Paroxysmal Atrial Fibrillation Subjects Research Articles

Low voltage area as a predictor of recurrence after a single pulmonary vein isolation procedure: results of the WAVE-MAP AF study

Abstract Background/Introduction Pulmonary vein isolation (PVI) is a recommended approach for atrial fibrillation (AF) ablation procedures. Substrate modification beyond PVI has mixed results but identifying and ablating low voltage zones and ablating those targets in addition to PVI may be beneficial. Electroanatomic mapping is critical to identify subjects that may require further substrate modification. Low voltage area may be predictive of optimal treatment approach. Purpose This was a prospective, multicenter, interventional study of a high-density grid-style mapping catheter (HD Grid) to characterize left atrial low voltage substrate during sinus rhythm (SR) and AF and identify associations with 12 month recurrence rates after a single de novo radiofrequency (RF) ablation using a PVI only approach. Methods This study (NCT03882021) enrolled 300 subjects at 18 centers in Europe and Israel. Subjects underwent de novo RF ablation for paroxysmal AF (PAF) (N=113), early persistent AF (PsAF; AF sustained 7 days to 3 months) (N=86) or non-early PsAF (AF sustained >3 months to 12 months) (N=101). High density voltage maps were collected with HD Grid. Two pre-ablation maps, in SR and AF, were created for each subject (N=196) followed by PVI only ablation. Low voltage area (using cutoffs of 0.1 mV to 1.5 mV) was investigated in SR and AF. Follow up visits were at 3, 6 and 12 months post-ablation, with a 24-hour Holter monitor at 12 months. A Cox proportional hazards model was used to identify associations between mapping data and 12 month AF/atrial flutter (AFL)/atrial tachycardia (AT) recurrence after a single PVI procedure. Results At 12 months, 75.5% of subjects were free from AF/AFL/AT recurrence. On average, PsAF subjects had more low voltage area than PAF subjects in SR and AF. However, while univariate analysis found no correlation between recurrence and PAF or PsAF diagnosis (p=0.1261), those with recurrence had a significantly larger percent left atrial low voltage area under 0.5 mV with simultaneous orthogonal bipole wave configuration (HDW) in both AF (p=0.0011) and SR (p=0.0210) than those without recurrence. Using HDW, low voltage area (identified as <0.5 mV) greater than 28% of the left atrium in SR (HR: 4.82, 95% CI: 2.08–11.18, p=0.0003) and greater than 72% in AF (HR: 5.66, 95% CI: 2.34–13.69, p=0.0001) were associated with a higher risk of AF/AFL/AT recurrence at one year. Conclusion(s) Using a standard cutoff of 0.5 mV, a larger percent low voltage area was associated with increased risk of recurrence in both SR and AF. Future analyses will explore optimal low voltage cutoffs and thresholds predictive of recurrence that may necessitate additional substrate modification beyond PVI. Funding Acknowledgement Type of funding sources: Private company. Main funding source(s): Abbott

Lesion Index-guided workflow for the treatment of paroxysmal atrial fibrillation is safe and effective - Final results from the LSI Workflow Study.

Pulmonary vein isolation (PVI) ablation is a standard therapy for paroxysmal atrial fibrillation (PAF). Lesion Index (LSI) is a metric to guide radiofrequency (RF) ablation using the TactiCath Ablation Catheter, Sensor Enabled with the EnSite Cardiac Mapping System (Abbott). This study (NCT-03906461) was designed to capture best practices using LSI-guided catheter ablation to treat PAF subjects in a real-world setting. This prospective single-arm observational study enrolled 143 PAF subjects in the United States, Europe, and Japan undergoing de novo PVI with RF ablation. PVI lesions were assigned to 10 anatomically defined segments. Mean LSIs achieved for all lesions were analyzed. Follow-up was conducted between 3-6 months and 12 months after the procedure. Pulmonary veins were isolated in all subjects. The mean achieved LSI was 4.9, with lower values in Europe (4.4) and Japan (4.5) than the United States (5.5). First-pass success, defined as no gaps requiring touch-up ablation after 20 minutes post isolation, was achieved in 76.2% of subjects. Use of high LSI (≥5) resulted in shorter procedure, RF, and fluoroscopy times and fewer touch-up ablations compared to low LSI (<5). At 12 months, 99.3% of subjects were free from procedure- or device-related serious adverse events and 95.7% (112/117) (35.0% on antiarrhythmic drugs) were free from recurrence and/or a repeat ablation procedure for atrial fibrillation / atrial flutter / atrial tachycardia. LSI-guided ablation strategies proved safe and effective despite differences in LSI workflows. Use of high LSI values resulted in shorter procedure, RF, and fluoroscopy times and fewer touch-up ablations compared to low LSI.

Detecting paroxysmal atrial fibrillation from normal sinus rhythm in equine athletes using Symmetric Projection Attractor Reconstruction and machine learning

BackgroundAtrial fibrillation (AF) is a common cardiac arrhythmia in both human and equine populations. It is associated with adverse outcomes in humans and decreased athletic performance in both populations. Paroxysmal atrial fibrillation (PAF) presents with intermittent, self-terminating AF episodes, and is difficult to diagnose once sinus rhythm resumes.ObjectiveWe aimed to detect PAF subjects from normal sinus rhythm equine electrocardiograms (ECGs) using the Symmetric Projection Attractor Reconstruction (SPAR) method to encapsulate the waveform morphology and variability as the basis of a machine learning classification.MethodsWe obtained ECG signals from 139 active equine athletes (120 control, 19 with a PAF diagnosis). The SPAR method was applied to 9 short (20-second) ECG strips for each subject. An optimal SPAR feature set was determined by forward feature selection for input to a machine learning model ensemble of 3 different classifiers (k-nearest neighbors, linear support vector machine, and radial basis function kernel support vector machine). Imbalanced data were handled by upsampling the minority (PAF) class. A final subject classification was made by taking a majority vote over results from the 9 ECG strips.ResultsOur final cross-validated classification for a subject gave an accuracy of 89.0%, sensitivity of 94.8%, specificity of 87.1%, and receiver operating characteristic area under the curve of 0.98, taking PAF as the positive class.ConclusionThe SPAR method and machine learning generated a final model with high sensitivity, suggesting that PAF can be discriminated from short equine ECG strips. This preliminary study indicated that SPAR analysis of human ECG could support patient monitoring, risk stratification, and clinical decision-making.

Left Ventricular Flow Distribution as a Novel Flow Biomarker in Atrial Fibrillation.

Introduction: Four-dimensional (4-D) flow cardiac magnetic resonance imaging can be used to elegantly describe the hemodynamic efficiency of left ventricular (LV) flow throughout the cardiac cycle. Patients with nonvalvular paroxysmal atrial fibrillation (PAF) may have occult LV disease. Flow distribution analysis, based on 4-D flow, may unmask the presence of LV disease by assessing flow components: direct flow, retained flow, delayed ejection, and residual volume. This study aimed to identify LV hemodynamic inefficiencies in patients with PAF and normal systolic function. We hypothesized that the fraction of direct flow to the total end-diastolic volume would be reduced in patients with PAF compared with controls. Methods: We used 4-D LV flow component analysis to compare hemodynamics in 30 healthy controls and 50 PAF patients in sinus rhythm. Results: PAF subjects and healthy controls had similar LV mass, volume, and ejection fraction. Direct flow was lower in the PAF group than in the controls (44.5 ± 11.2% vs. 50.0 ± 12.2%, p = 0.042) while delayed ejection was higher in the PAF group (21.6 ± 5.6% vs. 18.6 ± 5.7%, p = 0.022). Conclusion: PAF patients demonstrated a relative reduction in direct flow and elevation in delayed ejection.

Acute safety and performance outcomes from the inspIRE trial using a novel pulsed field ablation system for the treatment of paroxysmal atrial fibrillation

Abstract Background/Introduction The inspIRE clinical trial was designed to assess the safety and efficacy of a fully integrated biphasic pulsed field ablation (PFA) system comprised of a multi-channel generator, variable decapolar irrigated loop circular catheter, and mapping system (Figure A) for the treatment of paroxysmal atrial fibrillation (PAF). Purpose Using this novel PFA system in a multicentre clinical trial, we present the initial feasibility of electrical pulmonary vein isolation (PVI), procedural performance, and acute safety results. Methods inspIRE is a prospective, non-randomized, multi-centre study, planned to enrol up to 550 patients. PVI is performed with the novel, variable loop circular catheter, compatible mapping system and generator. Acute procedural effectiveness (entrance block in all clinically targeted PVs post adenosine/isoproterenol challenge) and the incidence of primary adverse events (PAEs) were assessed. PAEs are defined as the occurrence of cardiac tamponade/perforation, myocardial infarction, stroke/cerebrovascular accident, thromboembolism, transient ischemic attack, permanent phrenic nerve paralysis, pulmonary edema, pericarditis, and any major vascular access complications within 7 days of the ablation procedure. Additionally, any incidence of procedure or device related death, atrio-esophageal fistula, or PV stenosis (related to the ablation procedure or study catheter) within the 12M follow-up period is classified as a PAE. Results A total of 35 PAF subjects (age 59.7±10.7 years, 54.3% male) were treated across 5 European sites by 6 operators. Acute procedural success was achieved in 100% of study subjects (Figure B) with zero incidence of PAEs. Mean total procedure time was 82.9±19.9 minutes with 27.0±11.9 minutes of PFA from first to last application. Average fluoroscopy use was 10.6±6.8 minutes and LA dwell time was 45.6±15.3 minutes. Conclusion Initial results of the inspIRE trial demonstrate the acute safety and effectiveness of the new integrated IRE circular catheter, mapping system and generator for PVI in PAF patients. Funding Acknowledgement Type of funding sources: Other. Main funding source(s): inspIRE is a company-sponsored study funded by Biosense Webster, Inc. Figure 1. (A) PFA System; (B) PVI Voltage Map

B-PO05-073 THE FASTR-AF TRIAL: ASSESSING THE DIAMOND TIP TEMPERATURE-CONTROLLED RADIOFREQUENCY ABLATION CATHETER TO TREAT PATIENTS WITH ATRIAL FIBRILLATION

Catheter ablation (CA) technology evolves as practitioners look to improve treatment options for atrial fibrillation (AF). A novel diamond tip, irrigated, radiofrequency (RF) ablation system accurately measures tip-tissue temperature in real-time and modulates power to maintain a target therapeutic tissue temperature. Recently, the DiamondTemp Ablation (DTA) system demonstrated strong outcomes against a contact force-sensing RF ablation system in a paroxysmal AF (PAF) population. However, no data pertaining to persistent AF (PsAF) has been reported in literature. This study sought to characterize the performance of the DTA system for the treatment of patients with drug-refractory PAF and PsAF with the second-generation RF DTA generator. DIAMOND FASTR-AF (NCT03626649) was a prospective, single-arm, multicenter European trial. Primary effectiveness endpoint was freedom from atrial arrhythmia recurrence following a 90-day blanking period through 12 months. Primary safety endpoint was a composite of serious adverse events. In total, 60 subjects (34 PAF and 26 PsAF) underwent CA with the DTA system at three centers. Patient demographics were consistent with contemporary AF studies (male 71.7%, age 63.9 ± 10.2 yrs, AF history 3.1 ± 3.9 yrs, LA size 4.4 ± 0.8 cm). The PAF cohort showed marked procedural efficiencies, as compared to PsAF, in total procedure time (76.9 ± 21.7 min vs 108.9 ± 33.6 min, p<0.001, respectively), total RF time (10.4 ± 3.5 min vs 20.4 ± 8.0 min, p<0.001), and number of RF applications (62.1 ± 25.3 vs 109.5 ± 45.5, p<0.001). Pulmonary vein isolation only was performed in 82% of PAF and 23% of PsAF subjects. Additional left-sided lesions were performed in 69% of PsAF subjects (vs 6% of PAF subjects). Safety event rate in the PAF and PsAF groups were 5.9% (2/34) and 11.5% (3/26), respectively. Freedom from recurrence was observed in 67.6% (23/34) of PAF and 61.5% (16/26) of PsAF subjects. The DiamondTemp Ablation system demonstrated long-term safety and effectiveness through 12 months post-ablation for patients with PAF or PsAF. Procedures were demonstrated to be highly efficient, with shorter time and fewer applications seen in PAF procedures.

Ganoderma lucidum Polysaccharide Peptide Reduce Inflammation and Oxidative Stress in Patient with Atrial Fibrillation

BACKGROUND: Atrial fibrillation (AF) could be triggered by inflammation and oxidative stress. Ganoderma lucidum has an active substance in the form of β-glucan that can reduce inflammatory process and oxidative stress in rats. The objective of this study was to evaluate the effect of Ganoderma lucidum polysaccharide peptide (GLPP) in paroxysmal AF subjects with parameters of anti-inflammatory antioxidant, electrocardiography and health-related quality of life (HRQoL).METHODS: A randomized closed-label clinical trial with pre- and post-test design was conducted. After AF subjects selection, the subjects were randomized, interviewed and veni-punctured to isolate blood plasma. AF Subjects were then treated with placebo or GLPP for 90 days. Post-test blood plasma was collected on the following day after the 90th day. Then anti-inflammatory and antioxidant parameters were measured. After that, echocardiographic and HRQoL assessments were performed.RESULTS: A total of 38 subjects, 11 males and 27 females, completed the study with no significant changes in diets, physical activities, or medications. Comparing to control, the 90-days GLPP-treated subject characteristics were significant difference in systolic blood pressure, heart rate, malondialdehyde, high-sensitivity C-reactive protein, tumor necrosis factor-a, interleukin (IL)-1b, IL-6, primary (P)-wave dispersion, P-max, physical functioning, limitation to physical health, energy/fatigue, pain, and physical limitation.CONCLUSION: GLPP has several potential effects in AF subjects, including anti-inflammatory, antioxidant, and atrial remodelling, so that HRQoL of AF subjects could be improved. Hence, GLPP could suggested as a potential supplementing agent for AF management.KEYWORDS: atrial fibrillation, Ganoderma lucidum, inflammation, antioxidant, atrial remodelling, quality of life

Comparison of apolipoprotein-A1 levels between paroxysmal atrial fibrillation patients and healthy subjects.

Introduction: Studies found that the inflammation plays a key role in the pathogenesis of paroxysmal atrial fibrillation (PAF). It is well-known that apolipoprotein-A1 (Apo-A1) demonstrates antiinflammatory and anti-oxidant properties in a healthy physiological system. In the present study, we aimed to determine whether there is any difference of Apo-A1 levels in patients with PAF and healthy subjects. Methods: In this prospective cohort study, we enrolled a total of 35 PAF patients and 34 comparable healthy participants. Apo-A1 levels were measured from each subject using an immunophelometric method. All enrolled subjects were followed-up for one year during the study period. Results: Serum high-sensitivity C-reactive protein (hs-CRP) levels were statistically higher in PAF patients compared to healthy subjects (1.54±1.99 vs. 1.06±2.01, P = 0.016, respectively). Of note, patients with PAF had lower Apo-A1 levels (1.84±0.74 vs. 2.55±0.44, P = 0.001, respectively). There was no statistical difference between the groups in terms of apolipoprotein-B levels (1.08±0.36 vs. 0.99±0.38, P = 0.339, respectively). We did not find any correlation between Apo-A1 levels and PAF attacks in the study. Conclusion: The main finding of this study was that Apo-A1 levels were significantly lower in PAF patients compared to healthy participants. Based on our results, we considered that Apo-A1 may have a key role in the pathogenesis of PAF.

Magnetocardiography detects left atrial dysfunction in paroxysmal atrial fibrillation

Magnetocardiography (MCG) is a non-invasive technique and to characterize the magnetic field, a pseudo-current conversion was used. The role of MCG in detecting left atrial (LA) dysfunction in patients with paroxysmal atrial fibrillation (PAF) is unknown. The aim of this study was to evaluate LA function using MCG in patients with PAF and healthy subjects, to identify possible indices to diagnose PAF. We enrolled a total of 70 subjects including 26 healthy volunteers (group 1) and 22 marathon runners (group 2) who did not exhibit any cardiac abnormalities, and 22 patients with PAF (group 3) which was documented by electrocardiography (ECG). Spatiotemporal activation graph (STAG) in base-apex and left-right direction was reconstructed. The maximum value of LA pseudo-current under rest and peak exercise were measured between the end of the P wave and beginning of the Q wave. LA pseudo-current increase at peak exercise in PAF patients was significantly lower than in healthy volunteers and marathon runners (0.4±0.3 pT in group 3 vs. 0.8±0.3 pT in group 1 vs. 1.1±0.5 pT in group 2, p < 0.001). PAF patients had less pseudo-current increase in STAG at peak exercise than healthy volunteers and marathon runners (46% of 26 PAF patients, 81% of 22 healthy subjects vs. 81% of 22 marathon runners, p = 0.002). Sensitivity, specificity, and the area under the receiver-operator characteristics curve of LA pseudo-current increase at peak exercise for differentiating PAF patients from healthy subjects were 77%, 92%, and 0.896. MCG can provide important non-invasive information for detecting LA dysfunction in PAF patients. Therefore, MCG may help in differentiating PAF patients from healthy subjects.

Abstract 25: Abnormalities within Normal Sinus Rhythm

Trained cardiologists detect atrial fibrillation by visual interpretation of certain segments of electrocardiogram (EKG) lines known as the QRS complex. Similarly, available EKG-software also evaluates anomalies in the signals from the EKG-leads that produce the traces/lines in order to flag for atrial fibrillation. We and others have previously shown that machine learning methods successfully identify patients with paroxysmal atrial fibrillation (PAF) based on their EKG during normal sinus rhythm. In this work, we go beyond the earlier black-box approaches and identify specific patterns in the QRS complex of a normal sinus rhythm that are associated with atrial fibrillation. We implemented frequent pattern mining on discretized waveform raw EKG data to determine patterns that are specific to patients with PAF based on 1-minute Lead 1 EKG recordings sampled at 128 Hz from 25 patients with PAF and 50 healthy subjects from a Physionet data repository. We discretized the down-sampled (16 Hz) EKG traces with seven symbols corresponding to various degrees of local variability within the traces and selected from the existing unique 1,306 4-symbol patterns the 850 patterns occurring at least 5 times (to mitigate sparsity related problems). The resulting 75x850 pattern frequency matrix represented the frequency of each pattern within each of the 75 patients and PAF subjects were distinguished based on a binary Least Absolute Shrinkage and Selection Operator regression with 5-fold cross validation that selected 50 of the patterns (AUC = 0.95; 95% C.I. 0.88-1.00; 94% specificity, 88% sensitivity). These 50 patterns are candidates to elicit the “fingerprint” of PAF within normal sinus rhythm: e.g., one of the selected patterns in Figure 1 was observed in 76% of PAF patients while it was present only in 30% of healthy patients. Our study is a proof of concept that machine learning and artificial intelligence techniques are not restricted to black-box approaches and can be used to derive interpretable insights that could lead to novel biomarkers associated with certain health conditions.

Association of serum nesfatin-1 concentrations with atrial fibrillation

Nesfatin-1, a newly discovered adipokine, inhibits inflammatory response. Inflammation is involved in the mechanism of atrial fibrillation (AF). We aim to determine the association between serum nesfatin-1 concentrations and AF. A population of 200 patients with AF and 108 patients without AF were enrolled in this study. These patients were divided into three subgroups of paroxysmal AF, persistent AF, and permanent AF. Serum nesfatin-1 concentrations were lower in AF patients than in controls. Logistic regression analysis showed that serum nesfatin-1 concentrations were inversely associated with AF. Serum nesfatin-1 concentrations in permanent AF patients decreased compared with those in persistent and paroxysmal AF groups. In addition, persistent AF patients showed reduced serum nesfatin-1 concentrations compared with paroxysmal AF subjects. Serum nesfatin-1 concentrations were negatively correlated with left atrial diameter. In conclusion, serum nesfatin-1 concentrations were inversely correlated with AF development.

Association of serum chemerin concentrations with the presence of atrial fibrillation.

Objective Chemerin, a newly discovered adipokine, is correlated with hypertension, diabetes and coronary heart disease. The aim of this study is to investigate the association of serum chemerin concentrations with the presence of atrial fibrillation. Methods Serum chemerin concentrations were determined in 256 patients with atrial fibrillation and 146 healthy subjects. Atrial fibrillation patients were then divided into paroxysmal, persistent and permanent atrial fibrillation. Results Serum chemerin concentrations were significantly higher in atrial fibrillation patients compared with healthy controls. In subgroup studies, patients with permanent atrial fibrillation had higher serum chemerin concentrations than those with persistent and paroxysmal atrial fibrillation. Furthermore, significant higher serum chemerin concentrations were observed in persistent atrial fibrillation patients compared with paroxysmal atrial fibrillation subjects. Serum chemerin concentrations were associated with the presence of atrial fibrillation after logistic regression analysis. Pearson correlation analysis revealed a positive relation of serum chemerin concentrations with body mass index, systolic blood pressure, diastolic blood pressure, triglycerides, low-density lipoprotein cholesterol, blood urea nitrogen, creatinine, C-reactive protein and left atrial diameter. Conclusion Serum chemerin concentrations are associated with the presence of atrial fibrillation and atrial remodelling.

Development of an alert system for subjects with paroxysmal atrial fibrillation

BackgroundKnowledge of the onset of atrial fibrillation (AF) episodes in patients with paroxysmal atrial fibrillation (PAF) will enable them to better manage this condition. Current advances in mobile technology allow RR interval data to be obtained in real time. An analysis technique using RR interval data is presented with a view to alert a subject before a PAF episode. MethodThe method is based on a time series of standard deviation and 0.99 quantile values of the spectral entropy, constructed from RR data. The RR data are taken from three time periods. The first time period has no occurrences of AF for 45min to either side of the time period. The second time period just precedes an AF attack. Both of these are of thirty minutes duration. The third time period of approximately 5min follows the second, and is when AF occurs. ResultsTwenty-two PAF subjects were studied and in all cases there was a steady increase in the values of these indices as the onset of the AF attack approached. ConclusionThis method of analysis of RR interval data shows potential use to alert a PAF subject before the onset of an AF episode.

Epicardial Fat in Atrial Fibrillation and Heart Failure

Obesity is a well-known risk factor for atrial fibrillation (AF) and heart failure (HF). Epicardial fat, the true visceral fat depot of the heart, has been associated with changes in both cardiac function and morphology. In this study, we evaluated whether ultrasound-measured epicardial fat thickness is related to AF and HF. A cross-sectional study was performed in 84 consecutive subjects with clinical and ECG-documented history of permanent (AF) or paroxysmal AF (PAF) who underwent echocardiographic epicardial fat thickness measurement. Sixty-four subjects had AF and 20 showed PAF. AF subjects had higher prevalence of heart failure (HF), defined by ejection fraction (EF)<50%, (p<0.01). Subjects with AF had higher epicardial fat thickness than PAF subjects (4.8±2.5 vs. 3.5±2.4 mm, p<0.05). As subjects were stratified by HF, epicardial fat thickness was lower (4.4±2.2 vs. 5.4±2.3 mm, p<0.05) in those with HF as compared to subjects without HF. This study showed for the first time that echocardiographic epicardial fat thickness is significantly higher in subjects with chronic AF when compared to those with PAF. It is plausible that permanent AF is related to long-term influence of epicardial fat. Epicardial fat reduction in HF subjects may reflect the overall fat mass reduction, commonly observed in these patients. It is also possible to hypothesize that epicardial fat pad may incur in fibrotic changes during chronic cardiac failure.

Total and Interatrial Epicardial Adipose Tissues Are Independently Associated With Left Atrial Remodeling in Patients With Atrial Fibrillation

As epicardial adipose tissue (EAT) is a metabolically active visceral fat, potential interaction between EAT and myocardium is strongly suggested. The aims of this study were to determine whether the amount and regional distribution of EAT are related to the chronicity of atrial fibrillation (AF) and left atrial (LA) remodeling. This study consisted of 40 subjects with paroxysmal AF (PAF) and 40 with persistent AF (PeAF). Eighty subjects with no history of AF were enrolled as controls. Total volume of EAT (EAT(total)), regional thickness of EAT, and LA volume (LAV) were measured by multislice computed tomography. In the AF group, blood samples were drawn from coronary sinus for analysis of inflammatory cytokines including adiponectin. Compared with controls, AF subjects had larger LAV, EAT(total), and the thicknesses of periatrial EAT including interatrial septum (IAS). However, the thicknesses of periventricular EAT were not different between the groups. The PeAF subjects had larger LAV, EAT(total), and periatrial EAT thicknesses, higher levels of inflammatory cytokines, and lower level of adiponectin than did the PAF subjects. Adiponection level was significantly associated with EAT(total) and IAS thickness. Multivariate analysis revealed that EAT(total) (P = 0.004) and IAS thickness (P = 0.016) were independently associated with LAV. EAT(total) and thickness of periatrial EAT were significantly larger in AF subjects compared to those of the matched controls and were closely related to the chronicity of AF. Moreover, EAT(total) and IAS thickness were independently associated with LAV in subjects with AF.

Stroke risk might be specifically correlated with the burden of paroxysmal atrial fibrillation

Dear Sir, Patients with paroxysmal atrial fibrillation (PAF) appear to be at risk of adverse cardiovascular events irrespective of whether they have been specifically identified as having this subtype of atrial fibrillation (AF) [1] or whether they are masquerading as members of a rhythm-controlled subtype of AF [2, 3]. In the context of rhythm control of AF, approximately 81% of rhythm-controlled subjects relapse into AF (including PAF) during 12-month follow-up [4], and the true prevalence of PAF in the aforementioned rhythm-controlled subjects [2, 3] might well have been of this order of magnitude. What any analysis of PAF-related cardiovascular risk should take into account is that the burden of PAF might not be uniform either in subjects specifically identified as having PAF [1] or in unidentified PAF subjects within the subgroup designated as being under rhythm control [2, 3]. Refinements in the quantification of PAF burden [5] not utilized in the present study [1] or in other studies [2, 3] might help to define whether or not there is a correlation between PAF burden and cardiovascular risk. Such a correlation is a plausible one given the observation that AF occurrences longer than 1 day are the ones which appear to be independently associated with embolic events [6]. No conflict of interest to disclosure.

Volumetric Cine CMR to Quantify Atrial Structure and Function in Patients with Atrial Dysrhythmias

To implement a cardiac magnetic resonance (CMR)-based protocol to define atrial structure and function in individuals with paroxysmal atrial fibrillation (PAF), heritable cardiac conduction and myocardial disease with atrial dysrhtyhmias (HCCMD), and healthy controls. Fifteen controls, 20 PAF, and 12 HCCMD subjects underwent CMR examination including: multislice short-axis cine, multislice horizontal long-axis cine, and gadolinium-enhanced coronal plane magnetic resonance angiography (MRA) for pulmonary vein analysis. We also assessed for ventricular myopathy with delayed myocardial enhancement (DME) acquisitions. Right and left ventricular measurements did not differ among the three groups. Seven heritable atrial dysrhythmia subjects and no control or PAF subjects demonstrated midmyocardial fibrosis of the basal interventricular septum by DME. Left atrial (LA) volume at the onset of atrial systole and minimal LA volume were significantly higher in PAF subjects compared to controls (p < 0.05 for both), LA percent emptying was significantly lower in PAF subjects (p < 0.01), and RA percent emptying was significantly lower in PAF subjects compared to controls (p < 0.01), though these differences were not significant when controlling for heart rate, age and gender. There was no significant difference in right atrial (RA) volumes among study groups. Atrial volumes and function did not differ significantly between heritable atrial dysrhtyhmia subjects and controls. PAF subjects had greater frequency of a right middle pulmonary vein (RMPV) than controls (6/20 vs. 3/15) that did not reach statistical significance. CMR can quantify atrial structure and function in patients with PAF compared to controls. This protocol could not detect abnormalities in atrial function in early affected patients with heritable cardiomyopathy and atrial premature beats.

Action potential duration restitution kinetics in human atrial fibrillation

ObjectivesWe undertook this study to determine whether human atrial fibrillation (AF) relates to steeply sloped action potential duration restitution (APDR) kinetics and whether the spatial nonuniformity of APDR promotes persistence of AF. BackgroundA steeply sloped APDR curve is known to be an important determinant of the induction of more complex action potential duration (APD) dynamics and fibrillation. MethodsPatients with chronic atrial fibrillation (CAF) (n = 18), paroxysmal atrial fibrillation (PAF) (n = 14) and normal control subjects (n = 9) were studied. The monophasic action potential duration at 90% repolarization (APD90) and the effective refractory period (ERP) were measured at six sites in the right atrium. After AF was electrically converted, APDR was assessed by delivering a single extrastimulus after a train of stimuli at a cycle length of 600 ms (S1S2) at six different sites of the right atrium, as well as rapid pacing at cycle lengths that induced APD alternans. ResultsThe APD90and ERP in patients with CAF were shorter than those in patients with PAF and control subjects (p < 0.05); however, the dispersions of APD90and ERP in each group were similar. The maximal slopes of APDR by S1S2and rapid pacing in patients with CAF (1.2 ± 0.4 and 1.7 ± 0.2) and PAF (1.1 ± 0.4 and 1.3 ± 0.4) were higher than those in control subjects (0.5 ± 0.3 and 0.8 ± 0.2, respectively; p < 0.01). The maximal slope obtained by S1S2did not differ from that obtained by rapid pacing in any group. The inter-regional difference of the maximal slope in patients with CAF (1.6 ± 0.4, p < 0.05) was greater than that in patients with PAF (1.2 ± 0.3, p = NS vs. control) and control subjects (0.4 ± 0.2). ConclusionsAtrial fibrillation was related to steeply sloped (>1) APDR kinetics. The spatial dispersion of APDR in patients with chronic AF was greater than that of patients with paroxysmal AF and control subjects, indicating that the heterogeneity of APDR of the atrium plays an important role in the persistence of AF.