Assessment of left atrial appendage function by biplane transesophageal echocardiography in patients with nonrheumatic atrial fibrillation: identification of a subgroup of patients at increased embolic risk

Structural Comparison between the Right and Left Atrial Appendages Using Multidetector Computed Tomography

The three-dimensional (3D) structures of the right atrial appendage (RAA) and left atrial appendage (LAA) were compared to clarify why thrombus formation less frequently occurs in RAA than in LAA. Morphological differences between RAA and LAA of 34 formalin-preserved cadaver hearts were investigated. Molds of RAA and LAA specimens were made and the neck areas, volumes of the atrial appendages (AA), and amount of pectinate muscles (PMs) were analyzed using multidetector computed tomography. In RAA, most PMs were connected to one another and formed a “dendritic” appearance and the inner surface area was smaller than in LAA. RAA had smaller volumes and larger neck areas than LAA. The ratios of the neck area/volume were larger and the amounts of PMs were smaller in RAA than in LAA. The volumes, neck areas, and amount of PMs of RAA were significantly correlated with those of LAA. According to the 3D structure, RAA appears to be suited for a more favorable blood flow, which may explain why the thrombus formation is less common in RAA than in LAA. Examining not only LAA but also RAA by transesophageal echocardiography may be useful in high-risk patients of thrombus formation in LAA because the volume, neck area, and amount of PMs of LAA reflect the shape of RAA.

The use of imaging in new transcatheter interventions: an EACVI review paper

Transcatheter therapies for the treatment of valve heart diseases have expanded dramatically over the last years. The new developments and improvements in devices and techniques, along with the increasing expertise of operators, have turned the catheter-based approaches for valvular disease into an established treatment option. Various imaging techniques are used during these procedures, but echocardiography plays an essential role during patient selection, intra-procedural monitoring, and post-procedure follow-up. The echocardiographic assessment of patients undergoing transcatheter interventions places demands on echocardiographers that differ from those of the routine evaluation of patients with valve disease, and there is a need for specific expertise for those working in the cath lab. In the context of the current rapid developments and growing use of transcatheter valve therapies, this document intends to update the previous recommendations and address new advancements in imaging, particularly for those involved in any stage of the treatment of patients with valvular heart diseases.

The Mechanism of and Preventive Therapy for Stroke in Patients with Atrial Fibrillation

Atrial fibrillation is a major cardiac cause of stroke, and a pathogenesis involving thrombus formation in patients with atrial fibrillation is well established. A strategy for rhythm control that involves catheter ablation and anticoagulation therapy is evolving. A strategy for rhythm control that restores and maintains sinus rhythm should reduce the risk of ischemic stroke that is associated with atrial fibrillation; however, this is yet to be proven in large-scale randomized controlled trials. This paper reviews the emerging role of rhythm control therapy for atrial fibrillation to prevent stroke.

Unexpectedly High Incidence of Stroke and Left Atrial Appendage Thrombus Formation After Electrical Isolation of the Left Atrial Appendage for the Treatment of Atrial Tachyarrhythmias

Background—

Electric left atrial appendage (LAA) isolation (LAAI) may occur during catheter ablation of atrial tachyarrhythmias. Data regarding the risk of thromboembolic events and stroke after LAAI are sparse. This study evaluated the incidence of LAA thrombus formation and thromboembolic events after LAAI.

Methods and Results—

Fifty patients had LAAI (age=71 years; female=56%; CHA 2 DS 2 -VASc score before ablation =3 [2;3]). LAAI patients were compared with matched patients with comparable baseline characteristics who underwent atrial fibrillation ablation without LAAI (n=50). Ablation strategies in the LAAI group included pulmonary vein isolation in 50 (100%), left atrial isthmus line in 47 (94%), anterior line in 45 (90%), complex atrial fractionated potentials in 24 (48%), and roofline in 14 (28%) patients. Transesophageal echocardiography was performed during follow-up in 47/50 (94%) patients in the LAAI group and in all patients of the control group. Oral anticoagulation (OAC) independent of CHA 2 DS 2 -VASc score was strongly recommended in all patients. During a median follow-up of 6.5 (4–12) months, stroke occurred in 2 patients on OAC and transient ischemic attack in one without OAC in the LAAI group. In the remaining 47 patients, LAA thrombus was identified on transesophageal echocardiography in 10 (21%) patients (OAC=9; no OAC=1). In the control group, no LAA thrombus was detected and no stroke occurred ( P <0.001). Stable sinus rhythm was maintained in 32 patients (64%) of the LAAI group after a median follow-up of 6.5 months (4–12), including 17/32 patients on antiarrhythmic drugs.

Conclusions—

After LAAI, an unexpectedly high incidence of LAA thrombus formation and stroke was observed despite OAC therapy.

Use of Heparin in Acute Ischemic Stroke: Is There Still a Role?

Heparin has long been a contested therapy in acute ischemic stroke (AIS). In current practice, heparin is considered on a case-by-case basis, but there is no consensus as to the appropriate timing of anticoagulation or for which ischemic stroke subtypes heparin may be beneficial. To provide better clarity on this issue, we review current research focusing on the use of heparin in AIS in each stroke subtype and subsequently make recommendations to provide readers with a systematic approach to managing complex stroke patients for which acute anticoagulation may be valuable. We conclude that there are certain subpopulations of ischemic stroke patients that may derive benefit from heparin when given acutely, including patients with symptomatic large artery stenosis >70 %, non-occlusive intraluminal thrombus, and in patients with high-risk cardiac conditions including left ventricular thrombus, left ventricular assist devices, and mechanical heart valves.

Transesophageal Echocardiography in Atrial Fibrillation

Transesophageal echocardiography (TEE) plays an important role in atrial fibrillation (AF), mainly to detect the presence of left atrial appendage (LAA) thrombus. It is useful in direct current cardioversion (DCC) guidance and for AF ablation and LAA occlusion. With the increasing number of patients affected by AF, the use of TEE will grow and become an important screening modality for LAA thrombus. Future direction includes broader multi-institutional use; further tools to risk stratify patients; and the use of a new spectrum of oral anticoagulants and their cost-effectiveness in patients with AF undergoing DCC, AF ablation, and LAA occlusion.

Left Atrial Remodeling Assessed by Transthoracic Echocardiography Predicts Left Atrial Appendage Flow Velocity in Patients With Paroxysmal Atrial Fibrillation

Atrial fibrillation (AF) is associated with an increased risk of stroke and other thromboembolic events. Left atrial (LA) thrombus formation is closely related to LA dysfunction, particularly to decreased LA appendage flow velocity (LAA-FV) in patients with AF. We estimated LAA-FV using parameters noninvasively obtained by transthoracic echocardiography (TTE) in patients with paroxysmal AF.Echocardiographic and clinical parameters were assessed in 190 patients with nonvalvular paroxysmal AF showing sinus heart rhythm during transesophageal echocardiography (TEE) and TTE.LAA-FV (60 ± 22 cm/s) significantly correlated with the time interval between the initiation of the P-wave on ECG and that of the A-wave of transmitral flow on TTE (PA-TMF, correlation coefficient, -0.32; P < 0.001), LA dimension (LAD, -0.31; P < 0.001), septal a' velocity of tissue Doppler imaging (TDI, 0.35; P < 0.001), E/e' ratio (-0.28, P < 0.001), E velocity of transmitral flow (-0.20, P = 0.008), E/A ratio of transmitral flow (-0.18, P = 0.02), CHA2DS2-VASc score (-0.15, P = 0.04), and BNP plasma level (-0.32, P = 0.002). Multivariate analysis revealed that PA-TMF (standardized partial regression coefficient, -0.17; P = 0.03), a' velocity (0.24, P = 0.004), and LAD (-0.20, P = 0.01) were independent predictors of LAA-FV (multiple correlation coefficient R, 0.44; P < 0.001).Parameters of atrial remodeling, ie, decreased a' velocity, increased LAD, and PA-TMF during sinus rhythm may be useful predictors of LA blood stasis in patients with nonvalvular PAF. LAA-FV can be estimated using these TTE parameters instead of TEE.

Left Atrial Appendage Remodeling After Lariat Left Atrial Appendage Ligation

Background—

Left atrial appendage (LAA) ligation with the Lariat device is being used for stroke prevention in atrial fibrillation. Residual leaks into the LAA are commonly reported after the procedure. Little is known about the anatomic LAA remodeling after Lariat ligation.

Methods and Results—

In an exploratory study, we evaluated LAA 3-dimensional geometry via computed tomographic scan in 31 consecutive patients before Lariat closure and after a minimum of 30 days post procedure. Thirteen patients were classified as unfavorable cases based on anatomic criteria. Our population had an average age of 70±12 years, a mean CHADS2 (congestive heart failure, hypertension, age>75, diabetes mellitus, history of stroke) score of 3.2±1.2, a mean CHADS2VASC (CHADS2 in addition to female sex, ages 65–75, as well as double impact of age >75, vascular disease) of 4.2±1.5, and a mean HASBLED (hypertension, abnormal renal/liver function, stroke, bleeding predisposition/history, labile international normalized ratio, elderly, drugs/alcohol) bleeding score of 4.0±1.1. Successful suture deployment was achieved in all cases, but 3 patients had intraprocedural residual flow into the LAA (leak). On follow-up, 10 patients (32%) had recanalized residual LAA cavities, which were morphologically similar to the original LAA, albeit significantly smaller in volume (22.5±13.3% of the original volume). Recanalization was not associated with age, sex, comorbid conditions, stroke or bleeding risk scores, follow-up interval, baseline LAA volume, or morphology. Unfavorable cases had anatomic outcomes comparable with those of the anatomically favorable population. No patients have exhibited thromboembolism after 842±338 days post ligation.

Conclusions—

Incomplete LAA ligation after Lariat is common. However, the remodeled LAA cavity is dramatically reduced. Diminished cavity size and tightening of the LAA orifice may play a role in the reduction of thrombus formation.

Real-time physiologic biomarker for prediction of atrial fibrillation recurrence, stroke, and mortality after electrical cardioversion: A prospective observational study

BACKGROUND

Left atrial appendage emptying flow velocity (LAAEV) depends largely on left atrioventricular compliance and may play a role in mediating the perpetuation of atrial fibrillation (AF) and AF-related outcomes.

METHODS

We identified 3,251 consecutive patients with sustained AF undergoing first-time successful transesophageal echocardiography (TEE)-guided electrical cardioversion who were enrolled in a prospective registry between May 2000 and March 2012. Left atrial appendage emptying flow velocity was stratified into quartiles: ≤20.2, 20.3-33.9, 34-49.9, and ≥50 cm/s. Multivariate Cox regression models were used to identify independent predictors of AF recurrence, ischemic stroke, and all-cause mortality.

RESULTS

The mean (SD) age was 69 (12.6) years and 67% were men. Compared with the fourth quartile, patients in the first-third quartiles were significantly older, had higher CHA2DS2-VASc (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, stroke/transient ischemic attack [TIA], vascular disease, age 65-74 years, sex category) scores, greater frequency of atrial spontaneous echo contrast, and AF of longer duration. Kaplan-Meier analysis showed a decreased probability of event-free survival with decreasing quartiles of LAAEV. Five-year cumulative event rates across first-fourth quartiles were 83%, 80%, 73%, and 73% (P < .001) for first AF recurrence; 7.5%, 7.0%, 4.1%, and 4.0%, for stroke (P = .01); and 31.3%, 26.1%, 24.1%, and 19.4%, for mortality (P < .001), respectively. Multivariate Cox regression analysis revealed an independent association of the first and second quartiles with AF recurrence (P < .001 and P < .001, respectively) and stroke (P = .03, and P = .04, respectively), and of the first quartile with mortality (P = .003).

CONCLUSIONS

Patients with decreased LAAEV have an increased risk of AF recurrence, stroke, and mortality after successful electrical cardioversion. Real-time measurement of LAAEV by TEE may be a useful physiologic biomarker for individualizing treatment decisions in patients with AF.

Assessment of normal left atrial appendage anatomy and function over gender and ages by dynamic cardiac CT

OBJECTIVES

The aim of this study was to evaluate variations in anatomy and function according to age and gender using cardiac computed tomography (CT) in a large prospective cohort of healthy patients.

BACKGROUND

The left atrial appendage (LAA) is considered the most frequent site of intracardiac thrombus formation. However, variations in normal in vivo anatomy and function according to age and gender remain largely unknown.

METHODS

Three-dimensional (3D) cardiac reconstructions of the LAA were performed from CT scans of 193 consecutive patients. Parameters measured included LAA number of lobes, anatomical position of the LAA tip, angulation measured between the proximal and distal portions, minimum (iVolmin) and maximum (iVolmax) volumes indexed to body surface area (BSA), and ejection fraction (LAAEF). Relationship with age was assessed for each parameter.

RESULTS

We found that men had longer and wider LAAs. The iVolmin and iVolmax increased by 0.23 and 0.19 ml per decade, respectively, while LAAEF decreased by 2% per decade in both sexes.

CONCLUSIONS

Although LAA volumes increase, LAAEF decreases with age in both sexes.

KEY POINTS

• Variations in normal left atrial appendage in vivo anatomy and function remain largely unknown. • Cardiac CT is reliable for left atrial appendage volume measurements. • Although LAA volumes increase, LAAEF decreases with age in both sexes.

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

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

Predictive Value of D-Dimer Levels and Tissue Doppler Mitral Annular Systolic Velocity for Detection of Left Atrial Appendage Thrombus in Patients with Mitral Stenosis in Sinus Rhythm

BACKGROUND

Transesophageal echocardiogram (TEE) is a gold standard test for diagnosis of left atrial (LA) thrombus, but it has limited sensitivity for identification of small thrombi within side lobes. Thus, the absence of visualizing a left atrial appendage (LAA) thrombus does not equate with the absence of a LAA thrombus.

AIM

To assess the predictive value of mitral annular systolic velocity (Sa) and D-dimer for the detection of LA thrombus and spontaneous echocardiographic contrast (SEC) in mitral stenosis (MS) patients with sinus rhythm (SR).

METHODS

Transthoracic echocardiogram, TEE, and D-dimer analysis were performed in 104 severe MS patients and divided them into three groups: Group I:no LA thrombus or SEC; Group II:LA SEC only; and Group III:LA thrombus.

RESULTS

Group III had more severe New York Heart Association (NYHA) class (III-IV) dyspnea and lower Sa (6.9 ± 0.7 vs.10.0 ± 1.2 cm/sec), lower LAA late emptying velocity (17.7 ± 2.1 vs. 24.4 ± 4.2 cm/sec), larger LA transverse dimension, and LAA area (LAAA) than group I+II. Mean D-dimer levels were higher in groups III and II than in group I. In multivariate analysis Sa, D-dimer levels, LAAA, and NYHA class were independent predictors of LA thrombus. ROC curve analysis revealed that higher Sa >8 cm/sec and lower D-dimer levels <370 μg/L predict the absence of LA thrombus and lower Sa <8 cm/sec and higher D-dimer levels >510 μg/L predict the presence of LA thrombus.

CONCLUSION

Measurement of Sa and D-dimer levels is necessary for better assessment of LA thrombus and SEC, for identification of patients who are at high risk for LA thrombus formation and for initiation of prophylactic anticoagulation.

Association between left atrial appendage morphology evaluated by trans-esophageal echocardiography and ischemic cerebral stroke in patients with atrial fibrillation

The left atrial appendage (LAA) represents one of the major sources of cardiac thrombi responsible for embolic stroke in patients with atrial fibrillation (AF). The aim of the present study was to evaluate LAA structure and functions by transesophageal echocardiography (TEE) in patients with AF to investigate the possible association between the different LAA morphologies and the patients' history of ischemic cerebral stroke. We included 50 patients with non-valvular AF (29 chronic, 21 paroxysmal), 24 patients (13 men) without stroke; and 26 patients (9 men) with a history of ischemic stroke. All patients underwent TEE evaluation of LAA morphology and functions. Compared to patients without stroke, patients with ischemic stroke had significantly higher CHADS2 scores (4.19 ± 0.89 versus 1.67 ± 1.13; P < 0.001) and C-reactive protein levels (8.3 ± 1.6 versus 7.6 ± 0.83 mg/L; P = 0.023), and lower peak filling (21.7 ± 11.3 versus 31.2 ± 9.5 cm/second; P = 0.033) and emptying (22.2 ± 9.7 versus 33.4 ± 13.4 cm/second, P = 0.030) velocities. Triangular LAA morphology had a higher prevalence in patients with stroke (36% versus 12% in non-stroke group); and in half of them an LAA thrombus was present. LAA thrombi were detected in 9 patients (18%) with stroke and in 5 patients (10%) without stroke. On multivariate logistic regression analysis, age (OR = 1.202 [1.042-1.585]; P = 0.041), LAA orifice diameter (OR = 1.275 [1.102-1.748]; P = 0.028), and triangular LAA morphology (OR = 4.53 [1.629-8.381]; P = 0.011) were significantly and independently associated with ischemic stroke in AF patients. LAA morphology evaluated by TEE may be useful for predicting ischemic cerebral stroke in patients with non-valvular AF, especially in those with a low CHADS2 score.

Techniques To Improve Left Atrial Appendage Imaging

The clinical importance of the left atrial appendage (LAA) is increasingly recognized. The assessment of the unique anatomy and function of the LAA is especially important in the setting of atrial fibrillation (AF). AF is the most commonly occurring cardiac arrhythmia, and the association of LAA thrombi and AF has been well established. Transesophageal echocardiography (TEE) is a widely available imaging tool to exclude the potential presence of LAA thrombus prior to cardioversion in patients with AF. Commercially available products containing microbubbles to enhance ultrasound images, termed "ultrasound contrast agents" (UCA) are indicated for use with transthoracic echocardiography to improve cardiac structure and function assessment, but can also be used with TEE as an adjunctive tool to assess the LAA. Integrative multimodality imaging techniques can be used in evaluation of the LAA as indicated in various clinical scenarios including: stroke risk assessment, decision-making prior to cardioversion in AF, placement and assessment percutaneous transcatheter LAA occlusion procedures, and assessment of results of procedural or surgical exclusion of LAA. In this article, various imaging techniques that are available for non-invasive visualization of the LAA will be reviewed along with the clinical importance of assessment of LAA anatomy and function.

Occult left atrial ball-like thrombus in a patient referred for surgical removal of suspected cerebellum tumor

BACKGROUND

Atrial fibrillation and related cardio-embolic cerebrovascular accidents are two well-defined major healthcare problems worldwide. It has been approximated that 2.2 million people in America and 4.5 million in European Union have paroxysmal or persistent atrial fibrillation. And atrial fibrillation itself is an independent long-term risk factor of stroke. We present a case of patient referred to our center for surgical removal of suspected cerebellum tumor, a case that had a rather unexpected ending.

CASE REPORT

A 58-year-old male patient with a history of atrial fibrillation, congestive heart failure (NYHA II/III), stable coronary artery disease, diabetes type 2 and hyperlipidemia presented with vertigo, headaches, mainly during physical activity and increased tiredness. Performed computer tomography revealed two lesions in the cerebellum and in the left lateral chamber. The diagnosis of a proliferative disease of the cerebellum was established and patient was referred to the Neurosurgical Department. Fortunately, before the operation the echocardiography was performed, which revealed two lesions in left atrium. The decision of the Heart Team was to refer the patient for an open-heart surgery, in which two thrombi were removed. Neurosurgeons decided to withdraw from further surgery and proceed with head MRI and conservative treatment, deciding that the lesion in the cerebellum was most likely an ischemic area.

CONCLUSIONS

Looking at the brain lesion should always be done from the whole patient's perspective. And using mutlimodality imaging may lead to appropriate diagnosis, correct course of therapeutic action and unexpected ending of a rather non-extraordinary case.

Impact of increased orifice size and decreased flow velocity of left atrial appendage on stroke in nonvalvular atrial fibrillation

The structural and functional characteristics of left atrial appendage (LAA) in patients with atrial fibrillation (AF) with previous stroke remain incompletely elucidated. This study investigated whether a larger LAA orifice is related to decreased LAA flow velocity and stroke in nonvalvular AF. The dimension, morphology, and flow velocity of LAA were compared in patients with nonvalvular AF with (stroke group, n = 67, mean age 66 ± 9 years) and without ischemic stroke (no-stroke group, n = 151, mean age 56 ± 10 years). Compared with no-stroke group, the stroke group had larger LA dimension (4.7 ± 0.8 vs 4.2 ± 0.6 cm, p <0.001), larger LAA orifice area (4.5 ± 1.5 vs 3.0 ± 1.1 cm(2), p <0.001), and slower LAA flow velocity (36 ± 19 vs 55 ± 20 cm/s, p <0.001). LAA flow velocity was negatively correlated with LAA orifice size (R = -0.48, p <0.001). After adjustment for multiple potential confounding factors including CHA2DS2-VASc score, persistent AF, and LA dimension, large LAA orifice area (odds ratio 6.16, 95% confidence interval 2.67 to 14.18, p <0.001) and slow LAA velocity (odds ratio 3.59, 95% confidence interval 1.42 to 9.08, p = 0.007) were found to be significant risk factors of stroke. In patients with LAA flow velocity <37.0 cm/s, patients with large LAA orifice (>3.5 cm(2)) had greater incidence of stroke than those with LAA orifice of ≤3.5 cm(2) (75% vs 23%, p <0.001). In conclusion, LAA orifice enlargement was related to stroke risk in patients with nonvalvular AF even after adjustment for other risk factors, and it could be the cause of decreased flow velocity in LAA.

Complex Left Atrial Appendage Morphology and Left Atrial Appendage Thrombus Formation in Patients With Atrial Fibrillation

Background—

In patients with atrial fibrillation (AF), most thrombus forms in the left atrial appendage (LAA). However, the relation of LAA morphology with LAA thrombus is unknown.

Methods and Results—

We prospectively enrolled 633 consecutive patients who were candidates for catheter ablation for symptomatic drug-resistant AF. Transesophageal echocardiography (TEE) was performed to assess LAA thrombus. LAA structure was assessed by 3-dimensional TEE. LAA orifice area, depth, volume, and number of lobes were measured on reconstructed 3-dimensional images. Clinical characteristics and echocardiographic measures were compared to determine variables predicting LAA thrombus. Excluded were 69 (10.9%) patients who met the exclusion criteria. Finally, this study comprised 564 patients, of whom LAA thrombus was observed in 36 (6.4%) patients. Multivariate analysis revealed CHADS 2 (Congestive heart failure, Hypertension Age>75, Diabetes mellitus and prior Stroke or transient ischemic attack) score ( P =0.002), left ventricular ejection fraction ( P =0.01), degree of spontaneous echo contrast ( P =0.02), left atrial volume ( P =0.02), and number of LAA lobes ( P <0.001) to be independently associated with thrombus formation. Most patients with LAA thrombus (32/34, 94.4%) had ≥3 LAA lobes, whereas LAA thrombus was observed in only 2 (0.7%) of 296 patients with 1 or 2 lobes. LAA volume significantly decreased in patients maintaining sinus rhythm after catheter ablation ( P =0.0009). Number of LAA lobes did not change in any patient.

Conclusions—

Complex LAA morphology characterized by an increased number of LAA lobes was associated with the presence of LAA thrombus independently of clinical risk and blood stasis. This study suggests that LAA morphology might be a congenital risk factor for LAA thrombus formation in patients with AF.

Association between paroxysmal atrial fibrillation and the left atrial appendage ejection fraction during sinus rhythm in the acute stage of stroke: a transesophageal echocardiographic study

BACKGROUND

This study aimed to investigate whether left atrial appendage (LAA) dysfunction evaluated by transesophageal echocardiography (TEE) during sinus rhythm is predictable of paroxysmal atrial fibrillation (PAF) as an embolic source in the acute stage of stroke.

METHODS AND RESULTS

We measured and analyzed LAA flow velocity (LAA-FV) and LAA ejection fraction (LAA-EF) in 300 acute ischemic stroke patients by TEE. We divided the acute ischemic stroke patients into 3 groups. The atrial fibrillation (AF) group (n=58) comprised patients whose TEE was performed during AF rhythm. The PAF group (n=42) comprised patients with a history of AF but with normal sinus rhythm when TEE was performed. The normal sinus (sinus) group (n=200) did not have any history of AF. We found that mean LAA-FV and LAA-EF values in the PAF group were significantly lower than those in the sinus group (P<.001). The diagnostic accuracy of LAA-FV for the diagnosis of PAF calculated as the area under receiver operating characteristic curves was low (.582, 95% confidence interval [CI]=.498-.665) but that of LAA-EF was modest (.721, 95% CI=.653-.789), with an optimal cutoff point of 49.1%.

CONCLUSIONS

LAA dysfunction as determined by TEE (LAA-EF<49.1%) in the acute stage of stroke is predictive of PAF with moderate accuracy. Long-term electrocardiographic monitoring is recommended for cryptogenic stroke patients with LAA dysfunction.

Motion of left atrial appendage as a determinant of thrombus formation in patients with a low CHADS2 score receiving warfarin for persistent nonvalvular atrial fibrillation

BACKGROUND

The aim of this study was to define the independent determinants of left atrial appendage (LAA) thrombus among various echocardiographic parameters measured by Velocity Vector Imaging (VVI) in patients with nonvalvular atrial fibrillation (AF) receiving warfarin, particularly in patients with a low CHADS2 score.

METHODS

LAA emptying fraction (EF) and LAA peak longitudinal strain were measured by VVI using transesophageal echocardiography in 260 consecutive patients with nonvalvular persistent AF receiving warfarin. The patients were divided into two groups according to the presence (n=43) or absence (n=217) of LAA thrombus. Moreover, the patients within each group were further divided into subgroups according to a CHADS2 score ≤1.

RESULTS

Multivariate logistic regression analysis showed that LAAEF was an independent determinant of LAA thrombus in the subgroup of 140 with a low CHADS2 score. Receiver operating characteristics curve analysis showed that an LAAEF of 21% was the optimal cutoff value for predicting LAA thrombus.

CONCLUSIONS

LAA thrombus formation depended on LAA contractility. AF patients with reduced LAA contractile fraction (LAAEF ≤21%) require strong anticoagulant therapy to avoid thromboembolic events regardless of a low CHADS2 score (≤1).

Atrial Fibrillation and the Role of LAA in Pathophysiology and Clinical Outcomes?

Left atrial appendage (LAA) is a source of thromboembolism especially in patients with non valvular atrial fibrillation (AF). It is reasonable to accept LAA as a distinct part of left atrium (LA) with unique anatomical and physiological properties. Advances in imaging modalities increased the knowledge about anatomical and physiological characteristics of LAA. It is important to prevent the AF patients from systemic thromboembolic events, and new pharmacological and non pharmacological management approaches demonstrate encouraging results. Also pulmonary vein isolation which has been accepted as a curative and useful treatment option for the treatment of drug resistant AF has been helpful in understanding the electrophysiological properties of LAA. Accumulating data revealed that LAA continues to be the one of the most important structure of heart during AF because of its distinctive anatomical, mechanical, and electrophysiological properties.

Left atrial appendage closure: a percutaneous transcatheter approach for stroke prevention in atrial fibrillation

Atrial fibrillation is a frequent cause of stroke; in the elderly, more than 20% of strokes are attributed to this common arrhythmia. Anticoagulation with warfarin reduces the risk of stroke by ∼60%; however, a large proportion of patients with atrial fibrillation do not receive this treatment because of relative/absolute contraindications. Moreover, patients often discontinue warfarin for a variety of reasons and chronic warfarin administration rates remain suboptimal. Although the compliance with anticoagulation may improve with novel anticoagulants and bleeding risk can be somewhat reduced when compared with warfarin, there is still a progressive increase in bleeding complications over time. Accordingly, new approaches for stroke prevention in these patients are being explored and tested. In transoesophageal echocardiographic (TEE) studies, more than 90% of thrombi were found in the left atrial appendage (LAA) in non-valvular atrial fibrillation, and transcatheter LAA closure is developed and examined as a novel approach to reduce the risk of stroke in these patients. The PROTECT-AF study provides first evidence from a randomized clinical trial that a strategy of LAA occlusion using the Watchman device can be non-inferior to anticoagulation with warfarin for a combined endpoint in patients with non-valvular atrial fibrillation (mean CHADS(2) score 1.8). In successfully occluded patients fulfilling TEE criteria (86%), warfarin was stopped after 45 days, followed by aspirin and clopidogrel for 6 months after randomization and subsequently aspirin. The PREVAIL trial is further evaluating this concept. Limited data are available for another LAA occlusion system, the Amplatzer Cardiac Plug (ACP) device, for which the ACP trial has been initiated. Left atrial appendage occlusion needs to be performed with meticulous care by experienced operators because periprocedural complications such as pericardial effusion or stroke have been documented. With increased operator experience and technical improvements of the device, these complications can be minimized.

Differences in diffusion-weighted image and transesophageal echocardiographical findings in cardiogenic, paradoxical and aortogenic brain embolism

BACKGROUND AND PURPOSE

The purpose of the present study was to clarify the difference in the infarct topography on diffusion-weighted image (DWI) and cardiac and aortic findings on transesophageal echocardiography (TEE) in stroke patients with different embolic sources.

METHODS

We studied 270 consecutive patients with acute ischemic stroke who had DWI-documented cortical or subcortical infarcts without significant stenosis of the cerebral arteries. As embolic sources, cardiac diseases, right-to-left shunt diseases and an aortic arch atheroma ≥4.0 mm in thickness were identified using various diagnostic tools including TEE.

RESULTS

Seventy-eight (29%) patients had multiple embolic sources. Large infarcts were common in patients in whom cardiac disease was the only embolic source and uncommon in patients in whom aortic atheroma was the only embolic source (p < 0.0001). Vertebrobasilar infarcts were relatively common in patients only having aortic atheromas. Atrial septal aneurysms were more common in patients with a right-to-left shunt than in those with a shunt plus other embolic sources (p = 0.0036). Unique characteristics of the arch atheroma (mobile plaque, extension to branches, or ulcer formation; p < 0.0001) as well as small or moderate-sized infarcts (p = 0.0004) were more common in patients with arch atheromas as the only embolic source than in those with atheromas plus other embolic sources.

CONCLUSIONS

Embolic stroke patients often have multiple embolic sources. The present study suggests the possibility that embolic stroke has unique clinical features depending on its source. DWI and TEE findings might be helpful in characterizing cardiogenic, paradoxical and aortogenic brain embolism.

Left atrial and left atrial appendage systolic function in patients with post-myocardial distal blocks

INTRODUCTION

The study aimed to evaluate function of the left atrium (LA) and of the left atrial appendage (LAA) after myocardial infarction (MI) complicated by intracardiac conduction disturbances.

MATERIAL AND METHODS

The study comprised 59 patients with persistent post-myocardial distal blocks, who were allocated to one of the three following subgroups: study group I - 20 patients with left bundle branch block (LBBB); study group II - 20 patients with right bundle branch block (RBBB), and study group III -19 pts with left anterior hemiblock (LAHB). The control groups included patients with MI in their history and no BBBs (19 pts - group IV) and clinically healthy people (16 patients - group V). The parameters of LA and LAA systolic function were determined by means of transthoracic (TTE) and transoesophageal echocardiography (TOE).

RESULTS

We showed that patients who experienced myocardial infarction not complicated with conduction disturbances expressed compensatory LA systolic function enhancement. In patients with post-myocardial RBBB and LAHB significant enhancement of LA systolic function was observed as well but it was expressed to a lesser degree. There was also a tendency towards deterioration of LA systolic function in patients with post-myocardial LBBB. LBBB did not affect LAA systolic function negatively.

CONCLUSIONS

Parameters of LAA systolic function showed its enhancement in all patients after myocardial infarction irrespective of whether it was complicated by conduction disturbances.

Right atrial appendage function in different etiologies of permanent atrial fibrillation: a transesophageal echocardiography and tissue Doppler imaging study

OBJECTIVES

Several studies exist on the left atrial appendage function (LAA) in permanent atrial fibrillation (AF). However, knowledge about the right atrial appendage (RAA) function is limited. We investigated RAA function with TEE and tissue Doppler imaging (TDI) in permanent AF patients with different etiologies and evaluated predictive parameters of right atrial spontaneous echo contrast (SEC) and thrombi.

METHODS

Patients with permanent AF developed due to three different etiologies (20 mitral stenosis, 44 hypertension, 20 hyperthyroidism) and 23 subjects with sinus rhythm were included into the study. RAA was examined with TEE and pulsed-wave and TDI velocities of RAA were measured.

RESULTS

Both PW-Doppler and TDI velocities were significantly impaired in all AF groups compared to controls. The lowest velocities were recorded in mitral stenosis patients. Right atrial moderate-severe SEC was observed in 75% of the mitral stenosis patients, in 25% of hypertensive patients, and in 30% of hyperthyroidism patients. Right atrial thrombus was observed in 25% of mitral stenosis, 4.5% of hypertension, and in none of the hyperthyroidism patients. In the multivariate analysis, the most important parameter associated with the severity of RAA SEC was the percent change in RAA area (B =-0.034, P = 0.03).

CONCLUSION

In patients with permanent AF, impairment of RAA function and development of right atrial SEC-thrombus are closely related to the underlying etiology. These results suggested that evaluation of RAA functions may have an incremental value over the assessment of the LAA for determining thromboembolic risk.

Clinical significance of anterior mitral leaflet fibrillation in patients with nonvalvular atrial fibrillation: comparison with blood flow and wall motion of the left atrial appendage

BACKGROUND AND PURPOSE

Diastolic fibrillation of the anterior mitral leaflet (AML) is seen in patients with atrial fibrillation (AF). However, its clinical significance has been unclear. On the other hand, reduced blood flow velocity in the left atrial appendage (LAA) may be associated with LA thrombus formation. In this study, we investigate the relationship between the flow velocity and the wall motion velocity of the LAA and diastolic fibrillation of the AML in patients with nonvalvular AF.

METHODS

We performed transthoracic echocardiography (TTE) in 45 consecutive patients with chronic nonvalvular AF. The LAA flow velocity was measured by pulsed Doppler echocardiography with the sample volume positioned at the center of the LAA. The LAA wall motion velocity was measured by pulsed Doppler tissue imaging (DTI) with the sample volume at the medial wall of the LAA. The AML fibrillation velocity was measured by pulsed DTI with the sample volume at the AML tip.

RESULTS

The AML fibrillation velocity could be measured in 44 patients (97.8%), and the LAA flow and wall motion velocities were measurable in 35 (77.8%) and 42 (93.3%) patients, respectively. The AML fibrillation velocity had a range from 4 to 21 cm/s and showed significant positive correlation with the LAA flow velocity (r = 0.82, P < 0.001) and the wall motion velocity (r = 0.80, P < 0.001) of the LAA. An AML fibrillation velocity of ≤7 cm/s predicted patients having a tendency to LA thrombus formation (LAA flow velocity ≤20 cm/s) with high sensitivity (87.5%) and specificity (88.9%).

CONCLUSION

The AML fibrillation velocity seems to be a viable substitute for the LAA flow velocity in the detection of flow stagnation in the LA.

Intracardiac Thrombosis and Anticoagulation Therapy in Cardiac Amyloidosis

Background— Primary amyloidosis has a poor prognosis as a result of frequent cardiac involvement. We recently reported a high prevalence of intracardiac thrombus in cardiac amyloid patients at autopsy. However, neither the prevalence nor the effect of anticoagulation on intracardiac thrombus has been evaluated antemortem.

Methods and Results— We studied all transthoracic and transesophageal echocardiograms of cardiac amyloid patients at the Mayo Clinic. The prevalence of intracardiac thrombosis, clinical and transthoracic/transesophageal echocardiographic risks for intracardiac thrombosis, and effect of anticoagulation were investigated. We identified 156 patients with cardiac amyloidosis who underwent transesophageal echocardiograms. Amyloidosis was the primary type (AL) in 80; other types occurred in 76 patients, including 56 with the wild transthyretin type, 17 with the mutant transthyretin type, and 3 with the secondary type. Fifth-eight intracardiac thrombi were identified in 42 patients (27%). AL amyloid had more frequent intracardiac thrombus than the other types (35% versus 18%; P =0.02), although the AL patients were younger and had less atrial fibrillation. Multivariate analysis showed that atrial fibrillation, poor left ventricular diastolic function, and lower left atrial appendage emptying velocity were independently associated with increased risk for intracardiac thrombosis, whereas anticoagulation was associated with a significantly decreased risk (odds ratio, 0.09; 95% CI, 0.01 to 0.51; P <0.006).

Conclusions— Intracardiac thrombosis occurs frequently in cardiac amyloid patients, especially in the AL type and in those with atrial fibrillation. Risk for thrombosis increased if left ventricular diastolic dysfunction and atrial mechanical dysfunction were present. Anticoagulation therapy appears protective. Timely screening in high-risk patients may allow early detection of intracardiac thrombus. Anticoagulation should be carefully considered.