stratified according to baseline LVEF (<50% or >50%). The impact of baseline LA size on 12-month AF recurrence was determined utilising continuous remote rhythm monitoring to detect arrhythmia recurrence and quantify AF burden. 360 patients were included (NLV=237, HFrEF=123). The HFrEF group (mean LVEF 34.9±8.3%) were younger (62±10 vs 65 ± 9 years, p=0.020), with larger LA size (LAVI 54.6±16.5ml/m2 vs 45.4±14.1ml/m2, p<0.001). Despite differences in LA size, freedom from AF was similar in those with and without HF (56% vs 54% respectively, Log Rank p=0.621, figure 1a). Similarly, AF burden did not differ between groups (median burden HFrEF 0% (0-1.1); NLV 0 (0-2.5), p=0.195). An age-matched 1:1 comparison of NLV and HFrEF (N=246) demonstrated no impact of baseline LA size on arrhythmia recurrence (p=0.579), despite larger LA in those with HFrEF (LAVI 54.6±16.5 vs NLV 45.0±15.0, p=0.0002). LA enlargement did not predict arrhythmia recurrence (HR 1.400, 95% CI 0.952-2.057, p=0.086) regardless of HF status (figure 1b). At 12 months, LV function normalised in 80% (LVEF>50%) of those with HFrEF (ΔLVEF: +19±13%, p<0.001) with a significant reduction in LA size (54.6±16.5 to 44.7±14.6ml/m2, p<0.001), comparable in those with and without AF recurrence (p=0.819). Baseline LA enlargement did not influence AF recurrence in those with or without LV recovery (HR 1.622 95% CI 0.702-3.748, p=0.258). LA enlargement did not determine the outcome of AF ablation in those with and without HFrEF. LA size is less useful in guiding patient selection for AF ablation in HFrEF

Intrinsic Atrial Myopathy Precedes Left Ventricular Dysfunction and Predicts Atrial Fibrillation in Lamin A/C Cardiomyopathy.

In Lamin A/C (LMNA) cardiomyopathy, atrial fibrillation (AF) commonly occurs before dilated cardiomyopathy, and the ability to predict its incidence is limited. We hypothesized that left atrial (LA) echocardiographic phenotyping can identify atrial myopathy and harbingers of AF. Echocardiograms from patients with pathogenic or likely pathogenic variants in LMNA (n=77) with and without reduced left ventricular ejection fraction (LVEF, <50%) were compared to healthy individuals (n=70) and patients with Titin truncating variant cardiomyopathy (TTNtv) (n=35) with similar LVEF, sex, and age distributions. Echocardiographic analysis, blinded to genotype, included strain and volumetric measures of left ventricular and atrial function. The primary outcome was incident AF. At baseline, 43% of the patients with pathogenic or likely pathogenic LMNA variants had a history of AF, including 26% of those with LVEF ≥50%. Compared with healthy subjects, the patients with pathogenic or likely pathogenic LMNA variants and LVEF ≥50% had reduced LA contractile strain (LMNA, 11.8±6.1% versus control, 15.0±4.2%; P=0.003). Compared to LVEF-matched (TTNtv) patients, the patients with pathogenic or likely pathogenic LMNA variants and LVEF <50% displayed no difference in LA size, but a worse LA contractile dysfunction (6.4±4.7% versus 12.6±9.6%; P=0.02). Over a median follow-up of 2.8 (1.2-5.7) years, LA contractile strain was the only significant predictor of AF in multivariable Cox regression (hazard ratio, 4.0 [95% CI, 1.04-15.2]). LMNA cardiomyopathy is associated with early intrinsic atrial myopathy reflected by high AF prevalence and reduced LA contractile strain, even in the absence of LV dysfunction and LA dilation. Whether LA strain can be used as a monitoring strategy to detect and mitigate AF complications requires validation.

Association of Childhood Blood Pressure with Left Atrial Size and Function: Study of High Blood Pressure in Pediatrics–Adult Hypertension in Youth (SHIP AHOY)

To evaluate the cross-sectional association of cardiovascular disease risk factors with left atrial (LA) size and function among healthy youth, aged 11-18years, with a wide range of blood pressures (BPs). Echocardiographic images of youth enrolled in the Study of High Blood Pressure in Pediatrics: Adult Hypertension Onset in Youth study were analyzed for LA measurements. The association of casual BP, ambulatory BP, and other cardiovascular disease risk factors with LA size and function were determined using descriptive statistics and multivariable regression. Regression models adjusting for age, sex, race, and body mass index z score determined the independent association between ambulatory systolic BP indices (mean systolic BP/50th %ile systolic BP) and BP phenotypes with LA outcomes while exploratory analyses investigated for additional predictors of LA outcomes. The study population consisted of 347 youth: median age 15.7years, 60% male and 40% non-White. Greater-risk casual systolic BP groups had worse cardiometabolic profiles but no differences in LA size and function. Each 0.1 increase in ambulatory systolic BP day or night index was associated with a 9.9mL/m2 increase in LA volume/body surface area (LAV/BSA; 95th% CI 2.8-17.0, P=.006) and a 6.8mL/m2 increase in LAV/BSA (95th% CI 0.8-12.8, P=.03), respectively. Ambulatory hypertension was associated with greater odds of abnormal LAV/BSA, defined as >75th %ile (2014 ambulatory BP monitoring criteria: OR 3.2 [95th% CI 1.4-7.2; P=.002]; 2022 ambulatory BP monitoring criteria: OR 2.1 [95th% CI 1.0-4.1; P=.008]). Increasing ambulatory systolic BP and ambulatory hypertension are independently associated with LAV/BSA.

Differences in Left Atrial Size and Function and Supraventricular Ectopy Between Black and White Participants in the ARIC Study.

BackgroundBlack Americans have more atrial fibrillation risk factors but lower atrial fibrillation risk than White Americans. Left atrial (LA) enlargement and/or dysfunction, frequent atrial tachycardia (AT), and premature atrial contractions (PAC) are associated with increased atrial fibrillation risk. Racial differences in these factors may exist that could explain the difference in atrial fibrillation risk.Methods and ResultsWe included 2133 ARIC (Atherosclerosis Risk in Communities) study participants (aged 74±4.5 years[mean±SD], 59% women, 27% Black participants) who had echocardiograms in 2011 to 2013 and wore the Zio XT Patch (a 2‐week continuous heart monitor) in 2016 to 2017. Linear regression was used to analyze (1) differences in AT/day or PAC/hour between Black and White participants, (2) differences in LA measures between Black and White participants, and (3) racial differences in the association of LA measures with AT or PAC frequency. Compared with White participants, Black participants had a higher prevalence of cardiovascular risk factors and disease, lower AT frequency, greater LA size, and lower LA function. After multivariable adjustments, Black participants had 37% (95% CI, 24%–47%) fewer AT runs/day than White participants. No difference in PAC between races was noted. Greater LA size and reduced LA function are associated with more AT and PAC runs; however, no race interaction was present.ConclusionsDifferences in LA measures are unlikely to explain the difference in atrial fibrillation risk between Black and White individuals. Despite more cardiovascular risk factors and greater atrial remodeling, Black participants have lower AT frequency than White participants. Future research is needed to elucidate the protective mechanisms that confer resilience to atrial arrhythmias in Black individuals.

Independent effect of visceral fat on left atrial phasic function in the general population

Background and aimsObesity increases the risk for atrial fibrillation (AF), although the impact of abdominal fat distribution on left atrial (LA) morphology and functional remodeling remains unclear. This study aimed to investigate whether increased abdominal adiposity is independently associated with impaired LA function and/or LA enlargement in a sample of the general population and to evaluate the role of adipokines in this association. Methods and resultsThe study cohort consisted of 527 participants (362 men; 57 ± 10 years) without overt cardiac disease who underwent laboratory testing, abdominal computed tomographic examination and echocardiography. Abdominal adiposity was quantitatively assessed as visceral fat area (VFA) and subcutaneous fat area (SFA) at the level of the umbilicus. Speckle-tracking echocardiography was performed to assess LA phasic function including reservoir, conduit and pump strain. LA reservoir and conduit strain decreased with increasing VFA quartiles (both p < 0.05), whereas no significant differences were observed in LA volume index and pump strain. When stratified by SFA, there were no significant differences in LA size and function across the quartiles. In multivariable analysis, VFA was significantly associated with LA conduit strain independent of cardiovascular risk factors, and pertinent laboratory and echocardiographic parameters (standardized β = −0.136, p = 0.019). VFA was correlated with serum adiponectin level (r = −0.51, p < 0.001), but there was no association between adiponectin level and three LA phasic strains. ConclusionIn a sample of the general population, VFA accumulation was independently associated with worse LA conduit strain, which may be involved in the pathophysiological mechanism of obesity-related AF.

Normal Values of Left Atrial Size and Function and the Impact of Age: Results of the World Alliance Societies of Echocardiography Study

Left atrial (LA) evaluation includes volumetric and functional parameters with an abundance of diagnostic and prognostic implications. Solid normal reference ranges are compulsory for accurate interpretation in individual patients, but previous studies have yielded mixed conclusions regarding the effects of age, sex, and/or race. The present report from the World Alliance Societies of Echocardiography study focuses on two-dimensional (2D) and three-dimensional (3D) measures of LA structure and function, with subgroup analysis by age, sex, and race. Transthoracic 2D and 3D echocardiographic images were obtained in 1,765 healthy individuals (901 men, 864 women) evenly distributed among age subgroups: 18 to 40years (n=745), 41 to 65years (n=618), and >65years (n=402); the racial distribution was 38.4% white, 39.9% Asian, and 9.7% black. Images were analyzed using dedicated LA analysis software to measure LA volumes and phasic function from 3D volume and 2D strain curves. Three-dimensional maximum and minimum LA volumes adjusted for body surface area were nearly identical for men and women, but women demonstrated higher 3D total and passive emptying fractions (EFs). Two-dimensional reservoir strain was similar for both sexes. Age was associated with an incremental rise in LA volumes alongside characteristic shifts in functional indices. Total 2D EF and reservoir and conduit strain varied inversely with age, counteracted by higher booster strain, with a greater magnitude of effect in women. Active 3D EF was significantly higher, while total and passive EFs decreased with age. Interracial differences were noted in LA volumes, without substantial differences in functional indices. Although similar normal values for LA volumes and strain can be applied to both sexes, meaningful differences in LA size occur with aging. Indices of function also shift with age, with a compensatory rise in booster function, which may serve to counteract observed lower total and passive EFs. Defining age-associated normal values may help differentiate age-associated "healthy" LA aging from pathologic processes.

Quantification of left atrial contractile function using two-dimensional speckle tracking echocardiography in horses after conversion of atrial fibrillation to sinus rhythm

Introduction/ObjectivesIn horses, persistent atrial dysfunction is a prognostic indicator of recurrence of atrial fibrillation (AF). The objective of this study was to quantify left atrial (LA) contractile function in Warmblood horses after successful cardioversion of AF to sinus rhythm, using standard two-dimensional echocardiography (2DE) and two-dimensional speckle tracking (2DST) analyses, and to provide proof-of-concept for use of 2DST to detect LA contractile dysfunction in horses. Animals, materials, and methodsNineteen Warmblood horses with AF and successful transvenous electrical cardioversion (TVEC) or medical cardioversion using quinidine sulfate (QS) were included. Echocardiography was performed at 24 hr, 72 hr, and 1–6 months after cardioversion. Conventional 2DE-derived indices of LA size and function and global longitudinal strain (SL) and longitudinal strain rate (SRL) during LA contractile function were measured to detect differences in LA size and function over time and between treatment modalities. The association between 2DE-derived indices and global SL and SRL, respectively, and the agreement of the variables to detect LA dysfunction were assessed. ResultsGlobal SL and SRL, as well as active LA fractional area change (FAC) identified cases with LA dysfunction after TVEC and QS cardioversion and proved useful to demonstrate LA functional recovery over time. Agreement between active LA FAC and SL and SRL, respectively, to diagnose atrial dysfunction was substantial to fair at 24 hr after cardioversion and decreased with time. ConclusionThis study shows that 2DST is useful to quantify LA contractile dysfunction in horses after cardioversion of AF.

Abstract 14520: Differences in Left Atrial Size and Function and Supraventricular Arrhythmias Between Blacks and Whites in the Atherosclerosis Risk in Communities (ARIC) Study: Implications for AF Pathogenesis

Introduction: Black Americans have more atrial fibrillation (AF) risk factors but lower AF risk than whites. Left atrial (LA) enlargement, impaired LA function, frequent premature atrial contractions (PAC), and atrial tachycardia (AT) are risk factors for AF. Racial differences in LA size and function, PAC, or AT may exist that could explain the difference in AF risk. Hypothesis: Whites have higher PAC and AT frequency than blacks. Additionally, whites have larger LA size and lower LA function than blacks, which may contribute to the racial difference in AF. Methods: We included 1,623 ARIC participants free of AF who had 2D-echocardiograms at visit 5 (2011-2013) and wore a 2-week continuous heart monitor, the Zio ® XT Patch, at visit 6 (2016-2017). Weighted linear regression was used to analyze the association of race with LA size and function, as well as runs of AT per day and PAC per hour. Results: At visit 5, participants were 74 (4) years old, 58% were female, and 26% were black. AT runs were detected in 87% of blacks and 92% of whites, respectively (p=0.002). Among participants with &gt;0 runs of AT per day (n=1480), blacks had 48% (95% CI: 21%-66%) fewer runs of AT per day than whites after adjustment for cardiovascular (CV) risk factors † . There was no significant difference in PAC frequency between blacks and whites. After adjusting for age and sex, blacks had greater LA size and lower LA function than whites; these differences attenuated after adjusting for CV risk factors (Table). Conclusion: Blacks have greater age and sex-adjusted abnormality in LA size and function than whites, likely due to higher prevalence of CV risk factors. Yet, blacks have lower propensity for AT. More research is needed to elucidate the mechanisms underlying the resistance to atrial arrhythmogenesis in blacks despite greater adverse LA remodeling.

Prospective Evaluation of Clinico-Pathological Predictors of Postoperative Atrial Fibrillation: An Ancillary Study From the OPERA Trial.

Postoperative atrial fibrillation (POAF) occurs in 30% to 50% of patients undergoing cardiac surgery and is associated with increased morbidity and mortality. Prospective identification of structural/molecular changes in atrial myocardium that correlate with myocardial injury and precede and predict risk of POAF may identify new molecular pathways and targets for prevention of this common morbid complication. Right atrial appendage samples were prospectively collected during cardiac surgery from 239 patients enrolled in the OPERA trial (Omega-3 Fatty Acids for Prevention of Post-Operative Atrial Fibrillation), fixed in 10% buffered formalin, and embedded in paraffin for histology. We assessed general tissue morphology, cardiomyocyte diameters, myocytolysis (perinuclear myofibril loss), accumulation of perinuclear glycogen, interstitial fibrosis, and myocardial gap junction distribution. We also assayed NT-proBNP (N-terminal pro-B-type natriuretic peptide), hs-cTnT, CRP (C-reactive protein), and circulating oxidative stress biomarkers (F2-isoprostanes, F3-isoprostanes, isofurans) in plasma collected before, during, and 48 hours after surgery. POAF was defined as occurrence of postcardiac surgery atrial fibrillation or flutter of at least 30 seconds duration confirmed by rhythm strip or 12-lead ECG. The follow-up period for all arrhythmias was from surgery until hospital discharge or postoperative day 10. Thirty-five percent of patients experienced POAF. Compared with the non-POAF group, they were slightly older and more likely to have chronic obstructive pulmonary disease or heart failure. They also had a higher European System for Cardiac Operative Risk Evaluation and more often underwent valve surgery. No differences in left atrial size were observed between patients with POAF and patients without POAF. The extent of atrial interstitial fibrosis, cardiomyocyte myocytolysis, cardiomyocyte diameter, glycogen score or Cx43 distribution at the time of surgery was not significantly associated with incidence of POAF. None of these histopathologic abnormalities were correlated with levels of NT-proBNP, hs-cTnT, CRP, or oxidative stress biomarkers. In sinus rhythm patients undergoing cardiac surgery, histopathologic changes in the right atrial appendage do not predict POAF. They also do not correlate with biomarkers of cardiac function, inflammation, and oxidative stress. Graphic Abstract: A graphic abstract is available for this article.

Factors responsible for left atrial clot formation in patients with mitral stenosis and normal sinus rhythm

Background: The objective of the study was to investigate the factors responsible for left atrial (LA) clot formation in patients with mitral valve stenosis in normal sinus rhythm.Methods: 79 patients (43 males and 36 females) were included in the study. 9 patients with mitral stenosis in normal sinus rhythm had LA clot or LA smoke in echocardiography included in Group A and rest of 70 patients in Group B. LA size, gradient across mitral valve and mitral valve surface area was studied and compared in patients with or without LA clot/smoke.Results: Mean LA size was 4.8 (±0.5) and 4.6 (±0.7) in group A and B respectively with (p=0.304) and mean valve gradient was 11.6 (±2.8) and 10.6 (±3.5) in group A and B respectively with (p=0.507), the difference was not significant in both. Mean mitral valve area was 1.01 (±0.3) and 1.12 (±0.5) in group A and B (p=0.36), the difference was not significant.Conclusions: Study concluded that there was no significant difference in LA size, valve gradient and mitral valve area in patients with or without LA clot having mitral valve stenosis in normal sinus rhythm. Patients with LA clot warrant measures to prevent thromboembolic episodes.

P wave indices, heart rate variability and anthropometry in a healthy South Asian population

BackgroundSouth Asians have a low prevalence of atrial fibrillation (AF) in comparison with White Europeans despite a higher burden of hypertension, diabetes mellitus and coronary artery disease. The reason for this disparity is unclear but may relate to electrophysiological or structural differences within the atria or variations in autonomic function. We aimed to assess these areas using a range of non-invasive cardiac investigations.MethodsA prospective cohort study was performed on 200 South Asian and 200 Caucasian healthy volunteers aged 18–40 years. All subjects underwent electrocardiography (ECG), echocardiography and anthropometric measurements. Eighty subjects in each cohort underwent 24 hour ambulatory ECG and fifty subjects in each cohort underwent exercise testing.ResultsCompared with White Europeans, South Asians were of a smaller height with lower lean body mass and smaller left atrial size. They had reduced P wave dispersion and P wave terminal force in lead V1. South Asians had a lower burden of supraventricular ectopy. They had a higher mean heart rate and South Asian males had lower heart rate variability, suggestive of sympathetic predominance. Exercise capacity was lower in South Asians.ConclusionsSouth Asians have differences in left atrial size, P wave indices, burden of supraventricular ectopy, heart rate, heart rate variability and anthropometric measurements. These differences may relate to variations in atrial morphology, atrial electrophysiology and autonomic function and might help to explain why South Asians are less susceptible to developing AF.

Mechanisms of Left Atrial Enlargement in Obesity

Left atrial (LA) enlargement is common in obesity. We sought to determine the influence of ventricular (LV) remodeling on LA size in obesity. We studied 50 otherwise healthy obese subjects (body mass index 37.2 ± 4.6 kg/m2, 50 ± 6 years) and 58 age and gender-matched nonobese controls (body mass index 26.2 ± 2.9 kg/m2, 52 ± 5 years). Diastolic function, relative wall thickness (RWT), and LV mass were assessed using echocardiography. LA and LV volume was measured by 3D-echocardiography. Primary outcome was the ratio of LA volume indexed to LV volume in obese and control subjects. Obese subjects had substantially larger LA volumes compared with control subjects (61.0 ± 16.9 vs 38.9 ± 9.2 ml, p < 0.0001). When scaled to body size or lean mass, differences in LA size persisted. However, when indexed to LV end-diastolic volume, LA volumes between control and obese subjects were comparable (obese vs controls: 0.44 ± 0.15 vs 0.42 ± 0.10, p = 0.46). A small subset of obese subjects (26%) had LA volume markedly out of proportion to LV volume (LA/LV volume ratio ≥0.5) and displayed concentric LV remodeling with larger RWT and LV mass compared with obese subjects with LA/LV <0.5 (RWT: 0.46 ± 0.09 vs 0.36 ± 0.06, p < 0.0001; LV mass: 79 ± 18 vs 62 ± 13 g/m2 p < 0.01). In conclusion, LA enlargement in patients with obesity generally occurs commensurate with LV enlargement and parallels eccentric LV remodeling. LA enlargement out of proportion to LV size is associated with increased RWT and mass. This unique signature may identify obese subjects with pathologic LA remodeling.

Abstract WP265: Racial Differences in Left Atrial Size Among Patients With Ischemic Stroke

Introduction: Blacks in the U.S. face twice the risk of ischemic stroke as whites, and this disparity is not fully explained by established stroke risk factors. Although atrial fibrillation (AF) is a major risk factor for stroke, blacks are less often diagnosed with AF than whites. It is unclear whether this paradox exists because AF is less thoroughly ascertained in blacks compared to whites or because blacks have less predisposing substrate and thus a truly lower risk of AF. Hypothesis: Based on our prior work, we hypothesized that black patients with ischemic stroke less often have left atrial enlargement, a major predisposing factor for AF. Methods: We compared left atrial size in black versus white patients in the Greater Cincinnati/Northern Kentucky Stroke Study, a study of racial disparities in stroke incidence in a nationally representative population of 1.3 million. We obtained reports of echocardiograms performed for stroke evaluation among patients in the 2010 and 2015 study periods. Patients with known AF or atrial flutter were excluded. Investigators blinded to patients’ characteristics abstracted left atrial diameter from echocardiogram reports. Linear regression was used to examine the association between race and left atrial diameter after adjustment for demographics, body mass index, and comorbidities. Results: Among 2,980 cases of ischemic stroke without AF, the median age was 66 years, 52% were female, and 30% were black. The overall mean left atrial diameter was 3.65 (±0.69) cm. Despite a higher burden of vascular risk factors and comorbidities, blacks had significantly smaller left atrial diameters (mean difference, -0.10 cm; 95% CI, -0.04 to -0.17 cm). This difference persisted after adjustment for demographics, comorbidities, and body mass index (adjusted mean difference, -0.15 cm; 95% CI, -0.09 to -0.21 cm). Conclusions: In a population-based sample, we found that black patients with ischemic stroke had smaller left atrial size than white patients. Our results suggest that the paradox of greater stroke risk but lower AF risk in blacks compared with whites at least partly stems from a lesser degree of AF substrate in blacks.

Racial Differences in Left Atrial Size: Results from the Coronary Artery Risk Development in Young Adults (CARDIA) Study.

Whites have an increased risk of atrial fibrillation (AF) compared to Blacks. The mechanism underlying this association is unknown. Left atrial (LA) size is an important AF risk factor, and studies in older adults suggest Whites have larger LA diameters. However, because AF itself causes LA dilation, LA size differences may be due to greater subclinical AF among older Whites. We therefore assessed for racial differences in LA size among young adults at low AF risk. The Coronary Artery Risk Development in Young Adults (CARDIA) study enrolled White and Black participants between 18 and 30 years of age. LA diameter was measured in a subset of participants using echocardiography at Year 5 (n = 4,201) and Year 25 (n = 3,373) of follow up. LA volume was also assessed at Year 5 (n = 2,489). Multivariate linear regression models were used to determine the adjusted association between race and LA size. In unadjusted analyses, mean LA diameter was significantly larger among Blacks compared to Whites both at Year 5 (35.5 ± 4.8 mm versus 35.1 ± 4.5 mm, p = 0.01) and Year 25 (37.4 ± 5.1 mm versus 36.8 ± 4.9 mm, p = 0.002). After adjusting for demographics, comorbidities, and echocardiographic parameters, Whites demonstrated an increased LA diameter (0.7 mm larger at Year 5, 95% CI 0.3–1.1, p<0.001; 0.6 mm larger at Year 25, 95% CI 0.3–1.0, p<0.001). There was no significant association between race and adjusted Year 5 LA volume. In conclusion, in a young, well-characterized cohort, the larger adjusted LA diameter among White participants suggests inherent differences in atrial structure may partially explain the higher risk of AF in Whites. The incongruent associations between race, LA diameter, and LA volume suggest that LA geometry, rather than size alone, may have implications for AF risk.

The differences in left atrial function between ischemic and idiopathic dilated cardiomyopathy patients: A two-dimensional speckle tracking imaging study.

To evaluate left atrial (LA) function in patients with ischemic (ICM) or idiopathic dilated (DCM) cardiomyopathy via two-dimensional speckle-tracking imaging. We measured the LA maximum volume, minimum volume, and volume before the atrial systole, and calculated total emptying volume, expansion index, active emptying volume, and fraction. We measured strain and strain rate during systole and late diastole using two-dimensional speckle-tracking imaging, and analyzed correlations between variables. We found no significant differences in LA size, left ventricle (LV) end-diastole diameter, LV ejection fraction (EF), E/A, E/e', deceleration time of the E wave, and effective mitral regurgitant orifice area between the DCM and the ICM group. However, the LA expansion index, active EF, systolic and late diastolic strain, and strain rate were lower in the ICM group (p < 0.05). The expansion index and active EF were positively correlated with the systolic strain rate and the absolute value of the late diastolic strain rate, respectively. LA basic echocardiographic variables did not reflect the differences between ICM and DCM patients, but the systolic and late diastolic strain, as well as the strain rate, were lower in DCM patients. Two-dimensional speckle-tracking imaging is a promising method to differentiate these patients. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 44:437-445, 2016.

Electrocardiographic P wave changes after thoracoscopic pulmonary vein isolation for atrial fibrillation

Changes in P wave duration (PWD) and P wave area (PWA) have been described following catheter ablation for atrial fibrillation (AF). We hypothesize that video-assisted thoracoscopic pulmonary vein isolation (VATS-PVI) for AF results in decrease of PWD, PWA and P wave dispersion, which may resemble reverse electrical remodeling of the atrium after restoration of sinus rhythm. VATS-PVI consisted of PVI and ganglionic plexus ablation in 29 patients (mean age, 59 ± 7years; 23 males; 17 paroxysmal AF) and additional left atrial lesions in patients with persistent AF. PWD and PWA were measured in ECG lead II, aVF and V2 of ECGs during sinus rhythm before, directly after, and 6months postprocedure. P wave dispersion was derived from the 12 lead ECG. Prior to VATS-PVI, PWD did not correlate with left atrial size and no difference in left atrial size was found between patients with paroxysmal or persistent AF (p = 0.27). Following VATS-PVI, PWD initially prolonged in all patients from 115 ± 4.6ms to 131 ± 3.6ms (p < 0.01) but shortened to 99 ± 3.2ms after 6months (p < 0.01). PWA was 5.60 ± 0.32mV*ms at baseline, 6.44 ± 0.32mV*ms post-VATS-PVI (P = NS), and 5.40 ± 0.28mV*ms after 6months (p = NS vs. baseline, p < 0.05 vs. post-VATS-PVI). P wave dispersion decreased in the persistent AF group from baseline 67 ± 3.3 to 64 ± 2.5ms post-VATS-PVI (p = 0.30) and to 61 ± 3.4ms after 6months (p < 0.05). PWD increases significantly directly after successful VATS-PVI in both groups. There was significant decrease in PWD after 6months. Similarly, P wave dispersion decreased in the persistent group. These changes suggest an immediate procedure related effect, but the later changes may represent reverse electrical atrial remodeling following cessation of AF.

How to achieve durable pulmonary vein isolation: Use the force

How to achieve durable pulmonary vein isolation: Use the force