Predictors of left atrial thrombus in mitral valve disease

Preprocedural Multimodality Imaging in Atrial Fibrillation

Atrial fibrillation (AF) is the most common arrhythmia worldwide and is associated with increased risk of heart failure, stroke, and death. In current medical practice, multimodality imaging is routinely used in the management of AF. Twenty-one years ago, the ACUTE trial (Assessment of Cardioversion Using Transesophageal Echocardiography) results were published, and the management of AF changed forever by incorporating transesophageal echocardiography guided cardioversion of patients in AF for the first time. Current applications of multimodality imaging in AF in 2022 include the use of transesophageal echocardiography and computed tomography before cardioversion to exclude left atrial thrombus and in left atrial appendage occlusion device implantation. Transesophageal echocardiography, cardiac computed tomography, and cardiac magnetic resonance are clinically used for AF ablation planning. The decision to use a particular imaging modality in AF is based on patient's characteristics, guideline recommendation, institutional preferences, expertise, and cost. In this first of 2-part review series, we discuss the preprocedural role of echocardiography, computed tomography, and cardiac magnetic resonance in the AF, with regard to their clinical applications, relevant outcomes data and unmet needs, and highlights future directions in this rapidly evolving field.

Atrial Fibrillation in Valvular Heart Disease

Rheumatic heart disease results in significant remodeling of the atria that provides the milieu for maintaining atrial fibrillation. Some electrical remodeling is reversible and hence early intervention may prove useful. Active screening for atrial fibrillation in high-risk subset and instituting anticoagulation may reduce the devastating complications that follow. Age older than 50 years, NYHA functional class II symptoms, left atrial dimension >4.0 cm on echocardiogram in parasternal long-axis view, and gradients across the mitral valve >10 mm Hg are clinical indicators that identify the high-risk subset. Ablation strategy in this population may differ compared with the nonvalvular group.

Watch out for left atrial roof thrombus

Rheumatic mitral stenosis is often associated with thrombus formation in the left atrium (LA), especially in patients with atrial fibrillation. Although thrombus can occur anywhere within the LA, the most common site is the left atrial appendage. Therefore, it is important to carefully screen the entire LA during perioperative transesophageal echocardiography to exclude thrombus.

Interventional Echocardiography of the MV: What the Interventionalist Wants to Know

The past 2 decades have seen a proliferation of transcatheter mitral valve (MV) therapies, which are less invasive and distinct from surgical MV repair or replacement. The commonly used MV transcatheter therapies include (1) percutaneous mitral balloon commissurotomy (PMBC) for rheumatic mitral stenosis; (2) edge-to-edge repair with the MitraClip for mitral regurgitation; (3) valve-in-valve implantation in bioprosthetic MV, native MV, or mitral ring; and (4) closure of paravalvular leaks (PVLs). This article will focus on the use of echocardiography in the diagnosis, patient selection, procedural guidance, and postprocedural follow-up for PMBC, with notes on the role of transesophageal echocardiography in transcatheter interventions for prosthetic valve degeneration and PVL closure.

Native valve disease in patients with non-valvular atrial fibrillation on warfarin or rivaroxaban

OBJECTIVE

To compare the characteristics and outcomes of patients with atrial fibrillation (AF) and aortic stenosis (AS) with patients with AF with mitral regurgitation (MR) or aortic regurgitation (AR) and patients without significant valve disease (no SVD).

METHODS

Using Rivaroxaban Once-Daily, Oral, Direct Factor Xa Inhibition Compared With Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF) data, we analysed efficacy and safety outcomes, adjusting hazard ratios (HRs) for potential confounders using Cox regression analysis.

RESULTS

Among 14 119 intention-to-treat ROCKET AF trial patients, a trial that excluded patients with mitral stenosis or artificial valve prosthesis, 214 had AS with or without other valve abnormalities, 1726 had MR or AR and 12 179 had no SVD. After adjusting for prognostic factors, the composite of stroke, systemic embolism or vascular death increased approximately twofold in patients with AS (AS 10.84, MR or AR 4.54 and no SVD 4.31 events per 100 patient-years, p=0.0001). All-cause death also significantly increased (AS 11.22, MR or AR 4.90 and no SVD 4.39 events per 100 patient-years, p=0.0003). Major bleeding occurred more frequently in AS (adjusted HR 1.61, confidence intervals (CI) 1.03 to 2.49, p<0.05) and MR or AR (HR 1.30, 1.07 to 1.57, p<0.01) than in no SVD, but there was no difference between AS and MR or AR (HR 1.24, 0.78 to 1.97). The relative efficacy of rivaroxaban versus warfarin was consistent among patients with and without valvular disease. Rivaroxaban was associated with higher rates of major bleeding than warfarin in patients with MR or AR (HR 1.63, 1.15 to 2.31).

CONCLUSIONS

We found that patients with AF and AS on oral anticoagulants may have distinctly different efficacy and safety outcomes than patients with MR or AR or no SVD.

TRIAL REGISTRATION NUMBER

NCT00403767; Post-results.

Left atrial appendage functions in patients with severe rheumatic mitral regurgitation

AIM

The left atrial appendage (LAA) function was evaluated in patients with severe rheumatic mitral regurgitation, having sinus rhythm or atrial fibrillation, by standard and tissue Doppler echocardiographic examinations.

METHODS AND RESULTS

Sixty patients with rheumatic severe mitral regurgitation were enrolled. The patients (14 females and 6 males) having sinus rhythm were selected as group I and 20 patients (15 females and 5 males) with atrial fibrillation formed group II. 20 healthy subjects (15 female and 5 males) served as the control group (group III). In order to determine the LAA functions, LAA peak filling flow velocity (LAAPFV), LAA peak emptying flow velocity (LAAPEV) and percentage of LAA area change (LAAAC %) were measured. In the TDI records of the subjects with sinus rhythm, the first positive wave identical to the LAA late emptying wave (LEW) following the P-wave was accepted as LAA late systolic wave (LSW), and the second negative wave identical to the LAA late filling flow was accepted as late diastolic wave (LDW). In patients with atrial fibrillation, the positive wave was accepted as LAA late systolic wave (LSW), and the second negative wave identical to the LAA late filling flow was accepted as late diastolic wave (LDW). LAA outflow and inflow velocities were lower in the group having atrial fibrillation (P < 0.002, and P < 0.007, respectively). LAAAC% was also reduced in group II (P < 0.0001). The pulsed Doppler LSW and LDW velocities, measured with TDI method were found to be quite reduced in patients with AF (P: 0.002 and P: 0.001, respectively). The study parameters were statistically similar in patients with normal sinus rhythm and controls.

CONCLUSION

In this study, we found that the LAA functions are impaired in patients with severe mitral regurgitation, having AF, whereas preserved in patients with normal sinus rhythm, compared to controls.

Assessment of left atrial appendage filling pattern by using intravenous administration of microbubbles: comparison between mitral stenosis and mitral regurgitation

Mitral stenosis (MS) and mitral regurgitation (MR) are the most frequent conditions that cause a dilation and dysfunction of the left atrial appendage (LAA). Despite similarly dilated LAA in patients with MS and MR, the incidence of LAA thrombi and the risk of thromboembolism is different between these patients. The purpose of this study was to characterize the filling pattern of LAA by using intravenous administration of perfluorocarbon-exposed dextrose albumin (PESDA) during transesophageal echocardiographic examination in patients with MS and MR. Twenty-four patients with moderate to severe MS, 12 patients with severe MR, and a control group including 30 patients with conditions other than mitral valve disease underwent transesophageal echocardiographic examination with an intravenous bolus injection of PESDA. LAA emptying and filling velocities and maximal and minimal areas of LAA and LAA ejection fraction were measured. Digital gray-scale intensity (GSI) of the left atrial (LA) and LAA cavity after PESDA injection was measured by off-line analysis. Compared with control patients, patients with MS or MR had larger maximal and minimal areas of LAA and reduced LAA ejection fraction. LAA peak emptying flow velocity was significantly lower in patients with MS compared with those of MR or control patients. LAA peak filling velocity was significantly lower in patients with MS compared with that of control patients. However, there was no significant difference of LAA peak filling velocity between the patients with MS and MR. There was no significant difference of GSI ratio of LAA and LA between patients with MR and control patients; however, GSI ratio of LAA and LA was significantly lower in patients with MS compared with that of MR. The incidence of LAA spontaneous echo contrast and LAA thrombi in patients with MS was significantly higher than that of the patients with MR and control subjects (P <.005). Despite similarly dilated LAA area and depressed contractile function of LAA in patients with MS and MR compared with control patients, profoundly impaired LAA filling with resultant flow stasis was demonstrated by contrast echocardiography in patients with MS. These findings may explain the higher incidence of LAA spontaneous echo contrast and thrombus in patients with MS.

Transesophageal echocardiography risk factors for stroke in nonvalvular atrial fibrillation

Atrial fibrillation is a common arrhythmia, particularly in the older age groups. It confers an increased risk of thromboembolism to these patients, and multiple clinical risk factors have been identified to be useful in predicting the risks of thromboembolic events. Recent studies have evaluated the role of transesophageal echocardiography (TEE) in the evaluation of patients with atrial fibrillation. The purpose of this review is to evaluate the significance of transesophageal echocardiographic findings in the prediction of thromboembolic events, particularly stroke, in patients with nonvalvular atrial fibrillation, with an emphasis on recently reported prospective studies. Aortic plaque and left atrial appendage abnormalities are identified as independent predictors of thromboembolic events. Although they are associated with clinical events, they also have independent incremental prognostic values. Other transesophageal echocardiographic findings, such as patent foramen ovale and atrial septal aneurysm, have not been found to be predictors of thromboembolic events in this patient group. Thus, TEE is a useful tool in stratifying patients with nonvalvular atrial fibrillation into different risk groups in terms of thromboembolic events, and it will likely play an important role in future studies to assess new treatment strategies in high-risk patients with atrial fibrillation.

Mitral regurgitation reduces the risk of stroke in patients with nonrheumatic atrial fibrillation

BACKGROUND

Significant mitral regurgitation (MR) is protective against left atrial (LA) spontaneous echo contrast formation that is associated with an increased thromboembolic risk. However, the effects of MR on the risk of stroke in patients with nonrheumatic atrial fibrillation (AF) have been unknown. We studied whether or not MR was associated with a decreased risk of stroke in patients with nonrheumatic AF.

METHODS

We performed an observational analysis of retrospectively collected data on 290 patients with nonrheumatic AF. Left atrial diameter (LAD) and the degree of MR were estimated by transthoracic echocardiography. Risk factors for stroke were assessed by univariate and multivariate analyses. The mean follow-up was 7.4 years.

RESULTS

Among these patients, 68 had a stroke during the follow-up (rate of stroke per year of follow-up 3.2%). In 95 patients with LAD of > or =48 mm, the incidence of stroke (9%) in the severe MR group (moderate or severe, n=43) was significantly lower than that (25%) of the mild MR group (none, trivial, or mild; n=52) (chi-square=3.95, p=0.047). The relative risk of stroke for increase in MR from mild to severe groups, for every 10 mm increment in LA size, for sex, and for every increase of 10 years of age was 0.45 (95% CI, 0.20 to 0.97), 1.06 (95% CI, 0.75 to 1.49), 0.98 (95% CI, 0.55 to 1.72), and 1.33 (95% CI, 1.04 to 1.71), respectively.

CONCLUSIONS

In patients with nonrheumatic AF, age was an independent predictor of an increased risk of stroke, and MR may be protective against stroke, especially in those patients with LA enlargement.