Left atrial appendage "stunning" after electrical cardioversion of atrial flutter: an attenuated response compared with atrial fibrillation as the mechanism for lower susceptibility to thromboembolic events

The Risk of Left Atrial Appendage Thrombus in Patients With Atrial Flutter Versus Atrial Fibrillation

Objective

Patients with atrial fibrillation (AF) are at increased risk of thromboembolic events originating mainly from left atrial appendage thrombus (LAAT). Patients with atrial flutter (AFL) are treated with anticoagulation based on the same criteria as patients with AF. However, whether patients with AFL have similar thromboembolic risk as AF is unclear. In the current study we aimed to estimate the prevalence of LAAT in patients with AFL undergoing trans-esophageal echocardiography (TEE).

Methods/results

We included 438 patients (404 with AF and 34 with AFL) scheduled for TEE to rule out LAAT before cardioversion (patients who reported no or inadequate anticoagulation before cardioversion). Demographic and echocardiographic data were compared between patients with and without LAAT. Despite a similar CHA2DS2-VASC score (3.8 ± 1.3 vs 3.4 ± 1.5 in the AF and AFL groups, respectively, P = .09), LAAT was documented in 12 (2.8%) in the AF group and in no patient in the AFL group (P < .0001).

Conclusion

Based on our results and previous studies, it seems reasonable to re-evaluate the need for oral anticoagulation in specific populations with AFL such as those with solitary AFL (without a history of AF episodes) undergoing successful ablation and in those with low CHA2DS2-VASC score.

2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

The "2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation" provides recommendations to guide clinicians in the treatment of patients with atrial fibrillation.

METHODS

A comprehensive literature search was conducted from May 12, 2022, to November 3, 2022, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through November 2022, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate.

STRUCTURE

Atrial fibrillation is the most sustained common arrhythmia, and its incidence and prevalence are increasing in the United States and globally. Recommendations from the "2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation" and the "2019 AHA/ACC/HRS Focused Update of the 2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation" have been updated with new evidence to guide clinicians. In addition, new recommendations addressing atrial fibrillation and thromboembolic risk assessment, anticoagulation, left atrial appendage occlusion, atrial fibrillation catheter or surgical ablation, and risk factor modification and atrial fibrillation prevention have been developed.

2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

The "2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Patients With Atrial Fibrillation" provides recommendations to guide clinicians in the treatment of patients with atrial fibrillation.

METHODS

A comprehensive literature search was conducted from May 12, 2022, to November 3, 2022, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through November 2022, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate.

STRUCTURE

Atrial fibrillation is the most sustained common arrhythmia, and its incidence and prevalence are increasing in the United States and globally. Recommendations from the "2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation" and the "2019 AHA/ACC/HRS Focused Update of the 2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation" have been updated with new evidence to guide clinicians. In addition, new recommendations addressing atrial fibrillation and thromboembolic risk assessment, anticoagulation, left atrial appendage occlusion, atrial fibrillation catheter or surgical ablation, and risk factor modification and atrial fibrillation prevention have been developed.

Transition from transesophageal echocardiography to cardiac computed tomography for the evaluation of left atrial appendage thrombus prior to atrial fibrillation ablation and incidence of cerebrovascular events during the COVID-19 pandemic

BACKGROUND

Transesophageal echocardiography (TEE) is variably performed before atrial fibrillation (AF) ablation to evaluate left atrial appendage (LAA) thrombus. We describe our experience with transitioning to the pre-ablation cardiac computed tomography (CT) approach for the assessment of LAA thrombus during the COVID-19 pandemic.

METHODS

We studied consecutive patients undergoing AF ablation at our center. The study cohort was divided into pre- versus post-COVID groups. The pre-COVID cohort included ablations performed during the 1 year before the COVID-19 pandemic; pre-ablation TEE was used routinely to evaluate LAA thrombus in high-risk patients. Post-COVID cohort included ablations performed during the 1 year after the COVID-19 pandemic; pre-ablation CT was performed in all patients, with TEE performed only in patients with LAA thrombus by CT imaging. The demographics, clinical history, imaging, and ablation characteristics, and peri-procedural cerebrovascular events (CVEs) were recorded.

RESULTS

A total of 637 patients (pre-COVID n = 424, post-COVID n = 213) were studied. The mean age was 65.6 ± 10.1 years in the total cohort, and the majority were men. There was a significant increase in pre-ablation CT imaging from pre- to post-COVID cohort (74.8% vs. 93.9%, p ≤ .01), with a significant reduction in TEEs (34.6% vs. 3.7%, p ≤ .01). One patient in the post-COVID cohort developed CVE following negative pre-ablation CT. However, the incidence of peri-procedural CVE between both cohorts remained statistically unchanged (0% vs. 0.4%, p = .33).

CONCLUSION

Implementation of pre-ablation CT-only imaging strategy with selective use of TEE for LAA thrombus evaluation is not associated with increased CVE risk during the COVID-19 pandemic.

Vorhofflimmern und NOAK-Therapie: Benötigen wir eine transösophageale Echokardiografie vor Kardioversion?

Vorhofflimmern ist ein häufiger Grund für einen Schlaganfall. Insbesondere Patienten ohne adäquate Antikoagulation haben ein erhöhtes Risiko für thromboembolische Ereignisse (ca. 5–7%). Es liegt eine Assoziation zwischen Kardioversionen und embolischen Ereignissen vor. Durch eine orale Antikoagulation (OAK) mit Nicht-Vitamin-K-Antagonisten (NOAK) kann dieses Risiko auf unter 1% reduziert werden. Es gibt 2 unterschiedliche Kardioversionsstrategien. Zum einen kann eine Kardioversion nach 3-wöchiger effektiver Antikoagulation ohne weitere Bildgebung durchgeführt werden. Zum anderen kann nach Ausschluss einer intrakardialen Thrombenbildung durch eine TEE umgehend sicher kardiovertiert werden. Bei Vorhofflimmern sollte nach der Kardioversion eine effektive Antikoagulation für mindestens 4 Wochen erfolgen, unabhängig vom CHA2DS2-VASc-Score. Eine Bildgebung mittels TEE ist notwendig, wenn die Dauer einer effektiven Antikoagulation <3 Wochen ist, Unsicherheiten bezüglich der regelmäßigen und lückenlosen Medikamenteneinnahme bestehen oder ein hohes Risiko für linksatriale Thromben besteht.

The impact of basic atrial rhythm during catheter ablation of atrial fibrillation on clinical outcomes: Lessons from the German Ablation Registry

BACKGROUND

The impact of basic atrial rhythm (sinus rhythm [SR] vs. atrial fibrillation [AF]) during AF ablation on efficacy and safety is unknown.

METHODS

About 3375 patients from the German Ablation Registry undergoing first-time AF ablation were divided according to the type of AF and the basic atrial rhythm during the ablation procedure: paroxysmal AF (PAF) and SR [group Ia], PAF and AF [group Ib]), persistent AF and SR (IIa), and persistent AF and AF (IIb).

RESULTS

Patients in SR (n = 2312 [67%]) underwent cryoballoon ablation more often (Ia vs. Ib p = .002 and IIa vs. IIb p = .010, whereas in patients in AF (n = 1063 [33%]) radiofrequency (RF)-based ablation (Ia vs. Ib p = .006 and IIa vs. IIb p = .014) including left and/or right atrial substrate modification was more frequently performed. Depending on the basic rhythm there was no difference regarding arrhythmia recurrence during long-term follow-up. For patients suffering from persistent AF acute procedure-related complications were more often documented when ablated in AF (9.1% vs. 4.6%, p = .012). which was mainly driven by the higher occurrence of pericardial effusion/tamponade. For patients suffering from persistent AF, favorable results were found regarding 366-day Kaplan-Meier estimates of the incidence of MACCE (death, myocardial infarction, and stroke; p = .011) and the composite endpoint of death, myocardial infarction, stroke, and major bleeding (p = .006), when ablated in SR.

CONCLUSION

Basic atrial rhythm at the time of AF ablation did not affect long-term rhythm outcome. For patients suffering from persistent AF a more favorable acute and long-term safety profile was observed when ablated in SR.

Difference in the prevalence of intracardiac thrombus on the first presentation of atrial fibrillation versus flutter in the pediatric and congenital heart disease population

INTRODUCTION

Guidelines recommend trans-esophageal echocardiography (TEE) for patients with atrial fibrillation (AF) or atrial flutter (AFL) for >48 h, due to risk of intracardiac thrombus formation. With growing evidence that AFL in adults with structurally normal hearts has less thrombogenic potential compared to AF, and the need for TEE questioned, we compared prevalence of intracardiac thrombus detected by TEE in pediatric and congenital heart disease (CHD) patients presenting in AF and AFL.

METHODS/RESULTS

Single-center, cross-sectional analysis for unique first-time presentations of patients for either AF, AFL, or intra-atrial reentrant tachycardia (IART) between 2000 and 2019. Patients were categorized by presenting arrhythmia (AF vs. AFL/IART), with the exclusion of other forms of atrial tachycardia, hemodynamic instability, chronic anti-coagulation before TEE, and presentation for a reason other than TEE examination for thrombus. A total of 201 patients had TEE with co-diagnosis of AF or AFL. Of these, 105 patients (29 AF, 76 AFL) met inclusion criteria, with no difference in age between AF (median 24.9 years; IQR 18.6-38.3 years) and AFL/IART (23.3 years; 15.4-38.4 years). The prevalence of thrombus in the entire cohort was 9.5%, with no difference between AF (13.8%) and AFL groups (7.9%), p = .46. Patients with thrombus demonstrated no difference in age, systemic ventricular function, cardiac complexity, or CHADS2/CHA2DS2VASc score at presentation.

CONCLUSIONS

The risk for intracardiac thrombus is high in the pediatric and CHD population, with no apparent distinguishing factors to warrant a change in the recommendations for TEE, with all levels of cardiac complexity being at risk for clot.

Predictors of left atrial appendage stunning after electrical cardioversion in patients with atrial fibrillation

The transient left atrial appendage (LAA) dysfunction after electrical cardioversion (CV), which is called as LAA-stunning, was found to be an important etiology of thrombus formation. The aim of the present study was to investigate the risk factors of LAA-stunning. This study included 134 patients who underwent catheter ablation for non-paroxysmal, non-valvular, and symptomatic atrial fibrillation (AF). Internal-CV was performed, and LAA emptying fraction (LAA-EF) was assessed using LAA-angiogram before and just after CV. LAA-stunning (defined as 10% reduction of LAA-EF after CV) was observed in 45/134 patients (34%). Patients in LAA-stunning group had longer duration of AF prior to CV, higher brain natriuretic peptide (BNP), higher prevalence of patients taking calcium blocker, larger left atrial (LA) diameter, elevated E wave, and larger LA volume than those in non LAA-stunning group. Multivariate analysis showed that longer duration of AF prior to CV (p = 0.015, OR 1.033 for 1 month extend, 95% CI 1.006-1.073) and elevated BNP (p = 0.038, OR 1.041 for each 10 pg/mL increase, 95% CI 1.001-1.009) were associated with LAA-stunning. In addition, all patients were divided into four groups based on the combination between duration of AF prior to CV and BNP; group 1 (low BNP/short-lasting AF), group 2 (high BNP/short-lasting AF), group 3 (low BNP/long-lasting AF), and group 4 (high BNP/long-lasting AF). The rate of LAA-stunning was the highest in the group 4 (55.6%). Elevated BNP and long duration of AF were associated with LAA stunning after electrical cardioversion.

Atrial electromechanical delay assessment in early phase after catheter ablation for patients with atrial fibrillation

BACKGROUND

Variation of atrial electromechanical delay (AED) in early phase after catheter ablation in patients with atrial fibrillation (AF) is lacking.

METHODS

Fifty-five consecutive patients restored sinus rhythm after ablation was included. Echocardiography was performed at 4 h, 1 day, and 3 days after radiofrequency catheter ablation, and AED was measured simultaneously by echocardiography with pulse Doppler imaging and pulse wave tissue Doppler imaging.

RESULTS

AED parameters were significantly longer in the nonparoxysmal atrial fibrillation (NPAF) group than in the paroxysmal atrial fibrillation (PAF) group at each checking point after ablation (P < 0.05). Compared with other checking points, AED parameters were significantly longer 4 h postablation in the NPAF group, while no significant difference was found between different checking points in the PAF group. AED-leap, representing the variation of AED in NPAF patients, was significantly positively correlated with the duration of NPAF (r = 0.5291, P = 0.0113).

CONCLUSIONS

Compared with PAF, NPAF patients have a longer AED postablation, and an abrupt decrease in the initial-h postablation. Such phenomenon gives rise to the different clinical features of PAF and NPAF, and could guide different assessment and treatment strategies for different types of AF.

Adjunctive left anterior line ablation induced left atrial dysfunction and dyssynchrony in atrial fibrillation ablation

We evaluated the effects of adjunctive left anterior line (LAL) ablation on LA dyssynchrony and function using real-time three-dimensional echocardiography (3DE) in connection with thromboembolic complications and tachyarrhythmia recurrence in patients with persistent atrial fibrillation (AF). We randomly and prospectively assigned consecutive persistent AF patients to the LAL (n = 52, 65 ± 7 years) and control groups (n = 50, 64 ± 10 years). In the LAL group, extensive encircling pulmonary vein isolation (EEPVI), roof line ablation, and LAL ablation regardless of the extent of the low-voltage area (LVA) were performed. The control group underwent EEPVI and roof line ablation. After ablation, 3DE demonstrated LA dyssynchrony in 23 (46%) and 4 patients (8%, P < 0.001) of the LAL and control groups, respectively. Baseline LA LVAs were relatively small in most patients and there were no significant differences in extent of LVA between control and LAL groups or between patients with and without dyssynchrony. During the follow-up periods (771 ± 121 days), patients with LA dyssynchrony in the LAL group did not show significant differences in symptomatic thromboembolic events (0%) and atrial tachyarrhythmia recurrence (39%) from patients without LA dyssynchrony in the LAL (0% and 30%) and control groups (0% and 32%, respectively). LA ejection fraction and active emptying fraction were lower by 9% on average in the LAL group than in the control group (P < 0.0001). Similarly, in the LAL group, LA ejection fraction, active emptying fraction, and expansion index were significantly lower by approximately 7%, 8%, and 15%, respectively, in LA with dyssynchrony than those in LA without dyssynchrony. In conclusion, LA dyssynchrony and LA hypofunction were induced by LAL ablation in patients with persistent AF and relatively mild LVA. LAL ablation with or without LA dyssynchrony is thought not to affect thromboembolic complications or atrial tachyarrhythmia recurrence.

Atorvastatin can ameliorate left atrial stunning induced by radiofrequency ablation for atrial fibrillation

The objective of this study was to study the functional changes of the left atrium after radiofrequency ablation treatment for atrial fibrillation and the therapeutic effect of atorvastatin. Fifty-eight patients undergoing radiofrequency ablation for atrial fibrillation were randomly divided into non-atorvastatin group and atorvastatin group. Patients in the atorvastatin group were treated with atorvastatin 20 mg p.o. per night in addition to the conventional treatment of atrial fibrillation; patients in the non-atorvastatin group received conventional treatment of atrial fibrillation only. Echocardiography was performed before radiofrequency ablation operation and 1 week, 2 weeks, 3 weeks, and 4 weeks after operation. Two-dimensional ultrasound speckle tracking imaging system was used to measure the structural indexes of the left atrium. Results indicated that there was no significant change for indexes representing the structural status of the left atrium within a month after radiofrequency ablation (P > 0.05); however, there were significant changes for indexes representing the functional status of the left atrium. There were also significant changes in indexes reflecting left atrial strain status: the S and SRs of atorvastatin group were higher than those of non-atorvastatin group (P < 0.05). In summary, atorvastatin could improve left atrial function and shorten the duration of atrial stunning after radiofrequency ablation of atrial fibrillation.

Atrial Flutter, Typical and Atypical: A Review

Clinical electrophysiology has made the traditional classification of rapid atrial rhythms into flutter and tachycardia of little clinical use. Electrophysiological studies have defined multiple mechanisms of tachycardia, both re-entrant and focal, with varying ECG morphologies and rates, authenticated by the results of catheter ablation of the focal triggers or critical isthmuses of re-entry circuits. In patients without a history of heart disease, cardiac surgery or catheter ablation, typical flutter ECG remains predictive of a right atrial re-entry circuit dependent on the inferior vena cava-tricuspid isthmus that can be very effectively treated by ablation, although late incidence of atrial fibrillation remains a problem. Secondary prevention, based on the treatment of associated atrial fibrillation risk factors, is emerging as a therapeutic option. In patients subjected to cardiac surgery or catheter ablation for the treatment of atrial fibrillation or showing atypical ECG patterns, macro-re-entrant and focal tachycardia mechanisms can be very complex and electrophysiological studies are necessary to guide ablation treatment in poorly tolerated cases.

Do Different Atrial Flutter Types Carry the Same Thromboembolic Risk?

Thromboembolic risk of atrial flutter (AFl) types has not been elucidated sufficiently in previous reports. The authors classified the patients according to surface electrocardiogram and electrophysiologic characteristics as those with typical AFl (37 patients, 78.4% male, mean age 59.8 ±9.5 years) and atypical AFl (13 patients, 69.2% male, mean age 60.9 ±6.9 years) and compared them regarding some clinical, echocardiographic, and hematologic parameters. An age- and gender-matched control group composed of 20 individuals without any organic heart disease in sinus rhythm was chosen (80% male, mean age 60.3 ±7.9 years). Clinical features such as age, gender, organic heart disease, hypertension, diabetes mellitus, AFl duration, and the prevalence of paroxysmal atrial fibrillation were similar in both AFl groups. Echocardiographic parameters such as left ventricular ejection fraction, left atrial (LA) diameter, LA spontaneous echo contrast, and LA appendage emptying velocities were similar in both AFl groups. Fibrinogen, fibrin D-dimer, and thrombin-antithrombin III levels reflecting coagulation system activity were found to be increased in the patients with atypical AFl when compared with those with typical AFl and the control group (p<0.001). In Pearson’s correlation analysis, significant correlation between these hematologic markers and clinical and echocardiographic parameters were not found (p>0.05). The coagulation system activity was found to be increased in patients with atypical AFl. Thus, anticoagulation due to the increased thromboembolic risk should be considered in patients with atypical AFl.

A Stunning Left Atrial Appendage Thrombus

BACKGROUND

Left atrial appendage thrombus formation is a known major complication of atrial fibrillation and atrial flutter which increases the risk of embolism and stroke. This risk of thrombosis is greatly increased with a lack of anticoagulation. After conversion to a normal sinus rhythm in these arrhythmias, the risk of thrombus formation in the left atrium persists through a phenomenon termed atrial myocardial stunning.

CASE

We present the case of a patient who previously underwent successful pulmonary vein isolation and was found to be in typical isthmus-dependent atrial flutter with a questionable recurrence of atrial fibrillation. The decision was made to return for atrial flutter ablation and for evaluation of prior pulmonary vein isolation. Initially, a transesophageal echocardiogram showed a normal ejection fraction, biatrial enlargement and no left atrial appendage thrombus. Ablation of the cavotricuspid isthmus was successfully accomplished with documented bidirectional block. A transesophageal echocardiogram probe was still in place prior to planned transseptal puncture for the evaluation of pulmonary veins. A large thrombus was now observed filling the left atrial appendage. Conclusion and Objective: Atrial stunning is a transient atrial contractile dysfunction that occurs whether sinus rhythm is restored spontaneously, electrically, pharmacologically or by ablation. We know after conversion that there is higher propensity to increased spontaneous echogenic contrast and decreased velocities; however, we do not have documented knowledge of exactly how soon after the conversion to a sinus rhythm a thrombus may be seen. We demonstrate a case of acute left atrial appendage thrombus formation immediately following the successful ablation of isthmus-dependent atrial flutter. Our report validates the belief that strategies of not interrupting anticoagulation prior to the conversion of these arrhythmias should be implemented.

Executive Summary: European Heart Rhythm Association Consensus Document on the Management of Supraventricular Arrhythmias: Endorsed by Heart Rhythm Society (HRS), Asia-Pacific Heart Rhythm Society (APHRS), and Sociedad Latinoamericana de Estimulación Cardiaca y Electrofisiologia (SOLAECE)

This paper is an executive summary of the full European Heart Rhythm Association (EHRA) consensus document on the management of supraventricular arrhythmias, published in Europace. It summarises developments in the field and provides recommendations for patient management, with particular emphasis on new advances since the previous European Society of Cardiology guidelines. The EHRA consensus document is available to read in full at http://europace.oxfordjournals.org.

The left atrial appendage: anatomy, function, and noninvasive evaluation

The left atrial appendage (LAA) is a finger-like extension originating from the main body of the left atrium. Atrial fibrillation (AF) is the most common clinically important cardiac arrhythmia, occurring in approximately 0.4% to 1% of the general population and increasing with age to >8% in those >80 years of age. In the presence of AF thrombus, formation often occurs within the LAA because of reduced contractility and stasis; thus, attention should be given to the LAA when evaluating and assessing patients with AF to determine the risk for cardioembolic complications. It is clinically important to understand LAA anatomy and function. It is also critical to choose the optimal imaging techniques to identify or exclude LAA thrombi in the setting of AF, before cardioversion, and with current and emerging transcatheter therapies, which include mitral balloon valvuloplasty, pulmonary vein isolation, MitraClip (Abbott Laboratories, Abbott Park, Illinois) valve repair, and the implantation of LAA occlusion and exclusion devices. In this review, we present the current data regarding LAA anatomy, LAA function, and LAA imaging using the currently available noninvasive imaging modalities.

Prevalence of auricular thrombosis before atrial flutter cardioversion: a 17-year transoesophageal echocardiographic study

AIMS

Prevalence of left appendage thrombosis ranges from 6 to 18% in persistent atrial fibrillation (AF). Few and low sample size studies have assessed left and right atrial thrombosis in persistent atrial flutter (AFL) and a wide variety of frequencies, from 1 to 21%, has been reported. The aim of this study was to evaluate the prevalence of atrial appendage thrombosis in a large population of patients undergoing transoesophageal echocardiography (TEE)-guided cardioversion (CV) for recent AFL onset and compare it with AF.

METHODS AND RESULTS

From 1999 to September 2014, we collected data of 1081 patients to CV: 877 affected by AF (81.1%) and 204 by AFL (18.9%). The presence of auricular thrombosis was evaluated by TEE in AF or AFL persisting for more than 48 h. The presence of appendage thrombosis, Doppler emptying velocities, and severe spontaneous echo contrast (SEC) was studied. The overall prevalence of atrial thrombosis was 9.62% (104/1081). Frequency of atrial thrombosis in AFL patients was 6.4% (13/204) vs. 10.5% among AF (92/877), P = 0.074. Comparing the two appendages, frequency of left atrial appendage thrombosis was in AFL 5.9% (12/204) vs. 9.9% (87/877) in the AF group, P = 0.07. Right atrial appendage thrombosis was present in 0.5% (1/204) in the AFL group vs. 0.8% (7/877) in the AF group, P = 0.64. Moderate to severe SEC (3+/4+) was present in 28% of AFL patients (57/204) vs. 35% of AF patients (307/877), P = 0.05.

CONCLUSION

Auricular thrombosis is not an infrequent finding in AFL before CV. Our study suggests the use of TEE screening in AFL, as well as in AF, when patients arrive to clinical attention after more than 48 h from arrhythmia onset.

Prevalence of intracardiac thrombi under phenprocoumon, direct oral anticoagulants (dabigatran and rivaroxaban), and bridging therapy in patients with atrial fibrillation and flutter

Direct oral anticoagulants (DOACs) are effective for stroke prevention in nonvalvular atrial fibrillation (AF). Cardioversion (CV) is frequently performed in patients with AF or flutter. To further explore the safety profile of DOACs in the context of CV, we sought to assess the prevalence of intracardiac thrombi under DOAC therapy in comparison with treatment with vitamin K antagonists. A total of 672 transesophageal echocardiograms performed in 643 patients with a history of nonvalvular AF were analyzed. The median CHA2DS2-VASc score was 4. Cases were stratified according to anticoagulation with dabigatran (n = 79), rivaroxaban (n = 122), phenprocoumon (n = 180), or bridging therapy (n = 287). In a subgroup analysis, only patients receiving phenprocoumon with an international normalized ratio ≥2 on the day of the investigation or on DOAC therapy for ≥3 weeks were considered. The prevalence of intracardiac thrombi under phenprocoumon was significantly higher than under DOACs (phenprocoumon, 17.8%; all DOACs, 3.9%; dabigatran, 3.8%; rivaroxaban, 4.1%) and showed no significant difference to bridging therapy (12.5%). In patients with sufficient short-term anticoagulation, similar differences between DOAC and phenprocoumon groups were observed (phenprocoumon, 18.4%; all DOACs, 3.8%; dabigatran, 0%; rivaroxaban, 6.6%). The influence of anticoagulation medication on thrombus rates was confirmed after adjusting for baseline intergroup differences regarding left atrial size and CHA2DS2-VASc score. In conclusion, the prevalence of intracardiac thrombi was lower under DOAC therapy than under phenprocoumon in this high-risk patient cohort. Safety of CV during DOAC treatment requires further prospective evaluation.

Structural and Functional Remodeling of the Left Atrium: Clinical and Therapeutic Implications for Atrial Fibrillation

Atrial fibrillation (AF) is the most commonly encountered arrhythmia in clinical practice. Despite advances in our understanding of the pathophysiology of this complex arrhythmia, current therapeutic options remain suboptimal. This review aimed to delineate the atrial structural and functional remodeling leading to the perpetuation of AF. We explored the complex changes seen in the atria in various substrates for AF and the therapeutic options available to prevent these changes or for reverse remodeling. Here we also highlighted the emerging role of aggressive risk factor management aimed at the arrhythmogenic atrial substrate to prevent or retard AF progression.

High plasma human atrial natriuretic peptide and reduced transthoracic left atrial appendage wall-motion velocity are noninvasive surrogate markers for assessing thrombogenesis in patients with paroxysmal atrial fibrillation

BACKGROUND

The clinical relevance of examining human atrial natriuretic peptide (HANP) or left atrial appendage (LAA) wall-motion velocity during sinus rhythm in paroxysmal atrial fibrillation (AF) patients has not been clearly elucidated.

METHODS

The subjects were 38 patients with paroxysmal AF who underwent transesophageal and transthoracic echocardiography during sinus rhythm. The presence of spontaneous echocontrast (SEC) was examined with transesophageal echocardiography and LAA wall-motion velocity (LAAWV) was measured with transthoracic tissue Doppler echocardiography. Plasma HANP was measured within 3 hours after echocardiography.

RESULTS

Human atrial natriuretic peptide ranged from 12 to 106 pg/mL with an average of 43 ± 24 pg/mL and had a significant correlation with LAAWV (r = -0.57) or LAA flow velocity (r = -0.41). HANP was significantly higher in patients with SEC than in patients without SEC (64 ± 29 vs. 34 ± 15 pg/mL, P = 0.008) and LAAWV was significantly lower in patients with SEC than in patients without SEC (13 ± 5 vs. 20 ± 5 cm/sec, P = 0.002). HANP >44 pg/mL had a sensitivity of 73% and specificity of 89% for diagnosing SEC. SEC was more frequently observed (73%) in patients with HANP >44 pg/mL and/or LAAWV <10 cm/sec as compared with patients (11%) with normal HANP and LAA wall-motion velocity (P < 0.0001).

CONCLUSION

Higher plasma HANP and lower LAA wall-motion velocity may be noninvasive surrogate markers for assessing left atrial thrombogenesis during sinus rhythm in paroxysmal AF patients.

Dabigatran etexilate for thromboembolic prophylaxis in non-valvular atrial fibrillation: the RE-LY study and substudies with commentary

In 2010, dabigatran etexilate, a direct thrombin inhibitor, was the first new oral anticoagulant to be approved for thromboembolic prophylaxis in atrial fibrillation in over 50 years. Dabigatran, unlike warfarin, has a short half-life with a rapid onset of anticoagulant effect, does not require dose adjustment or monitoring, and does not interact with food. The RE-LY trial compared two doses of dabigatran (110 and 150 mg twice daily) with adjusted dose warfarin in patients with non-valvular atrial fibrillation and at least 1 stroke risk factor. Compared with warfarin, dabigatran 150 mg twice daily was superior in reducing the risk of stroke or systemic embolism and was associated with a similar rate of major bleeding, while dabigatran 110 mg twice daily was equally effective in reducing stroke or systemic embolism and was associated with less major bleeding. Despite these favorable results, there remains disagreement regarding the optimal dose and overall safety of dabigatran in certain patient populations including the elderly and those with renal dysfunction.

Effect of atrial fibrillation on atrial thrombogenesis in humans: impact of rate and rhythm

OBJECTIVES

We sought to assess the effect of atrial fibrillation (AF) on atrial thrombogenesis in humans by determining the impact of rate and rhythm.

BACKGROUND

Although AF is known to increase the risk of thromboembolic stroke from the left atrium (LA), the exact mechanisms remain poorly understood.

METHODS

We studied 55 patients with AF who underwent catheter ablation while in sinus rhythm; 20 patients were induced into AF, 20 patients were atrial paced at 150 beats/min, and 15 were control patients. Blood samples were taken from the LA, right atrium, and femoral vein at baseline and at 15 min in all 3 groups. Platelet activation (P-selectin) was measured by flow cytometry. Thrombin generation (thrombin-antithrombin [TAT] complex), endothelial dysfunction (asymmetric dimethylarginine [ADMA]), and platelet-derived inflammation (soluble CD40 ligand [sCD40L]) were measured using enzyme-linked immunosorbent assay.

RESULTS

Platelet activation increased significantly in both the AF (p < 0.001) and pacing (p < 0.05) groups, but decreased in control patients (p < 0.001). Thrombin generation increased specifically in the LA compared with the periphery in both the AF (p < 0.01) and pacing (p < 0.01) groups, but decreased in control patients (p < 0.001). With AF, ADMA (p < 0.01) and sCD40L (p < 0.001) levels increased significantly at all sites, but were unchanged with pacing (ADMA, p = 0.5; sCD40L, p = 0.8) or in control patients (ADMA, p = 0.6; sCD40L, p = 0.9).

CONCLUSIONS

Rapid atrial rates and AF in humans both result in increased platelet activation and thrombin generation. Prothrombotic activation occurs to a greater extent in the human LA compared with systemic circulation. AF additionally induces endothelial dysfunction and inflammation. These findings suggest that although rapid atrial rates increase the thrombogenic risk, AF may further potentiate this risk.

Interactions between cardiovascular and cerebrovascular disease

OPININION STATEMENT: All patients with ischemic stroke should undergo a comprehensive assessment of cardiovascular risk. Patients with carotid artery disease, symptoms of cerebral ischemia and high cardiovascular risk profiles should be considered for noninvasive testing for coronary artery disease (CAD). Routine testing for CAD before carotid endarterctomy is not recommended. Patients with coexisting coronary and carotid artery disease should be more aggressively treated for reducing their "very high" risk of cardiovascular events. In patients candidates to carotid revascularization, a preoperative coronary angiography and coronary revascularization are not recommended. Warfarin is recommended in all patients with moderate to high risk of stroke. Novel oral anticoagulants represent an attractive alternative to warfarin. However, their place in therapy in clinical practice is not yet established. Percutaneous closure of the left atrial appendage for stroke prophylaxis may be considered in selected patients with atrial fibrillation and contraindications for oral anticoagulant therapy. Warfarin is not indicated in patients with heart failure who are in sinus rhythm. Percutaneous closure of patent foramen does not seem to be superior to medical therapy for the prevention of recurrences in patients with cryptogenic stroke.

Omega-3 PUFAs and atrial fibrillation: have we made up our mind yet?

Atrial fibrillation (AF) is the most common type of arrhythmia in adults, accounting for about one third of total arrhythmia-related hospitalizations. AF impact on daily clinical practice is steadily rising, together with population aging and increased survival from underlying conditions closely associated with AF such as coronary heart disease and heart failure. Although antiarrhythmic therapy, oral anticoagulation, implanted device therapy, and ablation techniques are now all common and promptly available strategies in AF management, some of them are burdened by a low efficacy rate, while others are associated with increased proarrhythmic or hemorrhagic risk. Consequently, useful alternatives are being sought. Between those, polyunsaturated fatty acids (n-3 PUFAs) have risen from mere alternative to statins in dyslipidemia management to powerful and well-tolerated antiinflammatory, antithrombotic, and antiarrhythmogenic drugs. From the evidence collected through basic science studies, whether on in vivo myocytes, animal models, or surrogate end points in human, n-3 PUFAs seem to offer innumerable advantages. On the other hand, epidemiological and clinical trials failed to demonstrate a clear efficacy of n-3 PUFAs as antiarrhythmic drugs, although covered by an optimal safety profile. The aim of the present review is to summarize the most important evidences currently available on the role of n-3 PUFA in AF management and therapy.

Effect of Ramipril Therapy on Abnormal Left Atrial Appendage Function

This study investigated whether ramipril treatment has a beneficial effect on left atrial appendage (LAA) function in patients with systemic hypertension in sinus rhythm. Patients with untreated systemic hypertension and normal left ventricular systolic function in sinus rhythm ( n = 20; six males/14 females; age 35 – 69 years, mean ± SD 52.8 ± 8.9 years) were evaluated using transthoracic and transoesophageal echocardiography at baseline and after 6 months of treatment with 5 mg/day ramipril. Mean systolic and diastolic blood pressures decreased significantly after ramipril therapy. Baseline LAA emptying velocity was below the age-related reference value for this parameter, indicating abnormal LAA function. There were significant increases in the LAA filling and emptying velocities after ramipril treatment. It is concluded that the decrease in blood pressure and haemodynamic improvements brought about by ramipril therapy resulted in improved LAA function in hypertensive patients with normal left ventricular systolic function in sinus rhythm.

Digitalis does not improve left atrial mechanical dysfunction after successful electrical cardioversion of chronic atrial fibrillation

This study was designed to investigate whether administration of digitalis could improve mechanical function of left atrial appendage (LAA) and left atrium prospectively in patients with atrial stunning. Fifty-four consecutive patients in whom atrial stunning was observed immediately after cardioversion of chronic atrial fibrillation (AF) were randomized into digitalis or control group for 1 week following cardioversion. Transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) were performed prior to, immediately following, 1 day after and 1 week after cardioversion to measure transmitral flow velocity and LAA flow velocity. Electrical cardioversion of AF elicited significantly slower left atrial appendage peak emptying velocity (LAA-PEV) and peak filling velocity (LAA-PFV) immediately following cardioversion in both groups. 1 day post cardioversion, there were no significant differences in transmitral E wave, A wave, E/A ratio, LAA-PEV, LAA-PFV or left atrial appendage ejection fraction (LAA-EF) between digitalis and control groups. 1 week post cardioversion, no significant differences were found in transmitral E wave, A wave, E/A ratio, LAA-PEV, LAA-PFV or LAA-EF between the two groups. The occurrence rates of spontaneous echo contrast were not significantly different between digitalis and control groups one day and one week post cardioversion. In conclusion, digitalis did not improve left atrial and appendage mechanical dysfunction following cardioversion of chronic AF. Digitalis did not prevent the development of spontaneous echo contrast in left atrial chamber and appendage. This may be due to the fact that digitalis aggravates intracellular calcium overload induced by chronic AF and has a negative effect on ventricular rate.

Transient local injury current in right ventricular electrogram after implantable cardioverter-defibrillator shock predicts heart failure progression

OBJECTIVES

This study aimed to identify an early marker of functional impairment after an implantable cardioverter-defibrillator (ICD) shock as a predictor of heart failure progression.

BACKGROUND

The ICD population has substantial risk of death due to progressive pump failure.

METHODS

Near-field (NF) bipolar right ventricular (RV) electrograms (EGMs) during induced ventricular fibrillation (VF) and 10 s after rescue ICD shock were analyzed in 310 patients (mean age 59 +/- 14.5 years, 219 men [71%]) with structural heart disease, New York Heart Association functional class I to III, and implanted with a single- or dual-chamber Medtronic (Minneapolis, Minnesota) ICD for primary (245 patients, 79%) or secondary prevention of sudden cardiac arrest. A local injury current (LIC) on NF RV EGM was defined as a deviation of EGM potential > or =1 mV or > or =15% of the preceding R-wave peak-to-peak amplitude.

RESULTS

During mean follow-up of 29.3 +/- 15.0 months, the combined end point of death or hospitalization due to congestive heart failure (CHF) exacerbation was documented in 40 patients (12.9%, or 5.3% per person-year of follow-up). LIC was observed in 106 patients. In multivariate risk analysis, after adjustment for baseline prognostic factors (ejection fraction, history of atrial fibrillation, diabetes mellitus) and appropriate ICD shocks during follow-up, patients with observed LIC after induced VF rescue ICD shock at ICD implantation were more likely to die or to be hospitalized (hazard ratio: 2.69; 95% confidence interval: 1.41 to 5.14; p = 0.003).

CONCLUSIONS

Transient LIC on bipolar NF RV EGM after induced VF rescue ICD shock is associated with increased risk of CHF progression, future hospitalizations due to CHF exacerbation, and subsequent heart failure death.

Left atrial thrombus formation immediately after mitral valve replacement: a case report

Mechanical dysfunction from valve thrombosis is a dreaded complication of valve replacement surgery, usually presenting months to years after the procedure. Here we report acute deterioration of prosthetic valve function due to intraoperative obstruction by a thrombus.

Resolution of atrial thrombosis with heparin in a newborn with atrial flutter

Atrial thrombosis is a relatively rare event in children. We report a case of a newborn with AFI who after restoration of sinus rhythm, developed atrial thrombus on a prominent Chiari network floating between the right and left atrium through the patent foramen ovale. The thrombus was resolved following treatment with heparin without events.

CONCLUSION

Atrial stunning was proposed as a key mechanistic phenomenon because the thrombus occurred after the cardioversion of AFI to sinus rhythm. Heparin may be effective in the resolution of atrial thrombus within a few days.

TEE screening in Atrial flutter: A single-centre experience with retrospective validation of a new risk score for the presence of atrial thrombi

Transesophageal echocardiography (TEE) has been proposed as a screening tool to exclude the presence of atrial thrombi and left atrial spontaneous echocontrast before cardioverting persistent atrial flutter (AFl) and atrial fibrillation (AF). However in pure AFl a very low prevalence of atrial thrombi has been observed by many investigators: a confirmation of this finding would make TEE screening redundant. We review our database of patients with AFl who underwent TEE screening before cardioversion in the last 5 years. A new risk score for the presence of left atrial thrombus (AFLAT score) is here proposed, as a potential tool to avoid unnecessary TEE exams. Out of the 106 patients examined, in fourteen left atrial thrombi were diagnosed (13%). Only two cases belonged to the pure AFl subgroup (prevalence=3%), while twelve cases were detected in the subgroup of AFl patients with previous AF episodes (prevalence=32%, p<0.001). All of the fourteen patients with a positive TEE for thrombus were identified by a AFLAT score >2. The validation of this index in a larger and prospective setting would lead to a 85% reduction in unnecessary TEE exams in patients with pure AFl undergoing cardioversion.

Mitral annular velocity by Doppler tissue imaging for the evaluation of atrial stunning after cardioversion of atrial fibrillation

OBJECTIVE

Atrial and/or appendage stunning (AS) usually occur after successful cardioversion of atrial fibrillation (AF). Several parameters except mitral annular velocity were previously evaluated to determine AS. We investigated whether mitral annular velocity was useful for determining of AS.

METHODS

This study consisted of 52 consecutive patients with AF <3 months who converted to the sinus rhythm. Mitral inflow and annular velocities were measured before and after cardioversion. Left atrial appendage (LAA) size and flow were assessed. The average velocity of septal and lateral segments of mitral annulus was considered as the final annular velocity. Thrombus and/or spontaneous echo contrast (SEC) were also investigated.

RESULTS

Of 52 patients, 29 (56%) had AS but 23 did not. There was no significant difference in age, gender, and cardioversion type between two groups. Hypertension was more prevalent in patients without AS compared to those with AS (P = 0.02). Mitral annular systolic and E-wave velocities were comparable in both groups (P > 0.05). Mitral annular A-wave velocity (3.1 +/- 2.9 vs. 7.1 +/- 2.2 cm/s, P < 0.001), and its velocity-time integral (0.27 +/- 0.22 vs. 0.74 +/- 0.19 cm, P < 0.001) were significantly lower in patients with AS compared with those without AS. The annular A-wave velocity < or =3.3 cm/s predicted AS with a sensitivity of 59% and specificity of 76%. It was correlated with mitral inflow A velocity (r = 0.85, P < 0.001), LAA emptying velocity (r = 0.41, P = 0.003) and presence of SEC (r = -0.52, P < 0.001).

CONCLUSION

After cardioversion of AF, mitral annular A-wave velocity may be a new marker to determine AS.

Atria are more susceptible to electroporation than ventricles: implications for atrial stunning, shock-induced arrhythmia and defibrillation failure

BACKGROUND

Defibrillation shock is known to induce atrial stunning, which is electrical and mechanical dysfunction.

OBJECTIVE

We hypothesized that atrial stunning is caused by higher atrial susceptibility to electroporation vs ventricles. We also hypothesize that electroporation may be responsible for early recurrence of atrial fibrillation.

METHODS

We investigated electroporation induced by 10-ms epicardial high-intensity shocks applied locally in atria and ventricles of Langendorff-perfused rabbit hearts (n = 12) using optical mapping.

RESULTS

Electroporation was centered at the electrode and was evident from transient diastolic depolarization and reduction of action potential amplitude and maximum upstroke derivative. Electroporation was voltage-dependent and polarity-dependent and was significantly more pronounced in the atria vs ventricles (P <.01), with a summary 50% of Effective Dose (ED50) for main measured parameters of 9.2 +/- 3.6 V/cm and 13.6 +/- 3.2 V/cm in the atria vs 37.4 +/- 1.5 V/cm and 48.4 +/- 2.8 V/cm in the ventricles, for anodal and cathodal stimuli, respectively. In atria (n = 5), shocks of both polarities (27.2 +/- 1.1 V/cm) transiently induced conduction block and reentry around the inexcitable area. Electroporation-induced ectopic activity was a possible trigger for reentry. However, in the thicker ventricles, electroporation and resulting conduction slowing and block were restricted to the surface only, preventing complete block and arrhythmia. The upstroke morphology revealed that the wave front dived below the electroporated region and resurfaced into unaffected epicardial tissue.

CONCLUSION

We showed that the atria are more vulnerable to electroporation and resulting block and arrhythmia than the ventricles.

Effect of electroporation on cardiac electrophysiology

Defibrillation shocks are commonly used to terminate life-threatening arrhythmias. According to the excitation theory of defibrillation, such shocks are aimed at depolarizing the membranes of most cardiac cells, resulting in resynchronization of electrical activity in the heart. If shock-induced transmembrane potentials are large enough, they can cause transient tissue damage due to electroporation. In this review, evidence is presented that electroporation of the heart tissue can occur during clinically relevant intensities of the external electrical field and that electroporation can affect the outcome of defibrillation therapy, being both pro- and antiarrhythmic.Here, we present experimental evidence for electroporation in cardiac tissue, which occurs above a threshold of 25 V/cm as evident from propidium iodide uptake, transient diastolic depolarization, and reductions of action potential amplitude and its derivative. These electrophysiological changes can induce tachyarrhythmia, due to conduction block and possibly triggered activity; however, our findings provide the foundation for future design of effective methods to deliver genes and drugs to cardiac tissues, while avoiding possible side effects such as arrhythmia and mechanical stunning.

Pulmonary venous flow assessed by Doppler echocardiography in the management of atrial fibrillation

Pulmonary venous blood flow (PVF) visualized by Doppler echocardiography exhibits a pulsatile behavior, which is related to left atrial pressure and function, mitral valve function, and left ventricular compliance. In atrial fibrillation (AF), the disappearance of atrial reverse flow, a decrease in systolic flow with a greater diastolic than systolic flow, a prolonged onset of systolic flow and the appearance of an early systolic reverse flow are characteristic findings. A reduction in systolic PVF expressed by reduced peak velocity, reduced velocity-time integral of systolic flow, and reduced systolic fraction of PVF has been found to be associated with reduced left atrial appendage flow, left atrial spontaneous echo contrast formation, frequency of AF paroxysms and propensity for AF recurrence following restoration of sinus rhythm. Ablation techniques targeting pulmonary vein ostia and adjacent left atrium are promising treatment options to cure AF. Monitoring the PVF response to and adjusting of ablation procedures has been suggested to optimize outcome and prevent complications such as pulmonary vein stenosis. In conclusion, assessment of PVF variables and patterns by Doppler echocardiography seems useful in the management of AF patients. Especially the reduction in systolic PVF may be used as marker for left atrial dysfunction which favors thrombus formation and AF reinitiation. Finally, PVF monitoring has the potential to an increasing role in AF ablation procedures.