The role of the right atrium in development of postoperative atrial fibrillation: A speckle tracking echocardiography study

Echocardiographic Predictors of Postoperative Atrial Fibrillation After Cardiac Surgery: Assessing Atrial Mechanics for Risk Stratification

Postoperative atrial fibrillation (POAF) is a common complication after cardiac surgery, increasing morbidity and healthcare costs. This study aimed to identify echocardiographic predictors of POAF to improve risk stratification. A total of 131 patients undergoing cardiac surgery were analyzed and divided into two groups based on POAF occurrence. Echocardiographic analysis showed that patients with POAF had larger left and right atrial dimensions and impaired atrial function. Prolonged total atrial conduction time (TACT), reduced atrial emptying volumes, and contractile function were more common in the POAF group. Univariable analysis identified LAEF (χ2 = 71.8, p < 0.001), LAKE (χ2 = 70.1, p < 0.001), RATEF (χ2 = 65.7, p < 0.001), and RAAEF (χ2 = 66.8, p < 0.001) as significant predictors of POAF, each with an area under the curve (AUC) greater than 0.89. In multivariable analysis, LAKE (OR = 0.27, p < 0.001), hypertension (OR = 11.87, p = 0.035), left ventricular ejection fraction (OR = 1.08, p = 0.020), and peripheral vascular disease (OR = 40.28, p = 0.002) were independent predictors. The final model showed a significant discriminatory ability (AUC = 0.94). LAKE and clinical factors remained independent predictors after adjustment.

The association of right ventricular function with outcomes after cardiac surgery: a systematic review

PURPOSE

Assessment of right ventricular (RV) function is recommended as part of a comprehensive echocardiography exam, including before and after cardiac surgery. Nevertheless, the prognostic implications of various measures of RV function in patients undergoing cardiac surgery are not well characterized. Our goal was to conduct a focused systematic review to assess the association of quantitative parameters of RV function with postoperative outcomes in patients undergoing cardiac surgery.

METHODS

We conducted a systematic review of randomized controlled trials or observational studies in adult (≥ 18 yr) patients undergoing cardiac surgery with a reported echocardiogram within six months of surgery, intraoperatively, or shortly after surgery. We excluded case reports and case series. Databases included PubMed® and MEDLINE, and papers published from 1 January 1990 to 22 April 2024 were searched for. The primary predictors of interest were quantitative RV function parameters. The primary outcome of interest was postoperative mortality up to five years. The secondary outcome was all major adverse cardiac events (MACE).

RESULTS

We identified 7,187 potentially relevant studies, 27 of which were included; all of these were observational studies. Right ventricular fractional area change (RVFAC) was the most commonly reported parameter, but was inconsistently associated with mortality and MACE. Tricuspid annular plane systolic excursion (TAPSE) and strain were consistently associated with mortality. The most consistent predictor of MACE was RV myocardial performance index (MPI) across studies.

CONCLUSION

Pre- and perioperative assessment of RV function using at least two quantitative echocardiographic parameters may offer prognostic information in patients undergoing cardiac surgery. Right ventricular FAC, TAPSE, strain, and RV MPI have been frequently studied; however, further research is needed to delineate the role of echocardiographic RV quantification for perioperative prognostication.

STUDY REGISTRATION

PROSPERO ( CRD42023387383 ); first submitted 23 December 2022.

Assessing right atrial size in patients with tricuspid regurgitation: importance of the right ventricular-focused view

AIMS

To assess the accuracy of measuring the right atrial volume (RAV) using two-dimensional echocardiography (2DE) in a right ventricular focused (RVF) view compared to the conventional apical four-chamber (4Ch) view in patients with secondary tricuspid regurgitation (STR). We also compared the clinical correlates of the measures obtained using different methods.

METHODS AND RESULTS

The accuracy of RAV measurements obtained between 2DE-4Ch and RVF views in 384 patients with STR were compared using three-dimensional echocardiography (3DE) as a reference. We used the analysis of variance to test the differences among RAVs obtained from the different 2DE and 3DE acquisitions and the receiving operating characteristics (ROC) curves to evaluate the association with the composite endpoint of hospitalization for heart failure or death. Compared to 3DE, RAV was significantly more underestimated when measurements were obtained from 4Ch rather than RVF (-24 vs. -14%, respectively, P < 0.001 for both). RAV underestimation in 4Ch and RVF view was relatively larger in lower grades of STR (-28 vs. -17% in mild, -23 vs. -14% in moderate, and -19 vs. -11% in severe STR, P = 0.001), and in the atrial compared to ventricular (-28 vs. -22%; P = 0.002) STR. RAV measured by 3DE and RVF showed the highest area under the curve (AUC = 0.67 for 3DE vs. 0.64 for RVF, P = 0.05), while 4Ch was significantly less related to the outcomes (AUC: 0.61, P = 0.021 vs. 3DE RAV).

CONCLUSION

In patients with STR, the use of RVF view improved the accuracy of 2DE RAV measurement as compared to the conventional 4Ch-derived measurements.

Right atrial reverse remodeling and risk of atrial arrhythmias after surgical pulmonary valve replacement

Background

Right atrial (RA) dysfunction and atrial arrhythmias are relatively common in adults with repaired tetralogy of Fallot. The purpose of this study was to determine whether RA function improved after surgical pulmonary valve replacement (PVR), and the association between postoperative RA reverse remodeling and late postoperative atrial arrhythmias.

Method

RA reverse remodeling (ΔRA reservoir strain based speckle tracking echocardiography) was calculated as: ([postoperative RA reservoir strain - preoperative RA reservoir strain]/preoperative RA reservoir strain)x100. Optimal RA reverse remodeling was defined as ΔRA reservoir strain >15%.

Results

Of 411 patients (age 36 ± 13 years), preoperative RA reservoir strain was 31 ± 13%, postoperative RA reserve remodeling was 13 ± 9%, and 171 (42%) had optimal RA reserve remodeling. Preoperative RA reservoir strain (β±SE 1.12 ± 0.09, p < 0.001) was associated with postoperative RA reverse remodeling on multivariable analysis. Preoperative RA reservoir strain ≥33% predicted optimal postoperative RA reverse remodeling (area under the curve 0.792).ΔRA reservoir strain was associated with postoperative atrial arrhythmias (HR 0.91, 95%CI 0.86-0.96, p = 0.004), on multivariable analysis. Compared to patients with preoperative RA reservoir strain <33% (n = 242, 59%), those with RA reservoir strain ≥33% (n = 169, 41%) had more robust RA reverse remodeling (ΔRA reverse remodeling 19 ± 11% versus 7 ± 10%, p < 0.001), and lower incidence of atrial arrhythmias (1.1% versus 2.9%, p = 0.003).

Conclusions

Preoperative RA reservoir strain was associated with RA reverse remodeling after PVR, and in turn, postoperative atrial arrhythmia. These results suggest that RA strain indices could be used to determine optimal timing for PVR in order to reduce the risk of atrial arrhythmia.

The role of galectin-3 in patients with permanent and paroxysmal Atrial Fibrillation and echocardiographic parameters of left atrial fibrosis

BACKGROUND

Biochemical markers and imaging tests have been used with the aim of stratifying the risk and detecting atrial fibrosis. Speckle-tracking echocardiography (STE) is used for the detection of atrial fibrosis and Gal-3 provides an important prognostic value. The objective of the study was to assess the association between atrial fibrosis markers and serum levels, genetic polymorphisms and genic expression of galectin-3.

METHODS

206 patients with permanent AF and 70 patients with paroxysmal AF were included in the study. Real time PCR (TaqMan) system was used to study SNPs rs4652 and 4644 of the gene LGALS3. Serum levels of Gal-3 were determined by ELISA and STE was performed to assess fibrosis.

RESULTS

Mean age of individuals with permanent AF was 66.56 ± 12 years. As for the echocardiography results, those patients showed an decrease in the following parameters peak atrial longitudinal strain (PALS) (p = 0.002) when compared to the same parameters from the paroxysmal AF group of patients. There was a correlation between serum levels of Gal-3 and PALS in the group of patients with permanent AF; the lower the levels of gal-3, the lower the LA strain (r = 0.24; p = 0.01).

CONCLUSIONS

Echocardiographic findings showed association with the groups, and with serum levels of Gal-3 in patients with permanent AF. The distribution of allelic and genotypic frequencies, and of the haplotypes of polymorphism LGALS3 rs4652 and rs4644 did not present statistical variation, which suggests that those SNPs are not associated with the AF clinical forms (permanent and paroxysmal).

Incremental Value of Right Atrial Strain Analysis to Predict Atrial Fibrillation Recurrence After Electrical Cardioversion

BACKGROUND

Although the assessment of left atrial (LA) mechanics has been reported to refine atrial fibrillation (AF) risk prediction, it doesn't completely predict AF recurrence. The potential added role of right atrial (RA) function in this setting is unknown. Accordingly, this study sought to evaluate the added value of RA longitudinal reservoir strain (RASr) for the prediction of AF recurrence after electrical cardioversion (ECV).

METHODS

We retrospectively studied 132 consecutive patients with persistent AF who underwent elective ECV. Complete two-dimensional and speckle-tracking echocardiography analyses of LA and RA size and function were obtained in all patients before ECV. The end point was AF recurrence.

RESULTS

During a 12-month follow-up, 63 patients (48%) showed AF recurrence. Both LASr and RASr were significantly lower in patients experiencing AF recurrence than in patients with persistent sinus rhythm (LASr, 10% ± 6% vs 13% ± 7%; RASr, 14% ± 10% vs 20% ± 9%, respectively; P < .001 for both). Right atrial longitudinal reservoir strain (area under the curve = 0.77; 95% CI, 0.69-0.84; P < .0001) was more strongly associated with the recurrence of AF after ECV than LASr (area under the curve = 0.69; 95% CI, 0.60-0.77; P < .0001). Kaplan-Meier curves showed that patients with both LASr ≤ 10% and RASr ≤ 15% had a significantly increased risk for AF recurrence (log-rank, P < .001). However, at multivariable Cox regression, RASr (hazard ratio, 3.26; 95% CI, 1.73-6.13; P < .001) was the only parameter independently associated with AF recurrence. Right atrial longitudinal reservoir strain was more strongly associated with the occurrence of AF relapse after ECV than LASr, and LA and RA volumes.

CONCLUSION

Right atrial longitudinal reservoir strain was independently and more strongly associated than LASr with AF recurrence after elective ECV. This study highlights the importance of assessing the functional remodeling of both the RA and LA in patients with persistent AF.

Echocardiographic evaluation of the right atrial size and function: Relevance for clinical practice

Right atrial (RA) structural and functional evaluations have recently emerged as powerful biomarkers for adverse events in various cardiovascular conditions. Quantitative analysis of the right atrium, usually performed with volume changes or speckle-tracking echocardiography (STE), has markedly changed our understanding of RA function and remodeling. Knowledge of reference echocardiographic values and measurement methods of RA volumes and myocardial function is a prerequisite to introduce RA quantitation in the clinical routine. This review describes the methodology, benefits and pitfalls of measuring RA size and function by echocardiography based on the current understanding of right atrial anatomy and physiological function and provides the current knowledge of right atrial function in related cardiac diseases.

Echocardiographic correlates of MRI imaging markers of cerebral small-vessel disease in patients with atrial-fibrillation-related ischemic stroke

Background and objectives

Atrial fibrillation (AF) has been linked to dementia risk, partly explained by cerebral small vessel disease (CSVD). Since AF and cardiovascular comorbidities were associated with cardiac dysfunction, we aimed to determine the association between echocardiographic parameters and neuroimaging markers of CSVD in patients with AF-related ischemic stroke.

Methods

This cross-sectional study enrolled patients with AF-related ischemic stroke from March 2013 to December 2019 who underwent transthoracic echocardiography and brain 3T MRI, including T1, T2, Flair, and SWI imaging sequences. We assessed the presence of lacunes and cerebellar microbleeds (CMBs), the severity of white matter hyperintensity (WMH) scored by the Fazekas scale (0-6), and the severity of enlarged perivascular spaces (EPVS) in basal ganglia (BG) and centrum semiovale (CSO) classified into three categories (0-10, 10-25, and >25). CSVD burden was rated on a 0-to-4 ordinal scale. Generalized linear regression analysis and post hoc comparisons with Bonferroni correction were performed to assess the association between various echocardiographic parameters and these lesions, adjusted for demographics and potential confounders.

Results

119 patients (68.38 ± 12.692 years; male 45.4 %) were included for analysis, of whom 55 (46.2%) had lacunes, 40 (33.6%) had CMBs, and median severity for WMH, BG-EPVS, CSO-EPVS, and CSVD burden were 2 (IQR: 1-3), 1 (IQR: 1-2), 1 (IQR: 0-1), and 1 (IQR: 1-2) respectively. In multivariable, fully adjusted models, left ventricular posterior wall thickness (LVPW) was associated with a higher risk of lacunes (RR 1.899, 95% CI: 1.342-2.686) and CSVD burden (RR = 2.081, 95%CI: 1.562-2.070). Right atrial diameter (RAD) was associated with greater CSO-EPVS (RR = 2.243, 95%CI: 1.234-4.075). No echocardiographic parameters were revealed to be associated with CMBs and WMH.

Conclusion

In patients with AF-related ischemic stroke, LVPW is associated with a higher risk of lacunes and CSVD burden, while RAD was associated with greater CSO-EPVS. Larger studies are required to determine these associations and to elucidate if these associations can help facilitate cognitive evaluation and brain MRI screening.

Strain Echocardiography to Predict Postoperative Atrial Fibrillation

Postoperative atrial fibrillation (POAF) complicates 15% to 40% of cardiovascular surgeries. Its incidence progressively increases with aging, reaching 50% in octogenarians. This arrhythmia is usually transient but it increases the risk of embolic stroke, prolonged hospital stay, and cardiovascular mortality. Though many pathophysiological mechanisms are known, POAF prediction is still a hot topic of discussion. Doppler echocardiogram and, lately, strain echocardiography have shown significant capacity to predict POAF. Alterations in oxidative stress, calcium handling, mitochondrial dysfunction, inflammation, fibrosis, and tissue aging are among the mechanisms that predispose patients to the perfect "atrial storm". Manifestations of these mechanisms have been related to enlarged atria and impaired function, which can be detected prior to surgery. Specific alterations in the atrial reservoir and pump function, as well as atrial dyssynchrony determined by echocardiographic atrial strain, can predict POAF and help to shed light on which patients could benefit from preventive therapy.

Normal Ranges of Right Atrial Strain and Strain Rate by Two-Dimensional Speckle-Tracking Echocardiography: A Systematic Review and Meta-Analysis

Background: Normal range values of right atrial (RA) phasic function markers are essential for the identification of normal and abnormal values, comparison with reference values, and the clinical meaning of obtained values. Accordingly, we aimed to define the normal range values of RA phasic function markers obtained by 2D speckle-tracking echocardiography through a meta-analysis and determine the main sources of heterogeneity among reported values. Methods: PUBMED, SCOPUS, and EMBASE databases were searched for the following keywords: "right atrial/right atrium" and "strain/speckle/deformation" and "echocardiography." Studies were selected that included a human healthy adult group without any cardiovascular diseases or risk factors and that were written in the English language. For the calculation of each marker of RA phasic functions, a random-effect model was used. Meta-regression was employed to define the major sources of variabilities among reported values. Results: Fifteen studies that included 2,469 healthy subjects were selected for analysis. The normal range values for RA strain and strain rate were 42.7% (95% CI, 39.4 to 45.9%) and 2.1 s^-1 (95% CI, 2.0 to 2.1 s^-1) during the reservoir phase, respectively, 23.6% (95% CI, 20.7 to 26.6%) and -1.9 s^-1 (95% CI, -2.2 to -1.7 s^-1) during the conduit phase, correspondingly, and 16.1% (95% CI, 13.6 to 18.6%) and -1.8 s^-1 (95% CI, -2.0 to -1.5 s^-1) during the contraction phase, respectively. The sources of heterogeneity for the normal range of these markers were the number of participants, the type of software, the method of global value calculation, the right ventricular fractional area change, the left ventricular (LV) ejection fraction, the RA volume index, sex, the heart rate, the diastolic blood pressure, the body mass index, and the body surface area. Conclusions: Using 2D speckle-tracking echocardiography, we defined normal values for RA phasic function markers and identified the sources of heterogeneity as demographic, anthropometric, hemodynamic, and echocardiography factors. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021236578, identifier: CRD42021236578.

Standardization of normal values for cardiac chamber size in echocardiography

Echocardiography is used worldwide to evaluate cardiac size and function. To determine what values are abnormal, it is essential to establish normal reference values for echocardiography. The current guidelines for chamber quantification specify normative values for cardiac chambers and recommend that gender and body size be taken into account. However, these normative data were established using databases for which a variety of measurement methods were used and the majority of subjects consisted of Whites in Europe and the United States. However, several regional studies from other countries suggest that cardiac size varies globally. To overcome these limitations, the Normal Reference Ranges for Echocardiography study and the World Alliance of Societies of Echocardiography Normal Values study have recently been conducted to examine similarities and differences in cardiac chamber size and to establish normal reference values while taking worldwide diversity into account. The results from these studies have demonstrated that standardization of normal reference values for cardiac size is important. This review article aims to summarize the current status of normative echocardiographic values for cardiac chamber size.

Role of pre-operative transthoracic echocardiography in predicting post-operative atrial fibrillation after cardiac surgery: a systematic review of the literature and meta-analysis

AIMS

This systematic review and meta-analysis aims to evaluate the role of pre-operative transthoracic echocardiography in predicting post-operative atrial fibrillation (POAF) after cardiac surgery.

METHODS AND RESULTS

Electronic databases were searched for studies reporting on pre-operative echocardiographic predictors of POAF in PubMed, Cochrane library, and Embase. A meta-analysis of echocardiographic predictors of POAF that were identified by at least five different publications was performed. Forty-three publications were included in this systematic review. Echocardiographic predictors for POAF included surrogate parameters for total atrial conduction time (TACT), structural cardiac changes, and functional disturbances. Meta-analysis showed that prolonged pre-operative PA-TDI interval [5 studies, Cohen's d = 1.4, 95% confidence interval (CI) 0.9-1.9], increased left atrial volume indexed for body surface area (LAVI) (23 studies, Cohen's d = 0.8, 95% CI 0.6-1.0), and reduced peak atrial longitudinal strain (PALS) (5 studies, Cohen's d = 1.4, 95% CI 1.0-1.8), were associated with POAF incidence. Left atrial volume indexed for body surface was the most important predicting factor in patients without a history of AF. These parameters remained important predictors of POAF in heterogeneous populations with variable age and comorbidities such as coronary artery disease and valvular disease.

CONCLUSION

This meta-analysis shows that increased TACT, increased LAVI, and reduced PALS are valuable parameters for predicting POAF in the early post-operative phase in a large variety of patients.

Atrial Dyssynchrony Measured by Strain Echocardiography as a Marker of Proarrhythmic Remodeling and Oxidative Stress in Cardiac Surgery Patients

Aging leads to structural and electrophysiological changes that increase the risk of postoperative atrial arrhythmias; however, noninvasive preoperative markers of atrial proarrhythmic conditions are still needed. This study is aimed at assessing whether interatrial dyssynchrony determined using two-dimensional speckle tracking echocardiography relates to proarrhythmic structural and functional remodeling. A cohort of 45 patients in sinus rhythm referred for cardiac surgery was evaluated by echocardiography and surface electrocardiogram the day before the intervention. Transmembrane potential, connexin, and potassium channel distribution, inflammatory, and nitrooxidative markers were measured from right atrial tissue obtained from patients. A difference greater than 40 milliseconds between right and left atrial free wall contraction confirmed the presence of interatrial dyssynchrony in 21 patients. No difference in relation with age, previous diseases, and 2-dimensional echocardiographic findings as well as average values of global longitudinal right and left atrial strain were found between synchronic and dyssynchronic patients. Postoperative atrial fibrillation incidence increased from 8.3% in the synchronic group to 33.3% in the dyssynchronic ones. P wave duration showed no difference between groups. Action potentials from dyssynchronous patients decreased in amplitude, maximal rate of depolarization, and hyperpolarized. Duration at 30% of repolarization increased, being markedly shorter at 90% of repolarization. Only the dyssynchronous group showed early and delayed afterdepolarizations. Atrial tissue of dyssynchronous patients displayed lateralization of connexin 40 and increased connexin 43 expression and accumulation of tumor necrosis factor-α in the intercalated disc. Tumor necrosis factor-α did not colocalize, however, with lateralized connexin 40. Nitroxidative marks and KATP channels increased perivascularly and in myocytes. Our results demonstrate that, as compared to a traditional surface electrocardiogram, the novel noninvasive echocardiographic evaluation of interatrial dyssynchrony provides a better identification of nonaged-related proarrhythmic atrial remodeling with increased susceptibility to postoperative atrial fibrillation.

Higher Incidence of Atrial Fibrillation in Left Ventricular-to-Right Atrial Shunt Patients

Background: The possible association between atrial fibrillation (AF) and left ventricular-to-right atrial shunt (LVRAS) has never been reported yet. The present study investigated the incidence of AF in LVRAS. Methods: This was a retrospective study of consecutive patients undergoing echocardiography at a single tertiary center. Clinical data, laboratory results and echocardiography parameters such as right atrial area (RAA), right ventricular end diastolic diameter (RVDD) and left atrial diameter (LAD) were compared between LVRAS group and non-LVRAS patients, and between AF and non-AF patients. Propensity score matching was performed to decrease the effect of confounders. Logistic regression analysis and mediation analysis were used to estimate the relationship between LVRAS and AF. Results: A total of 3,436 patients were included, and the incidence of LVRAS was 1.16% (n = 40). The LVRAS group had significantly larger RAA, RVDD and LAD compared with non-LVRAS group. Those who suffered from AF showed larger RAA, RVDD and LAD compared with those who maintained sinus rhythm. Multivariable logistic regression showed that gender (OR: 0.608), age (OR: 1.048), LAD (OR: 1.111), mean pulmonary artery blood pressure (mPAP, OR: 1.023), TR (OR: 2.309) and LVRAS (OR: 12.217) were significant factors for AF. RAA could partially mediate the relationship between LVRAS and AF according to the result of mediation analysis. Conclusions: Our study suggested that LVRAS, TR, LAD, mPAP, age and male were risk factors for AF. RA enlargement might underlie mechanism in the higher incidence of AF in LVRAS patients. These findings should be confirmed in larger prospective studies.

Normal Values of Right Atrial Size and Function According to Age, Sex, and Ethnicity: Results of the World Alliance Societies of Echocardiography Study

BACKGROUND

The World Alliance Societies of Echocardiography study is a multicenter, international, prospective, cross-sectional study whose aims were to evaluate healthy adult individuals to establish age- and sex-normative values of echocardiographic parameters and to determine whether differences exist among people from different countries and of different ethnicities. The present report focuses on two-dimensional (2D) and three-dimensional (3D) right atrial (RA) size and function.

METHODS

Transthoracic 2D and 3D echocardiographic images were obtained in 2,008 healthy adult individuals evenly distributed among subgroups according to sex (1,033 men, 975 women) and age 18 to 40 years (n = 854), 41 to 65 years (n = 653), and >65 years (n = 501). For ethnicity, 34.9% were white, 41.6% Asian, and 9.7% black. Images were analyzed in a core laboratory according to current American Society of Echocardiography/European Association of Cardiovascular Imaging guidelines. RA measurements included 2D dimensions, 2D and 3D RA volumes (RAVs) indexed to body surface area (BSA), emptying fraction (EmF), and global longitudinal strain, including total/reservoir, passive/conduit, and active/contractile phases. Differences among age and sex categories and among countries were also examined.

RESULTS

RAVs were larger in men (even after BSA indexing), while 3D total EmF and global longitudinal strain magnitudes were higher in women. For both sexes, there were no significant age-related differences in 2D RAV measurements, but 3D RAV values differed minimally with age, remaining significant after BSA indexing. RA total EmF and reservoir strain and passive EmF and conduit strain magnitude were lower in older groups for both sexes. Interestingly, whereas RA active EmF increased with age, contractile strain magnitude decreased. Considerable geographic variations were identified: Asians of both sexes had significantly lower BSA than non-Asians, and their 2D and 3D end-systolic RAVs were significantly smaller even after BSA indexing. Of note, 2D end-systolic RAVs in this group were considerably lower than normal values provided in the current guidelines.

CONCLUSIONS

There is significant sex, age, and geographic variability in normal RA size and function parameters. Current guideline-recommended normal ranges for RA size and function parameters should be adjusted geographically on the basis of the results of this study.

Altered atrial cytosolic calcium handling contributes to the development of postoperative atrial fibrillation

Aims 

Atrial fibrillation (AF) is a commonly occurring arrhythmia after cardiac surgery (postoperative AF, poAF) and is associated with poorer outcomes. Considering that reduced atrial contractile function is a predictor of poAF and that Ca²⁺ plays an important role in both excitation–contraction coupling and atrial arrhythmogenesis, this study aims to test whether alterations of intracellular Ca²⁺ handling contribute to impaired atrial contractility and to the arrhythmogenic substrate predisposing patients to poAF.

Methods and results 

Right atrial appendages were obtained from patients in sinus rhythm undergoing open-heart surgery. Cardiomyocytes were investigated by simultaneous measurement of [Ca²⁺]_i and action potentials (APs, patch-clamp). Patients were followed-up for 6 days to identify those with and without poAF. Speckle-tracking analysis of preoperative echocardiography revealed reduced left atrial contraction strain in poAF patients. At the time of surgery, cellular Ca²⁺ transients (CaTs) and the sarcoplasmic reticulum (SR) Ca²⁺ content were smaller in the poAF group. CaT decay was slower in poAF, but the decay of caffeine-induced Ca²⁺ transients was unaltered, suggesting preserved sodium-calcium exchanger function. In agreement, western blots revealed reduced SERCA2a expression in poAF patients but unaltered phospholamban expression/phosphorylation. Computational modelling indicated that reduced SERCA activity promotes occurrence of CaT and AP alternans. Indeed, alternans of CaT and AP occurred more often and at lower stimulation frequencies in atrial myocytes from poAF patients. Resting membrane potential and AP duration were comparable between both groups at various pacing frequencies (0.25–8 Hz).

Conclusions 

Biochemical, functional, and modelling data implicate reduced SERCA-mediated Ca²⁺ reuptake into the SR as a major contributor to impaired preoperative atrial contractile function and to the pre-existing arrhythmogenic substrate in patients developing poAF.

Biatrial enlargement as a predictor for reablation of atrial fibrillation

Purpose: We aimed to determine whether biatrial enlargement could predict reablation of atrial fibrillation after first ablation. Methods: 519 consecutive patients with drug resistant atrial fibrillation [paroxysmal AF (PAF) 361, non-PAF 158] who underwent catheter ablation in Capital Medical University Xuanwu hospital between 2009 and 2014 were enrolled. Biatrial enlargement (BAE) was diagnosed according to trans-thoracic echocardiography (TTE). Ablation strategies included complete pulmonary vein isolation (PVI) in all patients and additional linear ablation across mitral isthmus, left atrium roof, left atrium bottom and tricuspid isthmus, or electrical cardioversion on the cases that AF could not be terminated by PVI. Anti-arrhythmic drugs or cardioversion were used to control the recurred atrial arrhythmia in patients with recurrence of atrial fibrillation after ablation. Reablation was advised when the drugs were resistant or that patient could not tolerate. Risk factors for reablation were analyzed. Results: After 33.11±21.45months, 170 patients recurred atrial arrhythmia, and reablation were applied in 117 patients. Multivariate Cox regression analysis demonstrated that that biatrial enlargement (BAE, HR 1.755, 95%CI 1.153-2.670, P=0.009) was an independent predictor for reablation and was associated with reablation (Log rank P=0.007). Conclusion: Biatrial enlargement is an independent risk predictor for the reablation in atrial fibrillation patients after first ablation.