Left atrial function: physiology, assessment, and clinical implications

Left atrial structure and function in atrial fibrillation: ENGAGE AF-TIMI 48

AIMS

The complex relationship between left atrial (LA) structure and function, electrical burden of atrial fibrillation (AF) and stroke risk is not well understood. We aimed to describe LA structure and function in AF.

METHODS AND RESULTS

Left atrial structure and function was assessed in 971 subjects enrolled in the echocardiographic substudy of ENGAGE AF-TIMI 48. Left atrial size, emptying fraction (LAEF), and contractile function were compared across AF types (paroxysmal, persistent, or permanent) and CHADS2 scores as an estimate of stroke risk. The majority of AF patients (55%) had both LA enlargement and reduced LAEF, with an inverse relationship between LA size and LAEF (R = -0.57, P < 0.001). With an increasing electrical burden of AF and higher CHADS2 scores, LA size increased and LAEF declined. Moreover, 19% of AF subjects had impaired LAEF despite normal LA size, and LA contractile dysfunction was present even among the subset of AF subjects in sinus rhythm at the time of echocardiography.

CONCLUSIONS

In a contemporary AF population, LA structure and function were increasingly abnormal with a greater electrical burden of AF and higher stroke risk estimated by the CHADS2 score. Moreover, LA dysfunction was present despite normal LA size and sinus rhythm, suggesting that the assessment of LA function may add important incremental information in the evaluation of AF patients.

CLINICAL TRIAL REGISTRATION

http://www.clinicaltrials.gov; ID = NCT00781391.

Effect of lifetime endurance training on left atrial mechanical function and on the risk of atrial fibrillation

BACKGROUND

Left atrium (LA) dilation and P-wave duration are linked to the amount of endurance training and are risk factors for atrial fibrillation (AF). The aim of this study was to evaluate the impact of LA anatomical and electrical remodeling on its conduit and pump function measured by two-dimensional speckle tracking echocardiography (STE).

METHOD

Amateur male runners >30 years were recruited. Study participants (n=95) were stratified in 3 groups according to lifetime training hours: low (<1500 h, n=33), intermediate (1500 to 4500 h, n=32) and high training group (>4500 h, n=30).

RESULTS

No differences were found, between the groups, in terms of age, blood pressure, and diastolic function. LA maximal volume (30±5, 33±5 vs. 37±6 ml/m(2), p<0.001), and conduit volume index (9±3, 11±3 vs. 12±3 ml/m(2), p<0.001) increased significantly from the low to the high training group, unlike the STE parameters: pump strain -15.0±2.8, -14.7±2.7 vs. -14.9±2.6%, p=0.927; conduit strain 23.3±3.9, 22.1±5.3 vs. 23.7±5.7%, p=0.455. Independent predictors of LA strain conduit function were age, maximal early diastolic velocity of the mitral annulus, heart rate and peak early diastolic filling velocity. The signal-averaged P-wave (135±11, 139±10 vs. 148±14 ms, p<0.001) increased from the low to the high training group. Four episodes of non-sustained AF were recorded in one runner of the high training group.

CONCLUSION

The LA anatomical and electrical remodeling does not have a negative impact on atrial mechanical function. Hence, a possible link between these risk factors for AF and its actual, rare occurrence in this athlete population, could not be uncovered in the present study.

Left atrium systolic and diastolic function assessment in hypertensive patients with preserved ejection fraction

Left atrium remodeling is a physiological response to pressure overload in hypertensive patients. The aim of this study is to determine the relationship between left atrium remodeling and left ventricle diastolic dysfunction in hypertensive patients with preserved systolic function.

MATERIALS AND METHODS

We conducted a prospective study on 96 hypertensive patients (48.75 ± 5.01 years, 50 men) and 96 healthy control subjects (48.17 ± 8.52 years, 56 men), whose data were all evaluated by echocardiography measuring left atrium volumes during the reservoir,conduit and pump phases. Standard indices reflecting left ventricular filling were also assessed.

RESULTS

Medium left atrium volume indexed for body surface was significantly higher in hypertensive patients – 30.87 (6.38) mL/m² vs.21.72 (2.52) mL/m². Indexed left atrium volume was strongly associated with left ventricle diastolic function (p <0.0001). When compared to normal subjects, patients with mild diastolic dysfunction had lower corrected passive emptying volumes ( p < 0.0001) and higher corrected active emptying volumes (p = 0.001), thus leading to similar corrected total emptying volumes ( p < 0.001). However, patients with moderate diastolic dysfunction had smaller active emptying volumes, but higher passive and total emptying volumes when compared to normal controls and patients with mild diastolic dysfunction.

CONCLUSIONS

Left atrium indexed volumes evaluation during the reservoir,conduit and pump phases proved to be essential for early diastolic dysfunction assessment in hypertensive patients.

Impaired leukocytes autophagy in chronic kidney disease patients

BACKGROUND

Proteins and cytoplasmic organelles undergo degradation and recycling via autophagy; its role in patients with chronic kidney disease (CKD) is still unclear. We hypothesize that impaired kidney function causes autophagy activation failure.

METHODS

We included 60 patients with stage 5 CKD and 30 age- and sex-matched healthy subjects as controls. Patients with conditions that could affect autophagy were excluded. Leukocytes were isolated and analyzed from peripheral blood samples collected after overnight fasting and 2 h after breakfast.

RESULTS

Overnight fasting induced conversion of microtubule-associated protein-1 light chain 3 I to II (γLC3) and increased mRNA levels of the autophagy-related gene 5 (Atg5) and Beclin-1 in healthy subjects, which were nearly absent in CKD patients (p = 0.0001). Moreover, no significant difference in autophagy activation was observed between CKD patients with or without hemodialysis. Correlation studies showed that γLC3 was negatively associated with the left atrium size. Changes in Atg5 transcript levels were negatively associated with the left ventricular end-diastolic diameter, and changes in Beclin-1 transcript levels were negatively associated with the mitral inflow E- and A-wave sizes.

CONCLUSION

These data suggest that CKD patients have impaired autophagy activation, which cannot be reversed with hemodialysis and is closely related to their cardiac abnormalities.

Left Atrial Function Predicts Heart Failure Events in Patients With Newly Diagnosed Left Ventricular Systolic Heart Failure During Short-Term Follow-Up

We assessed the effect of left atrial (LA) function index, LA ejection fraction, LA kinetic energy, and maximal LA volume on 6 months clinical outcome in patients with newly diagnosed systolic heart failure (HF). During a 36-month period, 179 consecutive patients (17% female, mean age 63 ± 14 years) were enrolled. During the follow-up, 46 patients had an event (32% event rate; 15 were fatal). Those with an adverse event were older, had lower creatinine clearance, advanced New York Heart Association stage, higher prevalence of ischemic HF, and lower values for right ventricle systolic wave in the tissue Doppler imaging evaluation, compared with those without an event. Multivariate analysis revealed that LA function and ischemic etiology of HF were the most significant prognostic indicators after index hospitalization. This study reveals the important role of LA function for the short-term prognosis of patients with newly diagnosed systolic HF in sinus rhythm.

Evaluation of biatrial size and functions by different echocardiographic parameters in patients with acute coronary syndromes

After acute coronary syndromes (ACS), cardiac remodelling affecting not only ventricles but also both atria is an important problem associated with an increased risk for adverse cardiovascular outcomes. However, it is usually underestimated to evaluate atrial size and functions. The aim of the present study is to compare left and right atrial size and functions in ACS patients with healthy controls during transthoracic echocardiography by means of diameter, area and volume measurements, and pulsed-wave tissue Doppler imaging (TDI). 150 ACS patients (128 male, 22 female) and 25 healthy controls (19 male, 6 female) were enrolled into the study. Of the ACS patients, 75 had ST-segment elevation myocardial infarction (STEMI) and 75 had non-STEMI. Biatrial diameters, areas, and volumes were measured from different echocardiographic views. Atrial total emptying fraction and expansion index values were calculated from volume measurements. By the pulsed-wave TDI of the atrial walls; peak systolic (S'), peak early diastolic (E'), and peak late diastolic (A') velocities were measured. Almost all left atrial parameters for diameter, area, and volume measurements were higher in ACS patients. Similarly, they had higher values for the same right atrial parameters. Left and right atrial total emptying fraction and expansion index values were lower in ACS patients than controls. All left and right atrial walls had lower S' and E' velocities in ACS patients. ACS cause important alterations in the biatrial size and functions evaluated by echocardiographic diameter, area and volume measurements, and pulsed-wave TDI.

Long-term follow-up of atrial function after cardioversion of atrial fibrillation in horses

Atrial fibrillation (AF) causes atrial electrical and contractile remodelling in horses. The aim of this study was to quantify left atrial (LA) contractile function and its time course of recovery after cardioversion of naturally-occurring AF in horses. The study population included 42 AF horses which were successfully treated using transvenous electrical cardioversion TVEC (n=39) or quinidine sulfate (n=3), with trivial or mild mitral regurgitation present in 25 horses. Thirty-seven healthy horses were used as controls. AF duration was estimated based on the history and previous examinations. Echocardiography was performed during general anaesthesia after TVEC (day 0) and on days 1, 2, 6 and then 7 weeks after cardioversion. The two-dimensional (2D) echocardiographic measurements included LA diameter, area and ejection phase indices such as fractional shortening. Atrial TDI measurements included peak myocardial velocity during atrial contraction (A), time to onset A, time to peak A and duration of A. During follow-up after cardioversion, atrial contractile function measured by 2D echocardiography and TDI gradually improved. At 7 weeks following cardioversion, TDI-based myocardial velocities returned to reference values. However, AF horses still showed significantly larger atrial dimensions, lower 2D ejection phase indices and prolonged TDI-based conduction time compared to the control group. In conclusion, AF-induced atrial contractile dysfunction gradually improves in the weeks following cardioversion, but at 7 weeks post-cardioversion, significant differences remain compared to healthy controls.

Left atrial functional remodeling in lone atrial fibrillation: a two-dimensional speckle tracking echocardiographic study

OBJECTIVE

The aim of this study was to assess left atrial (LA) functional remodeling in lone atrial fibrillation (LAF) patients via two-dimensional speckle tracking echocardiography (2DSTE).

METHODS

Forty-five paroxysmal LAF patients and 30 healthy controls underwent 2DSTE in sinus rhythm. Longitudinal LA strain/strain rate (LAS/LASR) of booster, reservoir, and conduit function in apical four- and two-chamber views were measured and averages of the 2 views were used.

RESULTS

The 2 groups had similarity in LA volume. LAS and LASR of the 3 phasic functions were reduced in patients. Comparing the 2 groups, LA booster strain (LASa) and strain rate were -12.31 ± 3.15 versus -15.30 ± 2.52% and -1.64 ± 0.51 versus -2.08 ± 0.48 1/sec, respectively, P < 0.05 for both. Multivariate regression confirmed that LAF was an independent determinant of LAS/LASR reduction. LASa was the most accurate parameter for differentiating LAF patients from controls (area under receiver operating characteristic curve, 0.763; cutoff value, -14.3%; sensitivity, 71.1% and specificity, 70.0%). Finally, LASa decrement was found to be the only significant predictor of early atrial fibrillation (AF) recurrence (odds ratio [OR], 1.39 per unit decrement; 95% CI, 1.02-1.89; P = 0.038).

CONCLUSIONS

Remodeling of LA booster pump, reservoir, and conduit function in LAF patients can be detected by 2DSTE before structural remodeling. Occurrence of LAF is associated with impairment of LA intrinsic myocardial properties. LASa can differentiate LAF patients and lower LASa is associated with early recurrence of AF after ablation.

Evaluation of atrial electromechanic delay and left atrial mechanical functions in the patients with secundum type atrial septal defect

AIM

The aim of our study was to evaluate atrial electromechanical delay (AEMD) and left atrial mechanical functions (LAMF) in the patients with secundum-type atrial septal defect (ASD).

METHOD

We included 72 patients with secundum type ASD in the study group and 35 gender and age-matched healthy volunteers for the control group. Maximal, minimal, and presystolic LA volumes were measured by modified Simpson method and indexed to the body surface area (BSA). Inter-AEMD, right and left intra-AEMD were measured from the lateral and septal mitral annulus and tricuspid annulus using tissue Doppler imaging (TDI).

RESULTS

The age, gender, systolic and diastolic blood pressure, heart rate (HR), BSA, and body mass index (BMI) parameters were not significantly different between the groups. Left atrial active and total emptying fractions and conduit volumes were significantly lower in the patients with ASD compared with the control group (P = 0.006, P = 0.001, and P = 0.032, respectively). Total emptying volume was increased in patients with ASD (P = 0.021). Passive emptying volume and fraction and active emptying volumes were not different significantly between the groups (P > 0.05). The left intraatrial, right intraatrial, and inter-AEMDs were significantly longer in the ASD group (P = 0.032, P = 0.013, and P = 0.003, respectively).

CONCLUSION

The left atrial reservoir and contractile pump functions are reduced; the left intraatrial, right intraatrial, and inter-AEMDs are increased in the patients with ASD.

Normal Values of Left Atrial Volume in Pediatric Age Group Using a Validated Allometric Model

Background—

Left atrial volume (LAV) increase is an indicator of diastolic dysfunction and a surrogate marker of significant left to right shunts. Normalization of LAV is currently performed by indexing to body surface area 1 (BSA 1 ). The indexed LAV thus derived does not account for the nonlinear relationship of physiologic variables to BSA and has not been tested for independence to body size. Our objective was to identify a valid allometric model for indexing LAV and use it to develop Z-scores in children.

Methods and Results—

LAV was measured in 300 normal subjects by echocardiography using the biplane area length method. LAV/BSA 1 had a residual relationship to BSA (r=0.52, P <0.0001). The allometric exponent (AE) derived for the entire cohort (1.27) using the least squares regression analysis also failed to eliminate the residual relationship to BSA (r=−0.15, P =0.01). Dividing the cohort in two groups with a BSA cut-off of 1 m 2 provided the best-fit allometric model. The AE for each group was 1.48 and 1.08 for BSA≤1 m 2 and >1 m 2 , respectively, and was validated against an independent sample. The mean indexed LAV±SD for BSA≤1 m 2 and >1 m 2 is 31.5±5.5 mL and 26.0±4.2 mL, respectively, and was used to derive Z-scores.

Conclusions—

This study demonstrates the fallacy of using “per-BSA 1 standards” for normalization of LAV in pediatrics. LAV/BSA 1.48 for children with BSA≤1 m 2 and LAV/BSA 1.08 for those with BSA>1 m 2 is accurate and can be used to derive Z-scores.

Severity of pseudofilling defect in the left atrial appendage on cardiac computed tomography is a simple predictor of the degree of left atrial emptying dysfunction in patients with chronic atrial fibrillation

OBJECTIVES

The purpose of our study was to investigate the clinical relevance of a pseudofilling defect in the left atrial appendage (LAA) detected on coronary computed tomography (CT) angiography (CCTA) as an indicator of impaired left atrial (LA) volumetric function in patients with chronic atrial fibrillation (CAF).

METHODS

Forty-two patients with CAF underwent CCTA. Quantitative and visual measurements of contrast enhancement of the LAA were performed, and they were correlated with results of CT volumetric functional analysis of the LA. Four volumetric parameters representing LA function were measured: maximum (LAVmax) and minimum volumes of the LA (LAVmin) through the entire cardiac cycle; LA emptying volume (LAEV); and LA emptying fraction (LAEF). All volumetric parameters were standardized by body surface area to adjust for variation in LA size among patients. For quantitative measurement, the CT attenuation was measured at the LAA and the LA to calculate an LAA/LA attenuation ratio. For visual measurement, contrast enhancement of the LAA was categorized into 3 groups; no filling defect, mild-to-moderate pseudofilling defect, and severe pseudofilling defect group. The Spearman correlation coefficient and the Kruskal-Wallis test were used for statistical analysis.

RESULTS

The LAA/LA ratio showed a strong positive correlation with LAEV (r = 0.52; P < 0.001) and LAEF (r = 0.69; P < 0.001). The LAEV in the no pseudofilling defect group and the mild-to-moderate and severe pseudofilling defect groups were 16.1 ± 8.4, 10.8 ± 3.1, and 6.7 ± 4.9 mL/m², respectively (P < 0.001). The LAEF in each group were 24.2 ± 13.8%, 12.0 ± 3.4%, and 6.9 ± 3.1%, respectively (P < 0.001).

CONCLUSIONS

The severity of pseudofilling defect in the LAA on CCTA could predict the degree of LA emptying dysfunction in patients with CAF.

Could successful cryoballoon ablation of paroxysmal atrial fibrillation prevent progressive left atrial remodeling?

Background

Radiofrequency catheter ablation of atrial fibrillation (AF) has been proved to be effective and to prevent progressive left atrial (LA) remodeling. Cryoballoon catheter ablation (CCA), using a different energy source, was developed to simplify the ablation procedure. Our hypothesis was that successful CCA can also prevent progressive LA remodeling.

Methods

36 patients selected for their first CCA because of nonvalvular paroxysmal AF had echocardiography before and 3, 6 and 12 months after CCA. LA diameters, volumes (LAV) and LA volume index (LAVI) were evaluated. LA function was assessed by: early diastolic velocities of the mitral annulus (Aa_sept, Aa_lat), LA filling fraction (LAFF), LA emptying fraction (LAEF) and the systolic fraction of pulmonary venous flow (PVSF). Detailed left ventricular diastolic function assessment was also performed.

Results

Excluding recurrences in the first 3-month blanking period, the clinical success rate was 64%. During one-year of follow-up, recurrent atrial arrhythmia was found in 21 patients (58%). In the recurrent group at 12 months after ablation, minimal LAV (38 ± 19 to 44 ± 20 ml; p < 0.05), maximal LAV (73 ± 23 to 81 ± 24 ml; p < 0.05), LAVI (35 ± 10 to 39 ± 11 ml/m²; p = 0.01) and the maximal LA longitudinal diameter (55 ± 5 to 59 ± 6 mm; p < 0.01) had all increased. PVSF (58 ± 9 to 50 ± 10%; p = 0.01) and LAFF (36 ± 7 to 33 ± 8%; p = 0.03) had decreased. In contrast, after successful cryoballoon ablation LA size had not increased and LA function had not declined. In the recurrent group LAEF was significantly lower at baseline and at follow-up visits.

Conclusions

In patients whose paroxysmal atrial fibrillation recurred within one year after cryoballoon catheter ablation left atrial size had increased and left atrial function had declined. In contrast, successful cryoballoon catheter ablation prevented progressive left atrial remodeling.

Left atrial function predicts heart failure hospitalization in subjects with preserved ejection fraction and coronary heart disease: longitudinal data from the Heart and Soul Study

OBJECTIVES

This study sought to determine whether left atrial (LA) dysfunction predicts heart failure (HF) hospitalization in subjects with preserved baseline ejection fraction (EF).

BACKGROUND

Among patients with preserved EF, factors leading to HF are not fully understood. Cross-sectional studies have demonstrated LA dysfunction at the time of HF, but longitudinal data on antecedent atrial function are lacking.

METHODS

We performed resting transthoracic echocardiography in 855 subjects with coronary heart disease and EF ≥50%. Left atrial functional index (LAFI) was calculated as ([LA emptying fraction × left ventricular outflow tract-velocity time integral] / [indexed LA end-systolic volume]), where LA emptying fraction was defined as (LA end-systolic volume--LA end-diastolic volume) / LA end-systolic volume. We used Cox models to evaluate the association between LAFI and HF hospitalization.

RESULTS

Over a median follow-up of 7.9 years, 106 participants (12.4%) were hospitalized for HF. Rates of HF hospitalization were inversely proportional to quartile (Q) of LAFI: Q1, 47 per 1,000 person-years; Q2, 18.3; Q3, 9.6; and Q4, 5.3 (p < 0.001). Each standard deviation decrease in LAFI was associated with a 2.6-fold increased hazard of adverse cardiovascular outcomes (unadjusted hazard ratio: 2.6, 95% confidence interval: 2.1 to 3.3, p < 0.001), and the association persisted even after adjustment for clinical risk factors, N-terminal pro-B-type natriuretic peptide, and a wide range of echocardiographic parameters (adjusted hazard ratio: 1.5, 95% confidence interval: 1.0 to 2.1, p = 0.05).

CONCLUSIONS

Left atrial dysfunction independently predicts HF hospitalization in subjects with coronary heart disease and preserved baseline EF. The LAFI may be useful for HF risk stratification, and LA dysfunction may be a potential therapeutic target.

[State of the art: new developments in cardiac imaging]

Cardiac imaging continues to reveal new anatomical and functional insights into heart disease. In echocardiography, both transesophageal and transthoracic three-dimensional imaging have been fully developed and optimized, and the value of the techniques that have increased our understanding of cardiac mechanics and ventricular function is well established. At the same time, the healthcare industry has released new devices onto the market which, although they are easier to use, have limitations that restrict their use for routine assessment. Tomography's diagnostic and prognostic value in coronary artery disease continues to increase while radiation exposure becomes progressively lower. With cardiac magnetic resonance imaging, myocardial injury and recovery in ischemic heart disease and following acute coronary syndrome can be monitored in exquisite detail. The emergence of new combined tomographic and gamma camera techniques, exclusively developed for nuclear cardiology, have improved the quality of investigations and reduced radiation exposure. The hybrid or fusion images produced by combining different techniques, such as nuclear cardiology techniques and tomography, promise an exciting future.

Assessment of left atrial dysfunction in obstructive sleep apnea patients with the two dimensional speckle-tracking echocardiography

BACKGROUND

The aim of this study was to compare left atrial (LA) longutidinal myocardial function in obstructive sleep apnea (OSA) patients with healthy individuals using two-dimensional speckle-tracking echocardiography method (2D-STE).

METHOD

Twenty one healthy individuals and 58 OSA patients were included. According to the AHI (apnea hypopnea index) patients were examined in mild, moderate and severe OSA groups. Images of the LA were acquired from the apical two- and four-chamber views. LA strain(LA(S)) and strain rate(LA(SR)) parameters [systolic (S), early diastolic (E), late diastolic (A) during atrial contraction] were assessed.

RESULTS

LA(S-S), LA(SR-S), LA(S-E) and LA(SR-E) values decreased with severity of OSA. Severe OSA patients have lower LA(S-S) and LA(SR-S) values (p < 0.03). While a difference in the LA(SR-E) value between groups was significant beginning with the moderate OSA group (p < 0.03), no LA(S-E) value differences were observed between moderate and mild OSA groups (p > 0.03). LA(S-A) and LA(SR-A) values were increasing with the disease severity up to moderate OSA. LA(S-A) and LA(SR-A) values of moderate OSA were greater than the mild OSA patients and healthy individuals (p < 0.03). These were lower in severe OSA than the moderate OSA (p < 0.03), however, they were greater than the healthy individuals (p < 0.03). The AHI was found to be negatively correlated with the LA(S-S), LA(SR-S) LA(S-E), LA(SR-E), whereas AHI was not correlated with the LA(S-A), LA(SR-A) values.

CONCLUSION

LA remodeling and dysfunction that accompany OSA can be detected in the subclinical stage with a detailed evaluation of active and passive functions of the LA using the 2D-STE method.

Effect of repeated radiofrequency catheter ablation on left atrial function for the treatment of atrial fibrillation

Radiofrequency catheter ablation (RFCA) is a potential curative treatment for atrial fibrillation (AF) by eliminating the arrhythmia and inducing left atrial (LA) reverse remodeling. However, the effect on LA function, especially after repeated procedures, has scarcely been studied. The aim of this study was to evaluate the impact of RFCA on LA size and function in patients with AF after a first and a repeated procedure. RFCA was performed in 154 patients with symptomatic drug-refractory AF. LA volumes and function were assessed with real-time 3-dimensional echocardiography before and 6 months after the procedure. Recurrence of the arrhythmia was defined as any atrial tachyarrhythmia lasting >30 seconds, clinically documented or by 24-hour Holter recording, after the first 6 months after ablation. Of the 154 patients, 104 (67%) required only a first ablation, and 50 (33%) required redo RFCA. LA volume was reduced after first RFCA (from 60 ± 19 to 52 ± 17 ml for 3-dimensional LA maximum volume, p <0.001, and from 38 ± 18 to 33 ± 15 ml for 3-dimensional LA minimum volume, p <0.000) without impairment of LA contractile function, measured as the active emptying percentage of total volume (39 ± 25% vs 43 ± 26%, p = NS). After repeated RFCA procedures, 3-dimensional LA maximum volume was reduced (from 57 ± 18 to 52 ± 18 ml, p = 0.04), also without further LA contractile function impairment (active emptying percentage of total volume) (36 ± 24% vs 36 ± 25% of total volume, p = NS). This effect was similar in paroxysmal and persistent AF. In conclusion, RFCA induces reductions in LA volumes without a deleterious impact on contractile function, even after repeated ablation.

A simplified method to determine left atrial volume and transport function using multi-slice computed tomography in patients with atrial fibrillation: comparison with transthoracic echocardiography

Although left atrial volumes (LAVs) and transport function can be accurately measured by multi-slice computed tomography (MSCT) during sinus rhythm, limited data are available for in patients with atrial fibrillation (AF). The aims of our study were to compare LAVs and function assessed by MSCT and transthoracic echocardiography (TTE) during AF, and to validate a simplified method to determine LAVs and functions using MSCT. A total of 150 consecutive AF patients who were scheduled to undergo catheter ablation were enrolled in this study. All subjects underwent MSCT and TTE on the same day. LAVs were measured by MSCT at every 10% of the R-R interval (10-phase analysis). LA transport function was assessed by measuring changes in LAVs. LAVs and functions were also assessed by TTE using a modified Simpson's method and an area-length method. Fifty patients were in sinus rhythm (SR) and 100 were in AF during their examinations. Although TTE underestimated the maximal LAV (LAV(max), by 38.3%) and overestimated the total LA emptying fraction (LAEF(total), by 61.1%) compared with MSCT, there were excellent correlations between TTE and MSCT. LAV(max) and the minimal LAV (LAV(min)) based on MSCT were determined at relatively constant cardiac phases during AF as well as SR (LAV(max); 40%, LAV(min); 100% of R-R interval, fixed-phase analysis). LAVs and LAEF(total) assessed by 10-phase analysis showed good correlations with those assessed by fixed-phase analysis (P < 0.001). LAVs and function assessed by MSCT correlated well with LAVs and functions assessed by TTE, irrespective of the underlying rhythm. Our results indicate that in the context of MSCT, fixed-phase analysis is a simple and reliable method to determine LAVs and function in patients with AF.