Evaluation of transesophageal echocardiography before cardioversion of atrial fibrillation and flutter in nonanticoagulated patients

Comprehensive Analysis of Anticoagulant Therapy in Patients with Isolated Atrial Flutter

Limited comparative data exist regarding the risk of cardiogenic emboli in patients with isolated atrial flutter (AFL). Some studies suggest a lower complication risk in AFL compared to atrial fibrillation (AFib), but methodological limitations and conflicting reports necessitate a comprehensive investigation. Our analysis proposes that isolated AFL carries a lower risk of ischemic events and left atrial thrombus formation than AFib. Importantly, we caution against applying stroke risk assessment approaches designed for AFib to AFL patients, as it may lead to harmful overestimations and unnecessary anticoagulant prescriptions. Furthermore, we highlight the current lack of sufficient data to determine the overall clinical benefit of prolonged anticoagulant therapy in patients with isolated AFL, especially when CHA2DS2-VASc index values are below 4. This review challenges existing perceptions, offering insights into the nuanced risk profiles of the transitional nature of isolated AFL due to the high incidence of AFib development within a year of AFL diagnosis. In conclusion, tailored risk assessments and further research are essential for precise clinical decision-making in this dynamic landscape.

Long-Term Clinical Outcomes Following the WATCHMAN Device Use in Medicare Beneficiaries

BACKGROUND

Long-term outcomes following left atrial appendage occlusion outside clinical trials and small registries are largely unknown. Collecting these data was a condition of US market authorization of the WATCHMAN device. The aim of this analysis was to evaluate the rates of stroke, bleeding, and death among Medicare beneficiaries following left atrial appendage occlusion implantation during initial commercial availability of the WATCHMAN left atrial appendage occlusion device overall and in important subgroups.

METHODS

All Medicare fee-for-service beneficiaries ≥65 years of age who underwent left atrial appendage occlusion from April 1, 2016, to August 31, 2020, were included based on the International Classification of Diseases, Tenth Revision, and Current Procedural Terminology codes. Over a 5-year follow-up period, the cumulative incidence over time of mortality, ischemic stroke, and major bleeding were calculated using the International Classification of Diseases, Tenth Revision, diagnosis codes for the full study cohort and within important prespecified subgroups.

RESULTS

WATCHMAN recipients (n=48 763) were a median of 77 (interquartile range, 72-82) years of age, 42% female, and mostly White (93%). The median CHA2DS2VASc score was 4 (interquartile range, 3-5) with prior major bleeding in 42% and prior stroke in 12%. At 5 years, death occurred in 44%, bleeding in 15% (with higher risk early following implantation), and ischemic stroke in 7%. Each of these end points was more common with greater baseline age. Male patients had greater 5-year mortality than female patients (46.9% versus 40.6%), but there was no difference between sexes in the rates of ischemic stroke (6.6% versus 7.5%) or major bleeding (14.9% for both). WATCHMAN recipients with prior ischemic stroke or a major bleeding event were older and frailer; these groups had higher rates of ischemic stroke, major bleeding, and death.

CONCLUSIONS

Compared with patients enrolled in the pivotal clinical trials, Medicare beneficiaries undergoing WATCHMAN implantation were older, more female, and had more comorbid conditions. Substantial long-term mortality and major bleeding following WATCHMAN reflect the high-risk nature of the patient population, while the ischemic stroke rate was relatively low (<1.5% per year).

Transesophageal Echocardiogram Before Cardioversion in Atrial Fibrillation Patients

Transesophageal echocardiography (TEE) offers an invaluable, non-invasive avenue for diagnosing and managing various cardiac conditions, including atrial fibrillation (AF). As the most common cardiac arrhythmia, AF affects millions and can lead to severe complications. Cardioversion, a procedure to restore the heart's normal rhythm, is frequently conducted on AF patients resistant to medication. Due to inconclusive data, TEE's utility prior to cardioversion in AF patients remains ambiguous. Understanding TEE's potential benefits and limitations in this population could significantly influence clinical practice. This review aims to scrutinize the current literature on the use of TEE before cardioversion in AF patients. The principal objective is to understand TEE's potential benefits and limitations comprehensively. The study seeks to offer a clear understanding and practical recommendations for clinical practice, thereby improving the management of AF patients before cardioversion using TEE. A literature search of databases was conducted using the keywords "Atrial Fibrillation," "Cardioversion" and "Transesophageal echocardiography," resulting in 640 articles. These were narrowed to 103 following title and abstract reviews. After applying exclusion and inclusion criteria with a quality assessment, 20 papers were included: seven retrospective studies, 12 prospective observational studies, and one randomized controlled trial (RCT). Stroke risk associated with direct-current cardioversion (DCC) potentially results from post-cardioversion atrial stunning. Thromboembolic events occur post cardioversion, with or without prior atrial thrombus or cardioversion complications. Generally, cardiac thrombus localizes in the left atrial appendage (LAA), a clear contraindication to cardioversion. Atrial sludge without LAA thrombus in TEE is a relative contraindication. TEE before electrical cardioversion (ECV) in anticoagulated AF individuals is uncommon. In AF patients planned for cardioversion, contrast enhancement facilitates thrombus exclusion in TEE images, reducing embolic events. Left atrial thrombus (LAT) frequently occurs in AF patients, necessitating TEE examination. Despite the increased use of pre-cardioversion TEE, thromboembolic events persist. Notably, patients with post-DCC thromboembolic events had no LA thrombus or LAA sludge. The use of TEE-guided DCC has grown due to its ability to detect atrial thrombi pre-cardioversion, aiding risk stratification. Thrombus in the left atrium also signals an elevated risk of future thromboembolic events in AF patients. While atrial stunning post cardioversion detected by TEE is a significant risk factor for future thromboembolic events, further evidence is required. Therapeutic anticoagulation is essential during and post cardioversion, even if no atrial thrombus is detected. Current data recommends cardioversion guided by TEE, particularly in outpatient settings.

Characteristics of pulmonary vein enlargement in non-valvular atrial fibrillation patients with stroke

PURPOSE

The association between pulmonary vein (PV) dilatation and stroke in non-valvular atrial fibrillation (AF) patients remains unknown.

MATERIALS AND METHODS

We examined the left atrium (LA) and PV in control (n=138) and non-valvular AF patients without (AF group, n=138) and with non-hemorrhagic stroke (AF with stroke group, n=138) using computed tomography.

RESULTS

The LA, LA appendage (LAA), and all PVs were larger in the AF than control patients. The orifice areas of the LAA (5.6±2.2 cm² vs. 4.7±1.7 cm², p<0.001), left superior PV (3.8±1.5 cm² vs. 3.4±1.2 cm², p=0.019), and inferior PV (2.3±1.0 cm² vs. 1.8±0.7 cm², p<0.001) were larger in the AF with stroke than in the AF only group. However, right PVs were not different between the two groups. In a multivariate analysis, the orifice areas of the left superior PV [odds ratio (OR) 1.25, 95% confidence interval (CI) 1.03-1.51, p=0.02], left inferior PV (OR 1.97, 95% CI 1.41-2.75, p<0.001), and LAA (OR 1.30, 95% CI 1.13-1.50, p<0.001) were independent predictors of stroke.

CONCLUSION

Compared to the right PVs, the left PVs and LAA exhibited more significant enlargement in patients with AF and stroke than in patients with AF only. This finding suggests that the remodeling of left-sided LA structures might be related to stroke.

Spontaneous conversion of first onset atrial fibrillation

BACKGROUND/AIM

We studied all patients admitted to hospital with first onset atrial fibrillation (AF) to determine the probability of spontaneous conversion to sinus rhythm and to identify factors predictive of such a conversion.

METHODS

We retrospectively reviewed charts of 438 consecutive patients admitted to hospital with first onset AF from 1 January 2006 to 31 December 2009. The patients were divided into two groups, recent onset AF defined as AF < 48 h or longer lasting AF, defined as AF > 48 h.

RESULTS

Spontaneous conversion occurred in 54% (n = 203; 95% confidence interval: 49-59%). In the group with first onset AF < 48 h, spontaneous conversion occurred in 77%, compared with 36% in the group with first onset AF > 48 h. Logistic regression analysis identified duration of AF as a highly significant predictor of spontaneous conversion to sinus rhythm (odds ratio 5.9; 95% confidence interval: 4.0-8.6, P < 0.001).

CONCLUSIONS

Spontaneous conversion occurred in 54%, increasing to 77% when AF had persisted less than 48 h.

Usefulness of transesophageal echocardiography to confirm clinical utility of CHA2DS2-VASc and CHADS2 scores in atrial flutter

The CHA(2)DS(2)-VASc and CHADS(2) risk stratification schemes are used to predict thromboembolism and ischemic stroke in patients with atrial fibrillation. However, limited data are available regarding the utility of these risk stratification schemes for stroke in patients with atrial flutter. A retrospective analysis of 455 transesophageal echocardiographic studies in patients with atrial flutter was performed to identify left atrial (LA) thrombi and/or spontaneous echocardiographic contrast (SEC). The CHA(2)DS(2)-VASc (Congestive heart failure, Hypertension, Age ≥75 years [doubled risk weight], Diabetes mellitus, previous Stroke/transient ischemic attack [doubled risk weight], Vascular disease, Age 65 to 74 years, Sex) and CHADS(2) (Congestive heart failure, Hypertension, Age ≥75 years, Diabetes mellitus, previous Stroke/transient ischemic attack [double risk weight]) scores were calculated to stratify the risk of stroke or transient cerebrovascular ischemic events. Transesophageal echocardiography revealed LA thrombi in 5.3% and SEC in 25.9% of patients. Using CHADS(2), LA thrombus was found in 2.2% of the low-intermediate-risk group and 8.3% of the high-risk group (p = 0.005). SEC was found in 19.8% of the low-intermediate-risk group and 32% of the high-risk group (p = 0.004). Using CHA(2)DS(2)-VASc, LA thrombus was found in 1.7% of the low-intermediate-risk group and 6.5% of the high-risk group (p = 0.053). SEC was found in 11.8% of the low-intermediate-risk group versus 30.9% of the high-risk group (p = 0.004). The sensitivity for LA thrombus/SEC with a high CHADS(2) and CHA(2)DS(2)-VASc score was 64.8% and 88.7%, respectively (p = 0.0001). The specificity for LA thrombus/SEC with high CHADS(2) and CHA(2)DS(2)-VASc scores was 52.6% and 28.9%, respectively (p = 0.0001). In conclusion, both CHA(2)DS(2)-VASc and CHADS(2) scores are useful for stroke risk stratification in patients with atrial flutter. CHA(2)DS(2)-VASc had greater sensitivity for LA thrombus and SEC detection at the cost of reduced specificity.

Thromboembolism in patients with atrial fibrillation with and without left atrial thrombus documented by transesophageal echocardiography

The incidence of cerebrovascular events (CVEs) was investigated in 95 consecutive patients with atrial fibrillation (AF) with left atrial thrombus (LAT) diagnosed by transesophageal echocardiography (TEE) and in 131 age- and sex-matched AF patients without LAT. Compared with patients without LAT, patients with LAT had a larger left atrial diameter (49 versus 44 mm, P < 0.0001), a lower left ventricular ejection fraction (40% versus 50%, P < 0.0001), a higher prevalence of spontaneous echocardiographic contrast (88% versus 25%, P < 0.001), a reduced left atrial appendage emptying velocity (0.25 versus 0.41 cm/s, P < 0.0001), and less use of antiarrhythmic drugs (61% versus 76%, P = 0.03). Before TEE, the prevalence of prior CVE was higher in LAT patients (20%) compared with patients without LAT (8%) (P = 0.01). Fifty-four of 95 LAT patients (57%) and 81 of 131 non-LAT patients (62%) were on warfarin before TEE. The incidence of prior CVE in LAT patients without warfarin (32%) was higher than that in non-LAT patients without warfarin (10%) (P = 0.02). The mortality rate in LAT patients with an international normalized ratio (INR) >or= 2.0 (42%) was higher than that in patients without LAT and an INR >or= 2.0 (11%) (P < 0.001). Fifty-one of 95 LAT patients (54%) underwent repeat TEE before cardioversion (48 patients received warfarin therapy). The thrombus resolved in 40 of 51 patients (78%) after the first TEE. There was no significant difference in INR between the patients with persistent and resolved LAT. AF patients with persistent LAT had a higher incidence of CVE (45%) than the patients with resolved LAT (5%) (P = 0.003). We suggest that patients with LAT be treated with warfarin to maintain an INR between 2.5 and 3.5 rather than between 2.0 and 3.0 because they are at a high risk for new thromboembolism.

Warfarin Therapy Initiated before Is More Beneficial Than after Transesophageal Echocardiography Detected Left Atrial Thrombus

OBJECTIVE

Warfarin anticoagulation significantly reduces the risk of thromboembolism in patients with atrial fibrillation (AF). However, there are many patients with AF who begin anticoagulation only after left atrial thrombus (LAT) is detected by transesophageal echocardiography (TEE). The impact of anticoagulation in these patients has not been clearly described. The purpose of this study was to investigate the incidence of cerebrovascular accident (CVA) among AF patients who began warfarin before LAT was detected by TEE compared to those who began warfarin only after TEE demonstrated LAT and those did not receive warfarin at any point.

METHOD

Of the 90 consecutive AF patients with LAT (male 48, female 42, age 71.5 +/- 10.1 years), 49 began warfarin more than 3 weeks before TEE (Group I); 29 began warfarin after TEE (Group II); and 12 did not receive warfarin at all (Group III).

RESULTS

The incidence of CVA in Group I (14%, 7/49, prior CVA 5, new CVA after TEE 2) was significantly lower than Group II (45%, 13/29, prior CVA 10, new CVA after TEE 3, P = 0.006) and III (42%, 5/12, prior CVA 3, new CVA after TEE 2, P = 0.047). Patients with persistent LAT had significantly higher incidence (64% vs 23%, P = 0.024) of CVA and lower CVA free survival than those with resolved LAT.

CONCLUSION

The incidence of CVA among AF patients, who began warfarin before LAT detection, is significantly lower than those who began warfarin after LAT detection as well as those who did not receive warfarin at all.

Mild Left Ventricular Dysfunction Is Associated with Thrombogenicity in Cardioembolic Stroke

BACKGROUND

Transesophageal echocardiography (TEE) has been recognized as a valuable tool for identifying the left cardiac thrombus (LCT) or spontaneous echocardiographic contrast (SEC). We aimed to identify risk groups where TEE should be performed in patients with suspected cardioembolic stroke according to magnetic resonance imaging analysis.

METHODS

One hundred and forty-six patients (mean age 64.7 +/- 11.8 years, 101 males) with suspected cardioembolic stroke were analyzed. We used TEE for the presence of LCT and/or SEC as indication of thrombogenicity. We evaluated the association between thrombogenicity and demographic features, stroke risk factors and echocardiographic variables.

RESULTS

The study included 40 patients (27.3%) who showed thrombogenicity (10 LCT and 30 SEC). The independent echocardiographic variables of thrombogenicity were atrial fibrillation (OR 7.14; 95% CI 2.62-19.48; p < 0.001) and left ventricular ejection fraction </=50% (OR 4.01; 95% CI 1.40-11.49; p = 0.01).

CONCLUSION

We recommend that TEE should be considered in patients with mildly reduced left ventricular dysfunction (ejection fraction </=50%) after suspected cardioembolic stroke.

[TEE-guided cardioversion in patients with atrial fibrillation without previous anticoagulation]

A total of 332 patients (mean age 65+/-10 years, 86 female) with nonvalvular atrial fibrillation (AF) of more than 48 hours duration and lack of a sufficient anticoagulation were included. After exclusion of thrombotic material in the left atrium using transesophageal echocardiography (TEE) cardioversion (CV) was performed within 24 hours. At the same time oral anticoagulation (AC) (overlapping with PTT-affecting heparinisation) was started. If thrombi were found by TEE, the examination was repeated after at least four weeks of anticoagulation. If thrombi were absent at this time, CV was performed. Periprocedural embolism was defined as primary endpoint, whereas the detection of atrial thrombi before CV was defined as secondary endpoint. In 33 of the 332 Patients (9.9%) the TEE showed a thrombus in the left atrium respectively the left atrial appendage (n=22) or thrombi could not be excluded (n=11). 383 TEEs were performed without complications in an overall of 332 patients.A total of 305 CV were performed (electrical n=300, pharmacological n=5) and during periprocedural monitoring and in the time of four weeks after CV no thromboembolic complications were observed.TEE-guided CV in patients with AF persisting for more than 48 hours and without previous AC can be considered as a method that is both safe and effective.

Echocardiography in atrial fibrillation

Atrial fibrillation is the most commonly encountered sustained arrhythmia. Echocardiography has augmented the knowledge about etiology and complications of atrial fibrillation. Transthoracic echocardiography allows rapid, safe and comprehensive assessment of cardiac structure and function, and is recommended for all subjects with atrial fibrillation. The use of transesophageal echocardiography has contributed to a better understanding of the thromboembolic risk in patients with atrial fibrillation, especially in the setting of electrical cardioversion. Several investigators have demonstrated the feasibility and safety profile of early cardioversion with short-term anticoagulation in patients with atrial fibrillation and a transesophageal echocardiography negative for atrial thrombi. More recently, transesophageal and intracardiac echocardiography have been employed in patients with atrial fibrillation to monitor percutaneous procedures such as pulmonary veins radiofrequency ablation or left atrial appendage obliteration. In this review the available echocardiographic imaging modalities and their specific role in the evaluation and management in atrial fibrillation are described.

Atrial flutter and the risk of thromboembolism: a systematic review and meta-analysis

PURPOSE

We conducted a systematic review and meta-analysis of observational studies to assess the risk of thromboembolism associated with atrial flutter.

METHODS

MEDLINE, EMBASE, bibliographies, and consultation with clinical experts were used to identify studies that report the risk of thromboembolism associated with attempted cardioversion and longer-term risk in chronic atrial flutter. The review process and data extraction were performed by two reviewers. Study event rates were assessed graphically, and a chi-squared test was used to assess heterogeneity across studies. Meta-regression with weighted logistic regression was used to assess the association between study-level clinical factors and reported thromboembolic event rates.

RESULTS

We found 13 studies that reported the risk of thromboembolism associated with cardioversion of atrial flutter. Short-term event rates ranged from 0% to 7.3%. A chi-squared test for heterogeneity was significant (P < 0.001), so results were not pooled. Instead, a meta-regression analysis was performed, which partly explained the heterogeneity across studies. Studies were more likely to report high event rates when they included patients with a prior history of thromboembolism, and to report lower event rates when at least some patients were anticoagulated or if patients underwent echocardiography before cardioversion. Four studies reported the longer-term risk of thromboembolism, and these suggest a yearly event rate of approximately 3% with sustained atrial flutter.

CONCLUSION

These findings suggest that atrial flutter is indeed associated with an increased risk of thromboembolism, and that clinical factors account for the low event rates reported in some studies.

Antithrombotic Therapy in Atrial Fibrillation

This chapter about antithrombotic therapy in atrial fibrillation (AF) is part of the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy: Evidence Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S-187S). Among the key recommendations in this chapter are the following (all vitamin K antagonist [VKA] recommendations have a target international normalized ratio [INR] of 2.5; range, 2.0 to 3.0): In patients with persistent or paroxysmal AF (PAF) [intermittent AF] at high risk of stroke (ie, having any of the following features: prior ischemic stroke, transient ischemic attack, or systemic embolism, age > 75 years, moderately or severely impaired left ventricular systolic function and/or congestive heart failure, history of hypertension, or diabetes mellitus), we recommend anticoagulation with an oral VKA, such as warfarin (Grade 1A). In patients with persistent AF or PAF, age 65 to 75 years, in the absence of other risk factors, we recommend antithrombotic therapy with either an oral VKA or aspirin, 325 mg/d, in this group of patients who are at intermediate risk of stroke (Grade 1A). In patients with persistent AF or PAF < 65 years old and with no other risk factors, we recommend aspirin, 325 mg/d (Grade 1B). For patients with AF and mitral stenosis, we recommend anticoagulation with an oral VKA (Grade 1C+). For patients with AF and prosthetic heart valves, we recommend anticoagulation with an oral VKA (Grade 1C+); the target INR may be increased and aspirin added depending on valve type and position, and on patient factors. For patients with AF of > or = 48 h or of unknown duration for whom pharmacologic or electrical cardioversion is planned, we recommend anticoagulation with an oral VKA for 3 weeks before and for at least 4 weeks after successful cardioversion (Grade 1C+). For patients with AF of > or = 48 h or of unknown duration undergoing pharmacologic or electrical cardioversion, an alternative strategy is anticoagulation and screening multiplane transesophageal echocardiography (Grade 1B). If no thrombus is seen and cardioversion is successful, we recommend anticoagulation for at least 4 weeks (Grade 1B). For patients with AF of known duration < 48 h, we suggest cardioversion without anticoagulation (Grade 2C). However, in patients without contraindications to anticoagulation, we suggest beginning IV heparin or low molecular weight heparin at presentation (Grade 2C).

Tissue factor expression in atrial endothelia associated with nonvalvular atrial fibrillation: possible involvement in intracardiac thrombogenesis

INTRODUCTION

Tissue factor plays a key role in the extrinsic coagulation pathway and is induced by inflammatory cytokines. Atrial myocarditis has been detected recently in some patients with lone atrial fibrillation. Virchow's triad of low blood flow, hypercoagulability, and endothelial dysfunction, enhances thrombus formation. The present study was designed to elucidate the role of endothelial dysfunction in thrombogenesis associated with nonvalvular atrial fibrillation.

MATERIAL AND METHODS

We investigated tissue factor expression in the endothelia of left atrial appendages obtained from seven patients with nonvalvular atrial fibrillation and cardiogenic thromboembolism. Tissues were divided into 7-13 sections and compared with control specimens from four patients who died of noncardiac events. Expression of tissue factor, von Willebrand factor and tissue factor pathway inhibitor was evaluated by immunohistochemistry.

RESULTS

Histopathologically, inflammatory cells infiltrated the endocardium and all seven patients showed features of persistent myocarditis. Activated T cells [15.3+/-9.4 cells/high power field (HPF, mean+/-S.D.) vs. control 2.2+/-4.4/HPF (P=0.0294)] and a few macrophages [5.1+/-8.4 cells/HPF vs. control 2.4+/-3.5 cells/HPF (P=NS)] infiltrated the endocardium. Tissue factor was overexpressed in the endothelia particularly in tissues containing inflammatory cells and denuded matrix of the endocardium, compared with the control group. Von Willebrand factor, but not tissue factor pathway inhibitor, was also overexpressed in these tissues.

CONCLUSION

Tissue factor expression induced by local inflammation is involved in the pathogenesis of thrombosis in patients with nonvalvular atrial fibrillation.

Transesophageal echocardiography in patients with atrial fibrillation

Over the past decade transesophageal echocardiography (TEE) has become an integral tool in the management of patients with AF. Thrombi can be readily detected and the function of the left atrium and left atrial appendage (LAA) can be easily assessed by this modality. With this knowledge, informed decisions regarding anticoagulation, cardioversion, and the likelihood of restoring and maintaining sinus rhythm can be made. An alternative TEE-guided strategy for achieving sinus rhythm in patients with AF is now available with efficacy and safety similar to the conventional approach. Refinements of this strategy may include the use of low molecular weight heparin to avoid hospitalization in patients planned for cardioversion. Further uses of TEE in patients with AF are in their early stages including evaluation of patients following pulmonary vein radiofrequency ablation and those undergoing percutaneous or surgical closure of the LAA.

Clinical and transthoracic echocardiographic predictors of abnormal transesophageal findings in patients with suspected cardiac source of embolism

BACKGROUND

Approximately 20% of cerebral infarctions are caused by a cardiac source of embolism. Although transesophageal echocardiography (TEE) is a valuable tool for evaluating patients with suspected cardioembolism, its use should be more selective.

OBJECTIVE

We attempted to determine whether risk factors derived from the clinical, ECG, and transthoracic echocardiogram (TTE) would make TEE use more selective and increase its yield.

METHODS

We retrospectively reviewed the records of 108 patients with suspected embolic stroke who had undergone TEE evaluation. We defined the presence of left atrial appendage spontaneous contrast (LAASC), left atrial appendage thrombus (LAAT), patent foramen ovale (PFO), or intraatrial septal aneurysm (IASA) as TEE endpoints suggestive of cardioembolism. We evaluated the association between the TEE endpoints and (1) age greater than 60 years, (2) the presence of atrial flutter (AFl) or atrial fibrillation (AF) on ECG, (3) left ventricular (LV) dysfunction by TTE (mild, LVEF < 40%; severe, LVEF < 25%), and (4) left atrial (LA) size > 4 cm also determined by TTE. The statistical analysis performed was one-way analysis of variance controlling for interactions between different risk factors and the endpoints. RESULTS The strongest independent predictors for the presence of LAASC or LAAT were age greater than 60 years, presence of AFl/AF, and LV systolic dysfunction. There was no association between any of the risk factors with the presence of PFO or IASA.

CONCLUSION

This study demonstrates that clinical characteristics, ECG, and TTE findings can help to better select stroke patients for TEE. Future larger studies are needed to provide more supporting data.

[Systemic embolism after reversion to sinusal rhythm of persistent atrial flutter]

BACKGROUND

The incidence of embolism in atrial flutter has been underestimated in the routine clinical practice.

PATIENTS AND METHODS

In this study the incidence of thromboembolic events after restoration of sinus rhythm (by catheter ablation or cardioversion) was compared in two groups of consecutive patients, with a different anticoagulation protocol. A total of 169 patients were evaluated. A first retrospective analysis of 79 non anticoagulated patients (group I). A second prospective group of 90 patients who were treated with an anticoagulation protocol (group II) similar to that for patients with atrial fibrillation. All had typical atrial flutter of at least one month's duration before the procedure.

RESULTS

The mean age of patients in group I was 61 12 years and the mean left ventricular ejection fraction was 57 6%. Patients in group II had a mean age of 61 10 years and the mean left ventricular ejection fraction was 56 9%. No differences were observed regarding prevalence of structural cardiopathy, arterial hypertension, diabetes mellitus, left ventricular dysfunction, atrial size or atrial fibrillation between the two groups of patients. Four patients in the retrospective analysis (5%) had an embolic event associated with the procedure, compared with 0 (0%) in the group of patients treated with the anticoagulation protocol. The efficient anticoagulation was associated with a lower risk of thromboembolic events (p < 0.05).

CONCLUSIONS

The incidence of embolic events after reversion to sinusal rhythm of persistent atrial flutter can be decreased. These patients should follow the same recommendations of anticoagulation that apply for patients with persistent atrial fibrillation that are going to be reverted to sinus rhythm.

Relationship between left atrial appendage function and left atrial thrombus in patients with nonvalvular chronic atrial fibrillation and atrial flutter

The relationship between the left atrial appendage (LAA) function, as assessed by transesophageal echocardiography, and the incidence of left atrial thrombus was evaluated in 62 patients with nonvalvular chronic atrial fibrillation (AF; n=50) and atrial flutter (AFL; n=12). It was hypothesized that in both AF and AFL not only the LAA flow velocity (LAAFV), but also the frequency of the LAA movement (the LAA flow time, LAAFT) is a major contributing factor to thrombus formation. LAAFT was defined as the average duration of LAA flow with emptying and filling waves. The patients with AF were divided into 2 groups: lone AF (n=14) and non-lone AF (n=36). LAA thrombus was found in 6 patients with none-lone AF. LAAFV was lower and LAAFT was shorter in patients with thrombus as compared with patients without thrombus (12.0+/-2.2 cm/s vs 24.1+/-10.6 cm/s, 68.7+/-1.5 ms vs 72.9+/-3.3 ms, p<0.01, respectively). Patients with AFL had higher LAAFV and longer LAAFT than those with chronic AF. The present data suggest that, in addition to LAAFV, LAAFT characterized LAA function and might serve as a predictor of thrombus formation in chronic AF. With respect to LAA function, patients with lone AF or AFL are at low risk for thrombus formation.

Thromboembolic complications after electrical cardioversion in patients with atrial flutter

PURPOSE

To determine the incidence of thromboembolic complications after cardioversion in patients with atrial flutter.

SUBJECTS AND METHODS

We reviewed 615 electrical cardioversions performed electively in 493 patients with atrial flutter. Embolic complications were evaluated during the 30 days after cardioversion. Follow-up data were obtained by follow-up visits and by contacting the treating physician.

RESULTS

Anticoagulants had been administered in 415 cardioversions (67%). Cardioversion was successful in 570 procedures (93%). Three embolic events (in 3 patients) occurred in the 30 days after 550 successful cardioversions with completed follow-up (0.6% of successful procedures; 95% confidence interval, 0.1% to 1.6%). Two of the 3 patients had not been anticoagulated, whereas the third patient had subtherapeutic oral anticoagulation. No embolic event occurred in procedures performed with adequate anticoagulation. The incidence of embolism in patients regardless of subtherapeutic anticoagulation was 1% (3 of 303 successful cardioversions).

CONCLUSIONS

We observed a low (0.6%) incidence of postcardioversion thromboembolic complications in patients with atrial flutter. Embolic events did not occur in patients with adequate anticoagulation.

Different patterns of interatrial conduction in clockwise and counterclockwise atrial flutter

BACKGROUND

The terms counterclockwise (CC) and clockwise (C) atrial flutter (Afl) are used to describe right atrial activation around the tricuspid valve in the left anterior oblique view. The manner in which the left atrium is activated, as reflected by coronary sinus (CS) recordings, has not been systematically evaluated.

METHODS AND RESULTS

Nine patients with both CC and C Afl underwent electrophysiological study with CS recordings during both rhythms with the use of a decapolar catheter with the tip placed in the distal CS. Patterns of CS activation during each type of Afl as well as during during sinus rhythm were categorized into 1 of 3 patterns: sequential proximal-to-distal, sequential distal-to-proximal, and fused, indicating activation from different directions. In 7 of 9 patients, the pattern of CS activation in CC Afl and C Afl differed, with a proximal-to-distal pattern in CC Afl and a fused pattern in C Afl. In 2 patients, pacing the high right atrial septum near the presumed site of Bachmann's bundle in sinus rhythm showed a similar fused pattern of CS activation.

CONCLUSIONS

These results demonstrate different patterns of CS activation in CC Afl and C Afl in the majority of patients and are consistent with a model in which the left atrium is activated predominantly over Bachmann's bundle during C Afl and over the CS os in CC Afl. These findings may have implications for maintenance of Afl, interpretation of flutter wave morphology on surface ECG, and left atrial mechanical function in Afl.

Role of transesophageal echocardiography-guided cardioversion of patients with atrial fibrillation

Electrical cardioversion of patients with atrial fibrillation (AF) is frequently performed to relieve symptoms and improve cardiac performance. Patients undergoing cardioversion are treated conventionally with therapeutic anticoagulation for three weeks before and four weeks after cardioversion to decrease the risk of thromboembolism. A transesophageal echocardiography (TEE)-guided strategy has been proposed as an alternative that may lower stroke and bleeding events. Patients without atrial cavity thrombus or atrial appendage thrombus by TEE are cardioverted on achievement of therapeutic anticoagulation, whereas cardioversion is delayed in higher risk patients with thrombus. The aim of this review is to discuss the issues and controversies associated with the management of patients with AF undergoing cardioversion. We provide an overview of the TEE-guided and conventional anticoagulation strategies in light of the recently completed Assessment of Cardioversion Using Transesophageal Echocardiography (ACUTE) clinical trial. The two management strategies comparably lower the patient's embolic risk when the guidelines are properly followed. The TEE-guided strategy with shorter term anticoagulation may lower the incidence of bleeding complications and safely expedite early cardioversion. The inherent advantages and disadvantages of both strategies are presented. The TEE-guided approach with short-term anticoagulation is considered to be a safe and clinically effective alternative to the conventional approach, and it is advocated in patients in whom earlier cardioversion would be clinically beneficial.

Management of patients with syncope and cardiac arrhythmias in an emergency department observation unit

Syncope is an ideal condition for the emergency observation setting because of its difficulty in diagnosis, many causes, high liability, and variable diagnostic approaches. Hospital admissions can be averted with appropriate patient selection for a short-term observation period. Atrial fibrillation is a common presenting condition in the emergency department. With aggressive management, the appropriately selected patient can have restoration of sinus rhythm and be safely discharged home.

Transesophageal echocardiography (TEE) in atrial fibrillation

Transesophageal echocardiography has given new insight into the pathogenesis of the thromboembolic sequelae of AF and expanded the available therapeutic options. Studies to date indicate that TEE-guided cardioversion is a safe and reasonable approach when the clinical situation warrants prompt restoration of sinus rhythm. Whether widespread use of this strategy offers further benefit remains to be established, although there are theoretical advantages to such an approach. The potential for earlier cardioversion using a TEE-guided approach may facilitate the achievement and maintenance of sinus rhythm. In the long term, earlier restoration of sinus rhythm prevents adverse atrial remodeling, lowers embolic risk, and may improve cardiac performance and functional status. Thromboembolic sequelae (either cardioversion-related or as a result of chronic AF) remain the most devastating complications of AF. Every attempt to minimize this risk should be pursued aggressively. Information gathered from TEE has helped to elucidate the mechanisms responsible for postcardioversion embolism and has emphasized the importance of anticoagulation during and after the restoration of sinus rhythm. TEE also has the potential to further risk stratify patients with AF. Ultimately, a subset of patients may be identified who require more intense anticoagulation (i.e., those with dense SEC or thrombus, or persistent thrombus after prolonged anticoagulation) or in whom cardioversion may be deferred entirely. Likewise, TEE also may prove to be useful in identifying patients with a low-clinical risk profile who may be treated with aspirin alone and patients in whom warfarin may be superior. The results of the ACUTE study should help to further define the role of TEE in the management of patients with AF. Additional clinical studies are needed to address some of the issues that have been raised and to allow for optimal use of TEE in this patient population.

Efficacy of anticoagulation in resolving left atrial and left atrial appendage thrombi: A transesophageal echocardiographic study

BACKGROUND

Transesophageal echocardiography (TEE) is the gold standard for evaluation of the left atrium and the left atrial appendage (LAA) for the presence of thrombi. Anticoagulation is conventionally used for patients with atrial fibrillation to prevent embolization of atrial thrombi. The mechanism of benefit and effectiveness of thrombi resolution with anticoagulation is not well defined.

METHODS AND RESULTS

We used a TEE database of 9058 consecutive studies performed between January 1996 and November 1998 to identify all patients with thrombi reported in the left atrium and/or LAA. One hundred seventy-four patients with thrombi in the left atrial cavity (LAC) and LAA were identified (1.9% of transesophageal studies performed). The incidence of LAA thrombi was 6.6 times higher than LAC thrombi (151 vs 23, respectively). Almost all LAC thrombi were visualized on transthoracic echocardiography (90.5%). Mitral valve pathology was associated with LAC location of thrombi (P <.0001), whereas atrial fibrillation or flutter was present in most patients with LAA location of thrombi. Anticoagulation of 47 +/- 18 days was associated with thrombus resolution in 80.1% of the patients on follow-up TEE. Further anticoagulation resulted in limited additional benefit.

CONCLUSIONS

LAC thrombi are rare and are usually associated with mitral valve pathology. Transthoracic echocardiography is effective in identifying these thrombi. LAA thrombi occur predominantly in patients with atrial fibrillation or flutter. Short-term anticoagulation achieves a high rate of resolution of LAA and LAC thrombi but does not obviate the need for follow-up TEE.

Spontaneous echo contrast: where there's smoke there's fire

Left atrial (LA) spontaneous echo contrast (SEC), or "smoke," is a frequent finding on transesophageal echocardiography (TEE), but it is rarely detected with transthoracic echocardiography. LA SEC is characterized by dynamic smoke-like echoes within the LA cavity or appendage. Most patients with LA SEC have atrial arrhythmias, mitral stenosis, or a mitral valve prosthesis, and they have an enlarged LA, conditions that are associated with LA stasis. Conversely, mitral regurgitation is protective against LA SEC. LA SEC is present in almost all patients with LA thrombus and is associated with previous embolic events in many patient populations. In patients with nonvalvular atrial fibrillation, LA SEC predicts future embolism and death. LA SEC may therefore assist in selecting patients with atrial fibrillation or with mitral stenosis and sinus rhythm who benefit the most from anticoagulation. Hematological studies have shown that LA SEC is a marker of an hypercoagulable state. LA SEC is a manifestation of red cell aggregation, arising from an interaction between red cells and plasma proteins such as fibrinogen, at low shear rates. LA SEC does not require platelets. The detection of LA SEC on ultrasound arises from the increased amplitude of backscatter from red cell aggregates rather than single cells. Patients with LA SEC should be considered for anticoagulant therapy and may require correction of underlying cardiovascular abnormalities. Future directions in LA SEC include further assessment of integrated backscatter for quantification, assessment of its prognostic role in clinically low-risk patients with nonvalvular AF, and novel pharmacological treatment.

Risk of thromboembolism in acute atrial fibrillation or atrial flutter

Atrial fibrillation (AF) is the most common sustained cardiac dysrhythmia, predominating in the elderly, with stroke as a potentially devastating complication. Prevention of the thromboembolic sequelae from AF remains a central focus of practicing clinicians. Although the risk of thromboembolism in chronic AF is well recognized, less is known about the potential risk of systemic embolism in acute AF. In addition, recent data support the notion of a group at considerable risk of embolism from atrial flutter, an arrhythmia typically believed to bestow little increased risk of thromboembolism. The mechanism of thrombus formation, embolization, and resolution in atrial arrhythmias is not well defined, particularly in that of acute AF or atrial flutter. The traditional concept proposes that atrial thrombus forms only after > 2 days of AF and embolizes by being dislodged from increases in shear forces. This widely accepted concept further holds that newly formed atrial thrombus, in the setting of AF, organizes over a span of 14 days. The results of studies based on observations from transesophageal echocardiography examinations have provided provocative insight into the temporal sequence of atrial thrombus formation, embolization, and resolution in AF or atrial flutter and have expanded the traditional concept of thromboembolism in these atrial dysrhythmias. Namely, left atrial thrombus may form before the onset of AF in the face of sinus rhythm. Conversion to sinus rhythm may increase the thrombogenic milieu of the left atrium. Importantly, atrial thrombus may form in the acute phase of AF. Last, thrombi may require > 14 days to become immobile or to resolve. Findings similar to those of acute AF have been reported in patients with atrial flutter and coexisting cardiac pathology. On the basis of these emerging insights fostered by the use of transesophageal echocardiography, it appears appropriate to consider anticoagulation in patients presenting with acute AF or atrial flutter with coexisting cardiac pathology predisposing to left atrial thrombus.

Timing of thromboembolic events after electrical cardioversion of atrial fibrillation or flutter: a retrospective analysis

Pooled data from 32 studies were reviewed to assess the timing of thrombolic complications after cardioversion of atrial fibrillation or flutter. We found that 98% of embolic episodes occurred within 10 days of cardioversion.

Risk of thromboembolic events in patients with atrial flutter

Based on multiple studies, clear, guided anticoagulation therapy is recommended for patients with atrial fibrillation. The value of anticoagulation therapy in patients with atrial flutter, however, is less well established. Little is known about the incidence of thromboembolism in patients with atrial flutter. We evaluated the risk of thromboembolism in 191 consecutive unselected patients referred for treatment of atrial flutter. A history of embolic events was noted in 11 patients. Acute embolism (<48 hours) occurred in 4 patients (3 after direct current cardioversion, 1 after catheter ablation). During follow-up of 26+/-18 months, 9 patients experienced thromboembolic events. During the follow-up, the overall embolic event rate (including acute embolism and thromboembolic events during follow-up) was 7 % in this patient population. Risk indicators for an embolic event in an univariate analysis were organic heart disease (p = 0.037), depressed left ventricular function (p = 0.02), history of systemic hypertension (p = 0.004), and diabetes mellitus (p = 0.0038). Using multivariate analysis, a history of hypertension was the only independent predictor for elevated embolic risk in this patient population (odds ratio = 6.5; 95% confidence intervals 1.5 to 45). Thus, the thromboembolic risk is higher than previously recognized for patients with atrial flutter. Anticoagulation therapy may decrease this risk.

Acute treatment of atrial fibrillation

Atrial fibrillation (AFib) is a common clinical entity, responsible for significant morbidity and mortality, but it also accounts for a large percentage of healthcare dollar expenditures. Efforts to treat this arrhythmia in the past have focused on subacute antithrombotic therapy and eventually use of antiarrhythmic drugs for maintenance of sinus rhythm. However, there has been a growing interest in the concept of acute electrical and pharmacologic conversion. This treatment strategy has a number of benefits, including immediate alleviation of patient symptoms, avoidance of antithrombotic therapy, and prevention of electrophysiologic remodeling, which is thought to contribute to the perpetuation of the arrhythmia. There is also increasing evidence that this is a cost-effective strategy in that it may obviate admission to the hospital and the cost of long-term therapy. This article represents a summary of the treatments that may be used acutely to control the ventricular response to AFib, prevent thromboembolic events, and provide for acute conversion either pharmacologically or electrically. It includes information on modalities that are currently available and those that are under active development. We anticipate that an active, acute treatment approach to AFib and atrial flutter will become the therapeutic norm in the next few years, especially as the benefits of these interventions are demonstrated in clinical trials.

Thromboembolism in chronic atrial flutter: is the risk underestimated?

OBJECTIVES

We sought to evaluate the risk of thromboembolic events in the presence of chronic atrial flutter and to determine the impact of anticoagulation therapy, if any, on this risk.

BACKGROUND

Thromboembolic events are thought to be rare after cardioversion of atrial flutter.

METHODS

This study was a retrospective analysis of 110 consecutive patients referred to the electrophysiology laboratory for cardioversion of chronic atrial flutter from 1986 to 1996. Atrial flutter was present for at least 6 months. Of the 110 patients reviewed, 100 had adequate information available regarding the effectiveness of anticoagulation (mean age 64 years, range 27 to 86; 75 men, 25 women; mean left ventricular ejection fraction 42%).

RESULTS

Thirteen patients (13%) had a thromboembolic event. Of these, seven were attributable to causes other than atrial flutter. In the remaining six patients (6%), thromboembolic events occurred during a rhythm of atrial flutter or after cardioversion to sinus rhythm. Other causes of thromboembolism were excluded. Effective anticoagulation was associated with a decreased risk of thromboembolism (p = 0.026).

CONCLUSIONS

Patients with chronic atrial flutter are at an increased risk of thromboembolic events. Effective anticoagulation may decrease this risk.

The medical management of atrial fibrillation

Atrial fibrillation is an extremely common arrhythmia that is associated with significant sequelae. Certain aspects of therapy, such as anticoagulation, are studied in well-constructed randomized trials. Other therapy, such as the maintenance of sinus rhythm with antiarrhythmic agents, is supported by limited evidence. This article reviews the epidemiology and medical treatment of this arrhythmia, addressing anticoagulation, ventricular rate control, and restoration and maintenance of sinus rhythm. Randomized trials in progress that attempt to answer important questions in the management of atrial fibrillation are also discussed.

Left atrial appendage function in patients with atrial flutter

OBJECTIVE

To determine whether echocardiographic markers thromboembolic risk differ between patients with pure atrial flutter and patients with atrial flutter and intermittent atrial fibrillation.

DESIGN

Patients with atrial flutter were followed up prospectively for 12 months to identify intermittent atrial fibrillation. After the follow up period, transthoracic and multiplane transoesophageal echocardiography were performed to assess left atrial chamber and appendage size, peak emptying velocities, and emptying fraction of the left atrial appendage. The presence of spontaneous echo contrast was also determined.

SETTING

Tertiary cardiac care centre.

PATIENTS

20 consecutive patients with atrial flutter; 11 healthy subjects in sinus rhythm served as controls.

RESULTS

Intermittent atrial fibrillation was documented in 11 patients by Holter monitoring or surface ECG; atrial fibrillation was not found in the other nine patients. Compared with the patients with pure atrial flutter, patients with atrial flutter and intermittent atrial fibrillation had larger left atrial chamber (mean (SD) 4.5 (0.6) v 3.8 (0.5) cm; 95% confidence interval 0.2 to 1.2; P = 0.01) and appendage areas (6.7 (2.2) v 4.8 (4.9) cm; 95% CI 0.4 to 3.5; P = 0.02), lower left atrial appendage emptying fractions (33 (11)% v 52 (11)%; 95% CI 8 to 29; P = 0.008), and also lower left atrial appendage emptying velocities (0.44 (0.21) v 0.79 (0.27) m/s; 95% CI 0.13 to 0.56; P = 0.005). In addition, a higher incidence of spontaneous echo contrast (11% v 36%) was observed in patients with atrial flutter and intermittent atrial fibrillation.

CONCLUSIONS

Left atrial appendage function is depressed and spontaneous echo contrast more frequent in patients with atrial flutter and intermittent atrial fibrillation, as opposed to patients with pure atrial flutter. These data support the concept that patients with atrial flutter and intermittent atrial fibrillation have an increased risk of thromboembolic events and should therefore receive adequate anticoagulant treatment.

Clinical variables affecting recovery of left atrial mechanical function after cardioversion from atrial fibrillation

OBJECTIVES

We sought to evaluate the effect of clinical factors on recovery of atrial function after cardioversion for atrial fibrillation.

BACKGROUND

Lack of effective mechanical atrial function (EMAF) after cardioversion of atrial fibrillation predisposes to thromboembolic complications and delays improvement in functional capacity.

METHODS

Fifty-two patients underwent cardioversion (group I, electrical cardioversion, n = 40; group II, pharmacologic or spontaneous cardioversion, n = 12) for atrial fibrillation. Serial transmitral inflow Doppler variables were recorded after cardioversion until EMAF (atrial filling velocity > 0.50 m/s) was seen. Clinical variables (age, duration of atrial fibrillation, left ventricular ejection fraction, left atrial diameter, underlying cardiovascular disease, antiarrhythmic drug therapy and mode of cardioversion) were tested for an association with the outcomes of recovery of atrial function by day 3 and day 7.

RESULTS

Effective mechanical atrial function recovered in 68% of patients by day 3 and in 76% by day 7 after cardioversion. The mode of cardioversion was significantly associated with recovery of atrial function by day 3 in bivariate and multivariate analyses (odds ratio 0.12, 95% confidence interval 0.01 to 1.0, for electrical cardioversion). None of the variables had an association with recovery of atrial function by day 7. Group I patients took a longer time to recover atrial function than group II patients (p = 0.012). In addition, group I patients had a significantly lower peak atrial filling velocity (mean [+/-SD] 0.39 +/- 0.19 m/s vs. 0.56 +/- 0.16 m/s) and a higher early filling to atrial filling velocity ratio (2.5 +/- 1.2 vs. 1.5 +/- 0.5) after cardioversion.

CONCLUSIONS

A high proportion of patients recover EMAF within 1 week after cardioversion. Patients who undergo electrical cardioversion display a greater degree and a longer duration of mechanical atrial dysfunction than those who convert pharmacologically or spontaneously.

Transesophageal echocardiographic predictors for maintenance of sinus rhythm after electrical cardioversion of atrial fibrillation

The aim of this study was to assess the value of transesophageal echocardiography (TEE) in patients with atrial fibrillation in predicting restoration and maintenance of sinus rhythm after electrical cardioversion. TEE was performed in 62 patients with atrial fibrillation before their first elective cardioversion. Clinical variables evaluated were: age, gender, duration, and etiology of atrial fibrillation. TEE variables included: left atrial (LA) length, width, and size, LA annulus size, as well as presence of LA spontaneous contrast, thrombus and mitral regurgitation, LA appendage size and flow, and left ventricular function. Based on initial outcome of cardioversion, patients were grouped into patients who remained in atrial fibrillation and in whom sinus rhythm was restored. The latter group of patients was followed for 1 year, and grouped into patients who reverted to atrial fibrillation and in whom sinus rhythm was maintained. Successful cardioversion was achieved in 50 of 62 patients (81%). None of the clinical or TEE variables were related to initial outcome. At 1-year follow-up, 29 of 50 patients (58%) who underwent successful cardioversion continued to have sinus rhythm. The following variables were related to maintenance of sinus rhythm: duration of atrial fibrillation (6.7 +/- 7.3 vs 2.0 +/- 2.4 months; p < 0.005); LA length (6.2 +/- 0.7 vs. 5.5 +/- 1.0 cm; p < 0.008); width (5.1 +/- 0.5 vs. 4.5 +/- 0.7 cm; p < 0.002); size (26.4 +/- 5.0 vs 19.8 +/- 6.5 cm2; p < 0.0005); annulus size (4.0 +/- 0.2 vs 3.7 +/- 0.3 cm; p < 0.0005); presence of LA spontaneous contrast (13 [62%] vs 4 [14%]; p < 0.002), and LA appendage flow (19 +/- 8 vs 36 +/- 15 cm/s; p < 0.0005). In multivariate logistic regression analysis, LA annulus size, but especially LA appendage flow, were significantly associated with maintenance of sinus rhythm. Thus, in TEE-guided electrical cardioversion of atrial fibrillation, variables often used to assess thromboembolic risk may also be used to predict 1-year outcome of cardioversion.

Risk of thromboembolism in chronic atrial flutter

Anticoagulant therapy is not conventionally used in the treatment of patients with atrial flutter. This recommendation has been based on sparse clinical experience, and recent preliminary reports suggest a significant risk of thromboembolism for these patients. A retrospective study was undertaken to assess the frequency of thromboembolic events as well as potential risk factors for these events in a cohort of patients with atrial flutter referred for radiofrequency ablation treatment. Eighty-six consecutive patients with a primary diagnosis of atrial flutter were evaluated. A history of embolic events was noted in 12 of 86 patients (14%) with atrial flutter, with an annual risk of approximately 3%. There were no differences in the prevalence of coronary artery disease, cardiomyopathy, valvular disease, or atrial fibrillation between the 2 groups of patients having an embolic event and those of patients without embolic events. Left ventricular function and left atrial size were also similar between the 2 groups. The only significant risk factor was hypertension (p < 0.05). However, in a regression model with other clinical variables (i.e., age, gender, left atrial size, presence or absence of any cardiac disease, length of time in flutter, left ventricular function, type of flutter, flutter cycle length, type of secondary arrhythmias) no significant predictors were found. Patients with transient ischemic attacks or pulmonary emboli were then excluded from the analysis in order to compare the thromboembolic risk in the present study to that reported in major atrial fibrillation trials. The overall risk becomes 7% (6 of 86), which over a mean follow-up period of 4.5 years yields an annual risk of approximately 1.6%. Although this risk is only 1/3 of that for patients with atrial fibrillation, this risk is higher than previously recognized for patients with chronic atrial flutter. Anticoagulant therapy should be seriously considered for these patients.

Prevalence of thrombus, spontaneous echo contrast, and atrial stunning in patients undergoing cardioversion of atrial flutter. A prospective study using transesophageal echocardiography

BACKGROUND

Several studies have shown that patients undergoing cardioversion of atrial fibrillation have a high prevalence of of atrial thrombus and spontaneous echo contrast and frequently develop atrial stunning after restoration of sinus rhythm. These findings are strongly associated with increased risk of embolism in these patients. However, little is known about the prevalence of these markers of thromboembolism in patients undergoing cardioversion of atrial flutter.

METHODS AND RESULTS

We performed transesophageal echocardiography in 47 consecutive, nonanticoagulated patients scheduled for elective cardioversion of atrial flutter. In patients who underwent successful cardioversion, mitral inflow velocity was recorded by transthoracic pulsed Doppler examination immediately after restoration of sinus rhythm. All patients were men (mean age, 65 +/- 10 years). Mean duration of flutter was 4 +/- 9 weeks. Atrial thrombus and/or spontaneous echo contrast were found in 16 patients (34%). Left atrial thrombus was seen in 5 patients (11%), either with (n = 4) or without spontaneous contrast. Of 40 patients with successful cardioversion, atrial mechanical activity was absent in 28% immediately after restoration of sinus rhythm.

CONCLUSIONS

Our findings suggest that contrary to traditional teaching, atrial thrombus and spontaneous contrast are not uncommon in patients with atrial flutter and cardioversion may be associated with increased risk of thromboembolism.

Cost-effectiveness of transesophageal echocardiographic-guided cardioversion: a decision analytic model for patients admitted to the hospital with atrial fibrillation

OBJECTIVES

Using a decision-analytic model, we sought to examine the cost-effectiveness of three strategies for cardioversion of patients admitted to the hospital with atrial fibrillation.

BACKGROUND

Transesophageal echocardiographic (TEE)-guided cardioversion has been proposed as a method for early cardioversion of patients with atrial fibrillation. The cost-effectiveness of this approach, relative to conventional therapy, has not been studied.

METHODS

We ascertained the cost per quality-adjusted life-year (QALY) of three strategies: 1) conventional therapy--transthoracic echocardiography (TTE) and warfarin therapy for 1 month before cardioversion; 2) initial TTE, followed by TEE and early cardioversion if no thrombus is detected; 3) initial TEE, with early cardioversion if no thrombus is detected. With strategies 2 and 3, if a thrombus is seen, follow-up TEE is performed. If no thrombus is seen, cardioversion is then performed. All strategies utilized anticoagulation before and extending for 1 month after cardioversion. Life expectancy, utilities (quality-of-life weights) and event probabilities were ascertained from published reports. Cost estimates were based on published data and hospital accounting information.

RESULTS

Transesophageal echocardiographic-guided early cardioversion (strategy 3: cost $2,774, QALY 8.49) dominates TTE/TEE-guided cardioversion (strategy 2: cost $3,106, QALY 8.48) and conventional therapy (strategy 1: cost $3,070, QALY 8.48) because it is the least costly with similar effectiveness. Sensitivity analyses demonstrated that TEE-guided cardioversion (strategy 3) dominates conventional therapy if the risk of stroke after TEE negative for atrial thrombus is slightly less than that after conventional therapy (baseline estimate 0.8%). The results also depend on the risk of major hemorrhage but are less sensitive to baseline estimates of morbidity from TEE, cost of TTE, cost of hospital admission for cardioversion and utilities for health states.

CONCLUSIONS

On the basis of a decision-analytic model, TEE-guided early cardioversion, without TTE, is a reasonable cost-saving alternative to conventional therapy for patients admitted to the hospital with atrial fibrillation. Such a strategy appears particularly beneficial for patients with an increased risk of hemorrhagic complications. Future clinical studies examining the TEE strategy should consider eliminating initial TTE and carefully assess both the thromboembolic and hemorrhagic risk.

Thromboembolism following cardioversion of "common" atrial flutter. Risk factors and limitations of transesophageal echocardiography

Based on multiple recent studies, anticoagulant therapy is recommended prior to elective cardioversion for patients with atrial fibrillation of more than 24 h duration. The value of anticoagulation in patients with atrial flutter, however, is less well established. Published recommendations for pericardioversion anticoagulation of atrial fibrillation often do not extend to patients with atrial flutter. We evaluated the risk of thromboembolism in our patient population undergoing cardioversion for atrial flutter. Over a period of 30 months, clinically indicated electrical cardioversions were performed in 41 patients with "common" atrial flutter. Sixteen of these patients underwent transesophageal echocardiograms immediately prior to cardioversion to exclude a left atrial thrombus. Three of the 41 patients with atrial flutter developed neurologic ischemic syndromes within 48 h of elective cardioversion. All three patients who developed ischemic neurologic complications had undergone transesophageal echocardiography immediately prior to cardioversion and did not have any evidence of left atrial clot. One patient had cardiomyopathy and the other two had left ventricular hypertrophy. Thus, electrical cardioversion without anticoagulation in patients with atrial flutter and associated heart disease is associated with a risk of thromboembolic events. A normal transesophageal echocardiogram is of doubtful value in prevention of thromboembolic complications.

Left atrial appendage thrombus in atrial flutter with no associated heart disease

The risk of cardioembolic events and the role of anti-coagulation therapy in the management of patients with lone atrial flutter is not well defined in the medical literature. We report the case of an otherwise healthy 42-year-old man with chronic established atrial flutter, unassociated with any other heart disease or systemic illness, with transesophageal echocardiographic findings of a mobile left atrial appendage thrombus. The literature to date, potential mechanisms, and recommendations are discussed. The role of transesophageal electrocardiography and anticoagulation in atrial flutter may need to be considered more seriously, especially if atrial flutter has been present for a prolonged period of time.