Left Atrial Appendage Occlusion Eliminates the Need for Warfarin

Left Atrial Thrombus-Are All Atria and Appendages Equal?

Although the left atrial appendage (LAA) seems useless, it has several critical functions that are not fully known yet, such as the causes for being the main origin of cardioembolic stroke. Difficulties arise due to the extreme range of LAA morphologic variability, making the definition of normality challenging and hampering the stratification of thrombotic risk. Furthermore, obtaining quantitative metrics of its anatomy and function from patient data is not straightforward. A multimodality imaging approach, using advanced computational tools for their analysis, allows a complete characterization of the LAA to individualize medical decisions related to left atrial thrombosis patients.

Left Atrial Thrombus-Are All Atria and Appendages Equal?

Although the left atrial appendage (LAA) seems useless, it has several critical functions that are not fully known yet, such as the causes for being the main origin of cardioembolic stroke. Difficulties arise due to the extreme range of LAA morphologic variability, making the definition of normality challenging and hampering the stratification of thrombotic risk. Furthermore, obtaining quantitative metrics of its anatomy and function from patient data is not straightforward. A multimodality imaging approach, using advanced computational tools for their analysis, allows a complete characterization of the LAA to individualize medical decisions related to left atrial thrombosis patients.

CT assessment of the left atrial appendage post-transcatheter occlusion - A systematic review and meta analysis

BACKGROUND

Transesophageal echocardiography (TEE) is the standard imaging modality used to assess the left atrial appendage (LAA) after transcatheter device occlusion. Cardiac computed tomography angiography (CCTA) offers an alternative non-invasive modality in these patients. We aimed to conduct a comparison of the two modalities.

METHODS

We performed a comprehensive systematic review of the current literature pertaining to CCTA to establish its usefulness during follow-up for patients undergoing LAA device closure. Studies that reported the prevalence of inadequate LAA closure on both CCTA and TEE were further evaluated in a meta-analysis. 19 studies were used in the systematic review, and six studies were used in the meta-analysis.

RESULTS

The use of CCTA was associated with a higher likelihood of detecting LAA patency than the use of TEE (OR, 2.79, 95% CI 1.34-5.80, p ​= ​0.006, I2 ​= ​70.4%). There was no significant difference in the prevalence of peridevice gap ≥5 ​mm (OR, 3.04, 95% CI 0.70-13.17, p ​= ​0.13, I2 ​= ​0%) between the two modalities. Studies that reported LAA assessment in early and delayed phase techniques detected a 25%-50% higher prevalence of LAA patency on the delayed imaging.

CONCLUSION

CCTA can be used as an alternative to TEE for LAA assessment post occlusion. Standardized CCTA acquisition and interpretation protocols should be developed for clinical practice.

Advances in the management of atrial fibrillation with a special focus on non-pharmacological approaches to prevent thromboembolism: a review of current recommendations

Atrial fibrillation (AFIB) is the most common heart rhythm abnormality and is associated with significant morbidity and mortality. While the treatment of AFIB involves strategies of rate with or without rhythm control, it is also essential to strategize appropriate therapies to prevent thromboembolic complications arising from AFIB. Previously, anticoagulation was the main treatment option which exposed patients to higher than usual risk of bleeding. However, with the advent of new technology, novel therapeutic options aimed at surgical or percutaneous exclusion or occlusion of the left atrial appendage in preventing thromboembolic complications from AFIB have evolved. This review evaluates recent advances and therapeutic options in treating AFIB with a special focus on both surgical and percutaneous interventions which can reduce and/or eliminate thromboembolic complications of AFIB.

Low vitamin D levels predict left atrial thrombus in nonvalvular atrial fibrillation

BACKGROUND AND AIMS

We determined the association between left atrial (LA) thrombus occurrence and a non-classic risk marker, plasma levels of vitamin D, in atrial fibrillation (AF) patients on continuous non-vitamin K antagonist oral anticoagulant (NOAC) therapy for ≥4 weeks. Low levels of plasma 25-hydroxy vitamin D (25-OHD) are predictive of fatal stroke. Vitamin D has anticoagulant effects on the coagulation cascade, which are indirectly targeted by NOAC therapy. The impact of plasma levels of vitamin D on the rate of LA thrombus detected by transesophageal echocardiography (TEE) in AF patients is unknown.

METHODS AND RESULTS

We enrolled 201 (133 female) AF patients who were using continuous NOAC therapy for ≥4 weeks. All patients underwent transthoracic and TEE examination. Serum concentrations of 25-OHD, C-reactive protein (CRP) levels, CHA₂DS₂-VASc scores and parameters, LA size, and left ventricle ejection fraction (LVEF) were examined before the TEE procedure. LA thrombus occurrence was independently associated with serum levels of 25-OHD (OR: 0.884; 95% CI: 0.839-0.932; P < 0.001), LA diameter (OR: 1.120; 95% CI: 1.038-1.209; P = 0.003), and LVEF(OR: 0.944; 95% CI: 0.896-0.995; P = 0.032). Dense spontaneous echo contrast (SEC) presence was also inversely associated with 25-OHD concentrations.

CONCLUSIONS

Low 25-OHD levels, as a non-classic risk factor, were independently and significantly associated with dense SEC and LA thrombus occurrence in AF patients under NOAC therapy, as well as LA enlargement and decreased LVEF. Further large-scale studies are needed to explain the role of vitamin D deficiency, or efficacy of replacement, on LA thrombus occurrence.

Left Atrial Appendage Thrombi Formation in Japanese Non-Valvular Atrial Fibrillation Patients During Anticoagulation Therapy - Warfarin vs. Direct Oral Anticoagulants

BACKGROUND

Atrial fibrillation (AF) is a common cardiac arrhythmia, associated with increased cardiovascular morbidity and mortality including thromboembolic events. The aims of this study were to assess the prevalence of left atrial appendage (LAA) thrombi in Japanese non-valvular atrial fibrillation (NVAF) patients undergoing preprocedural transesophageal echocardiography (TEE) during anticoagulation therapy, and to compare the efficacy of warfarin and direct oral anticoagulants (DOAC).

METHODS AND RESULTS

This retrospective study reviewed records of 559 consecutive NVAF patients (445 men; age, 62±11 years) undergoing preprocedural TEE following at least 3 weeks of anticoagulation therapy. Of these, 275 patients had non-paroxysmal AF (49%). LAA thrombus was observed in 15 patients (2.7%). The prevalence of LAA thrombi was similar between the DOAC group (2.6%) and the warfarin group (2.8%, P=0.86). No patients with CHA2DS2-VASc score=0, or paroxysmal AF without prior stroke or transient ischemic attack, had LAA thrombi. On univariate analysis, non-paroxysmal AF, structural heart disease, antiplatelet therapy, larger left atrium, higher brain natriuretic peptide (BNP), reduced LAA flow, and higher CHA2DS2-VASc score were all associated with LAA thrombi. On multivariate analysis, BNP ≥173 pg/mL remained the only independent predictor of LAA thrombi.

CONCLUSIONS

LAA thrombi were found in 2.7% of Japanese NVAF patients scheduled for procedures despite ongoing oral anticoagulation therapy. Incidence of thrombi was similar for patients on DOAC and on warfarin.

Characterization of Cerebrovascular Events After Left Atrial Appendage Occlusion

Cardioembolic strokes are generally more lethal and disabling than other source of strokes. Data from PROTECT AF (Watchman Left Atrial Appendage Closure Technology for Embolic Protection in Patients With Atrial Fibrillation) suggest that strokes after left atrial appendage occlusion (LAAO) with the Watchman device are less disabling than those in the warfarin group. No data assessing the severity of strokes after LAAO with the AMPLATZER Cardiac Plug (ACP) are available. The objective of the study was to evaluate the severity of cerebrovascular events after LAAO with the ACP in a population mostly characterized by an absolute or relative contraindication to oral anticoagulation. Data from the ACP multicenter registry were analyzed. Disabling strokes were defined as those with a modified Rankin score of 3 to 6 at 90 days after the event. A total of 1,047 subjects were included. The mean age and CHADS₂ score were 75 ± 8 years and 2.8 ± 1.3, respectively. Procedural success was achieved in 97.3% and 4.9% of the patients presented procedural major adverse events. Clinical follow-up was complete in 98.2% of patients with a median of 13 months. There were 9 strokes (0.9%), 9 transient ischemic attacks (0.9%), and no intracranial hemorrhages (0%) at follow-up. After excluding 2 patients with pre-LAAO disability, functional assessment showed disabling events in 3 (19%) of the remaining 16 patients. The median time of presentation was 420 days (interquartile range 234 to 671) after LAAO, and 17 patients (94%) were on single-antiplatelet therapy when the event occurred. According to our results, cerebrovascular events after LAAO with the ACP system were infrequent and mostly nondisabling.

Optimization Of Stroke Prophylaxis Strategies In Nonvalvular AF -Drugs, Devices Or Both?

Atrial fibrillation (AF) is the most common cardiac arrhythmia with the prevalence increasing over time. AF probably afflicts ≥2% of worldwide adult population and increases with age.[1-3] In the Framingham Heart Study, the lifetime risk of having at least one episode of AF for 40-year-old men and women was 26% and 23% respectively.[4].

Cardiac CT and echocardiographic evaluation of peri-device flow after percutaneous left atrial appendage closure using the AMPLATZER cardiac plug device

OBJECTIVES

The aim of the study was to examine frequency, size, and localization of peri-device leaks after percutaneous left atrial appendage (LAA)-closure with the AMPLATZER-Cardiac-Plug (ACP) by using a multimodal imaging approach, i.e. combined cardiac-CT and TEE follow-up.

BACKGROUND

Catheter-based LAA-occlusion using ACP aims to reduce the risk of stroke in patients with atrial fibrillation. Detection of peri-device leaks after ACP implantation by TEE is challenging, the few available data are inconsistent and the frequency of LAA leaks after ACP implantation remains therefore unclear.

METHODS

Cardiac-CT using a multi-phase protocol and a second-generation dual-source-CT-system was performed in 24 patients with non-valvular atrial fibrillation starting 3 months after LAA-closure by ACP. Color Doppler multiplane TEE was used to evaluate peri-device flow.

RESULTS

Cardiac-CT follow-up detected any persistent LAA contrast filling in 62% of patients (n = 15), but leak-sizes were small (1.5 ± 1.4 mm). Peri-device leaks were almost exclusively localized at the posterior portion of the LAA-orifice (>90%). TEE follow-up revealed peri-device flow in 36% of patients (jet-sizes: ≤ 4 mm). ACP-lobe compression (>10%) and perpendicular ACP-lobe orientation to the LAA-neck axis, that was also dependent on LAA anatomy, were substantially more frequent in patients with complete LAA closure.

CONCLUSION

The present study evaluates for the first time peri-device flow after LAA closure by ACP using a combined cardiac-CT and TEE follow-up. Persistent LAA-perfusion was frequently detected, leak-sizes were small and were less frequent when lobe compression was >10% and lobe orientation was perpendicular to the LAA-neck axis, that was also related to the LAA anatomy. The clinical significance of these small leaks after LAA-closure using ACP needs to be further evaluated in future studies.

Left atrial appendage exclusion-Where do we stand?

Atrial fibrillation (AF) is consider to be the most common cardiac arrhythmia with an increasingly prevalence. It is postulated that the source of thromboembolism in 90% of patients with non-valvular AF arises from the left atrial appendage (LAA). Stroke is the most feared and life threatening consequence of thromboembolism. Oral anticoagulation (OAC) with vitamin-K-antagonists is the standard medical therapy for stroke prevention in patients with AF. Unfortunately, chronic therapy with vitamin-K-antagonists is contraindicated in 14% to 44% of patients with AF who are at risk for stroke, and its benefits are limited by underutilization, narrow therapeutic window and increased risk for bleeding, making it often undesired. Therefore, mechanical LAA exclusion is a means of preventing thrombus formation in the appendage and subsequent thromboembolic events in these patients. The LAA can be excluded from the systemic circulation via surgical, percutaneous, or thoracoscopic approaches. Several studies of percutaneous transcatheter delivery of dedicated LAA exclusion devices, such as the percutaneous left atrial appendage transcatheter occlusion (PLAATO) device, Watchman device and the Amplatzer cardiac plug, have shown encouraging results as an alternative to vitamin-K-antagonists therapy for selected patients, good feasibility and efficacy, with a high rate of successful implantation. We discuss the current evidence for LAA exclusion in patients and review their results.

The value of diastolic function parameters in the prediction of left atrial appendage thrombus in patients with nonvalvular atrial fibrillation

BACKGROUND

Left ventricular diastolic impairment and consequently elevated filling pressure may contribute to stasis leading to left atrial appendage thrombus (LAAT) in nonvalvular atrial fibrillation (AF). We investigated whether transthoracic echocardiographic parameters can predict LAAT independent of traditional clinical predictors.

METHODS

We conducted a retrospective cohort study of 297 consecutive nonvalvular AF patients who underwent transthoracic echocardiogram followed by a transesophageal echocardiogram within one year. Multivariate logistic regression analysis models were used to determine factors independently associated with LAAT.

RESULTS

Nineteen subjects (6.4%) were demonstrated to have LAAT by transesophageal echocardiography. These patients had higher mean CHADS2 scores [2.6 ± 1.2 vs. 1.9 ± 1.3, P = 0.009], higher E:e' ratios [16.6 ± 6.1 vs. 12.0 ± 5.4, P = 0.001], and lower mean e' velocities [6.5 ± 2.1 cm/sec vs. 9.1 ± 3.2 cm/sec, P = 0.001]. Both E:e' and e' velocity were associated with LAAT formation independent of the CHADS2 score, warfarin therapy, left ventricular ejection fraction (LVEF), and left atrial volume index (LAVI) [E:e' odds-ratio = 1.14 (95% confidence interval = 1.03 - 1.3), P = 0.009; e' velocity odds-ratio = 0.68 (95% confidence interval = 0.5 - 0.9), P = 0.007]. Similarly, diastolic function parameters were independently associated with spontaneous echo contrast.

CONCLUSION

The diastolic function indices E:e' and e' velocity are independently associated with LAAT in nonvalvular AF patients and may help identify patients at risk for LAAT.

Atrial Fibrillation - A Common Ground for Neurology and Cardiology

Atrial fibrillation (AF) has a huge impact on clinical stroke because it is the primary cause of cardio-embolism, which constitutes ~20% of all strokes. As a result, there is a great need to explore safer and more effective primary and secondary prophylactic agents. In this article, we discuss the overlapping issues pertaining to AF from both a neurology and cardiology standpoint. We focus on the dynamic interplay of neurovascular and cardiovascular diseases in relation to AF, traditional and novel risk factors for AF leading to stroke, impact of AF on cognitive decline, and current upstream medical and surgical options for embolism prophylaxis.

Role of video-assisted thoracoscopy in the management of stroke

OBJECTIVE

To evaluate the role of surgery (anterior thoracotomy versus video-assisted thoracoscopy) in avoidance of stroke by obliteration of the left atrial appendage in patients with chronic nonrheumatic atrial fibrillation.

METHODS

In a prospective study, 58 patients (35 men and 23 women, aged 62 ± 13.2 years) with chronic nonrheumatic atrial fibrillation were divided into 2 groups: group A was 29 patients who underwent an anterior thoracotomy, and group B was 29 patients who had video-assisted thoracoscopic obliteration of the left atrial appendage. All patients were followed up for at least 2 years.

RESULTS

The 2 groups were well matched for age, sex, and comorbidities. No stroke was observed in either group. Operative time was significantly longer in group B. There was no intraoperative or postoperative complication, except for 2 cases of superficial wound infection in group A.

CONCLUSIONS

In chronic atrial fibrillation, prophylactic left atrial appendage exclusion is suggested to prevent occurrence of stroke, which can be achieved by a surgical or thoracoscopic approach, but a video-assisted thoracoscopic approach is effective, less invasive, and avoids the complications of a surgical approach.

Evidence-based percutaneous closure of the left atrial appendage in patients with atrial fibrillation

Atrial fibrillation is the most common cardiac arrhythmia, and its prevalence is increasing. Cardioembolic stroke, most of the times secondary to thrombus formation in the left atrial appendage, is its most feared and life threatening consequence. Oral anticoagulation with vitamin-K-antagonists is currently the most used prophylaxis for stroke in patients with atrial fibrillation; unfortunately, its benefits are limited by a narrow therapeutic window and an increased risk for bleeding, making it often undesired. Percutaneous occlusion of the left atrial appendage is a novel alternative strategy for cardioembolic stroke prophylaxis in patients with atrial fibrillation at a high risk of stroke but with contraindication for long-term oral anticoagulation therapy. At present, several devices have been developed specifically for percutaneous occlusion of the left atrial appendage. Current results show good feasibility and efficacy for these devices, with a high rate of successful implantation, although also associated with the inherent potential periprocedural complications. This work reviews the current state of the art of percutaneous left atrial appendage closure for stroke prophylaxis in patients with atrial fibrillation.

Surgical strategies and devices for surgical exclusion of the left atrial appendage: a word of caution

In patients with chronic atrial fibrillation, 90% of clots are located in the left atrial appendage (LAA). Therefore, LAA exclusion is a means of preventing thrombus formation and subsequent thromboembolic events in these patients. The LAA can be excluded from the systemic circulation via surgical, percutaneous, or thoracoscopic approaches. The surgical aim is complete obliteration of the appendage without a significant increase in either postoperative complications (bleeding, arrhythmias) or recurrence. We discuss the current surgical techniques available for LAA obliteration and review their results.

[Percutaneous exclusion of the left atrial appendage: perspectives]

With its high prevalence and well-known thromboembolic risk, atrial fibrillation (AF) is a crucial component of the 2010-2014 actions plan, ongoing in France to reduce the annual incidence of stroke. The stroke risk is stratified well with the CHA(2)DS(2)-VASc score. With the current guidelines, most patients with AF should be on oral anticoagulant regimen, a treatment recognized as effective but whose bleeding risks limit its use. In clinical practice, warfarin is often not prescribed in patients with high risk of stroke. Thus, the exploration of new ways in preventing thromboembolic events in patients with AF is needed. Beside new more convenient anticoagulant agents, the exclusion of the left atrial appendage recognized as main source of thrombi, may be an alternative in patients with both high risk of thrombotic and haemorrhagic events. Surgical experience showed that the results depend on the quality of the exclusion. For over the past 10 years, several percutaneous exclusion systems of the left atrial appendage have been developed. A randomized study (PROTECT AF) demonstrated the non-inferiority of the percutaneous exclusion in comparison with the warfarin. However, the place of this interventional therapy remains to be clarified, particularly the definition of the target population. This often multidisciplinary approach will have to be accompanied by a reduction of periprocedural complications, increase in rate of complete occlusion, and enough long clinical follow-up to assess the efficiency of this strategy.

Role for the left atrial appendage occlusion device in managing thromboembolic risk in atrial fibrillation

Only 50% of patients who would benefit from warfarin therapy for atrial fibrillation (AF) receive treatment because of clinical concerns regarding chronic anti-coagulation. Percutaneous strategies to treat AF, including pulmonary vein isolation with a curative intent or atrioventricular nodal ablation and implantation of a permanent pacemaker for palliative rate control, have not eliminated the need to manage thromboembolic risk. With the development of a percutaneous left atrial appendage (LAA) occlusion device (the WATCHMAN percutaneous left atrial appendage occluder - Atritech Inc., Plymouth, MN, USA) for thromboembolic protection in non-valvular AF a significant therapeutic option for select patients may be available. We present the first case performed in Australia (24 November 2009) and explore this new methodology.

Evaluation of the left atrial appendage with real-time 3-dimensional transesophageal echocardiography: implications for catheter-based left atrial appendage closure

BACKGROUND

Precise knowledge of left atrial appendage (LAA) orifice size is crucial for correct sizing of LAA closure devices. The aim of the present study was to determine the performance of real-time 3D transesophageal echocardiography (RT3DTEE) for LAA orifice size assessment, compared with 2D transesophageal echocardiography (2DTEE), and to investigate the impact of atrial fibrillation (AF) on LAA orifice size.

METHODS AND RESULTS

One hundred thirty-seven patients (38 control subjects, 31 with paroxysmal AF, 38 with persistent AF and 30 with permanent AF) underwent 2DTEE and RT3DTEE. Both techniques were used to measure LAA orifice area. Clinically-indicated 64-slice computed tomography (CT) was used as reference technique in 46 patients. Two-dimensional TEE underestimated LAA orifice area, compared with RT3DTEE (1.99±0.94 cm(2) versus 3.05±1.27 cm(2); P<0.001). RT3DTEE showed higher correlation with CT for the assessment of LAA orifice area, compared with 2DTEE (r=0.92; 95% confidence interval, 0.85 to 0.95, versus r=0.72; 95% confidence interval, 0.54 to 0.83, respectively). At Bland-Altman analysis, RT3DTEE and 2DTEE underestimated LAA orifice area, compared with CT. However, RT3DTEE showed smaller bias (0.07 cm(2) versus 0.72 cm(2)) and narrower limits of agreement (-0.71 to 0.85 cm(2) versus -0.58 to 2.02 cm(2)) with CT, compared with 2DTEE. Among AF patients, a progressive increase in RT3DTEE-derived LAA orifice area was observed with increasing frequency of AF (P<0.001). At multivariate analysis, AF and left atrial volume index (P<0.001 for both) were independently associated with RT3DTEE-derived LAA orifice area.

CONCLUSIONS

RT3DTEE is more accurate than 2DTEE for the assessment of LAA orifice size. A progressive increase in LAA orifice area is observed with increasing frequency of AF.

Left atrial appendage closure

Stroke prevention is the primary goal in atrial fibrillation (AF) given its clinical and socioeconomic impact. With AF, the prevalence of thromboembolic stroke continues to rise and there is an urgent need to develop better strategies of stroke prevention. Warfarin, although effective when used appropriately, is burdened by underutilization, narrow therapeutic windows, and life-threatening bleeding complications. Novel pharmacologic agents have been plagued by off-target toxicity and only modest improvement in bleeding complications over warfarin. Because most thromboemboli arise from the left atrial appendage (LAA), surgical exclusion of the LAA is often used in AF patients undergoing cardiac surgery. Percutaneous device LAA closure has now been developed as an adjunct and as an alternative to pharmacotherapy in patients with AF. Promising randomized data are available with the WATCHMAN device, while several other devices are in various stages of clinical and preclinical development.

The CHADS score role in managing anticoagulation after surgical ablation for atrial fibrillation

BACKGROUND

Managing anticoagulation after surgical ablation is challenging, especially when sinus rhythm has been restored and the left atrial appendage has been surgically managed. The study purpose was to examine the applicability of the CHADS(2) in determining anticoagulation strategies after surgical ablation. CHADS(2) is a scoring system (0 to 6) used to indicate a patient's risk for a thromboembolic stroke and used for anticoagulation strategies. One point is given for any of the following conditions: C, congestive heart failure; H, hypertension; A, age 75 years old or greater; D, diabetes mellitus; and S, stroke which receives 2 points. A score of 2 or greater is an indication for a patient to be placed on warfarin unless otherwise contraindicated.

METHODS

A prospective, longitudinally designed study where CHADS(2) was calculated for all patients (n = 385). Clinical data on rhythm, anticoagulation medication, bleeding, and embolic stroke-transient ischemic attack (TIA) was obtained every 3 months. Logistic regression models were used to determine significant predictors of either event.

RESULTS

Of the 385 patients, 17% presented with a history of stroke-TIA. In a mean follow-up of 32.77 ± 16.33 months, embolic stroke-TIA events occurred in 4 patients (4.2 first events per 1,000 patient years) and bleeding events occurred in 69 patients (72.8 first events per 1,000 patient years). There was no significant difference in mean CHADS(2) between the stroke event and nonevent group (0.75 vs 1.46, respectively; p = 0.21), but there was a significant difference in CHADS(2) between the major bleed event group and the nonevent group (2.31 vs 1.41, respectively; p < 0.003). The logistic regression model was not predictive of stroke-TIA, but was significantly predictive of bleeding events (χ(2) = 10.30, p < 0.02).

CONCLUSIONS

The number of thromboembolic events after surgical ablation procedure is low and appears unrelated to the CHADS(2). This, together with the higher rate of bleeding, raises questions regarding the applicability of the CHADS(2) for patients after surgical ablation. A randomized study is required to define the risks and anticoagulation strategies for patients after surgical ablation.