Predictors of left atrial thrombus and spontaneous echo contrast in rheumatic valve disease before and after mitral valve replacement

Severe Left Atrial Spontaneous Echo Contrast in Nonvalvular Atrial Fibrillation: Clinical Characteristics and Impact on Ischemic Risk Postablation

BACKGROUND

 Spontaneous echo contrast (SEC) is an important precursor for intracardiac thrombus and stroke. There are very limited data on characteristics of severe SEC and its impact on ischemic risk of nonvalvular atrial fibrillation (NVAF) patients after radiofrequency catheter ablation.

METHODS

 Transesophageal echocardiography files were reviewed between March 2009 and March 2021 in this monocentric retrospective study. SEC was classified into four levels. The primary endpoint was thromboembolic event (stroke, myocardial infarction, systemic embolism, and ensuing death), and the secondary endpoint included nonischemic mortality and recurrent atrial arrhythmia.

RESULTS

 Six hundred SEC cases were enrolled and classified into mild SEC group (Grade 1-2, n = 515) and severe SEC group (Grade 3-4, n = 85). Independent risk factors for severe SEC included higher brain natriuretic peptide (BNP), erythrocyte sedimentation rate (ESR), and LAd/∆LVED (LAd = left atrial diameter; ∆LVED = left ventricular end-diastolic diameter - left ventricular end-systolic diameter). The severe SEC group had a higher peri-procedural ischemic event occurrence (7.1 vs. 1.9%, p = 0.007). At a median follow-up of 55 months, the severe SEC group had a lower freedom rate from ischemic events (90.1 vs. 75.3%, p < 0.001); older age and severe SEC were independent risk factors for ischemic events. In patients undergoing redo-procedure (n = 100), a remarkably reduced ESR (17.8 ± 12.0 vs. 28.2 ± 19.0 mm/h, p < 0.001) was observed in patients whose SEC disappeared.

CONCLUSIONS

 Higher BNP, ESR, and LAd/∆LVED were the independent predictors for severe SEC. Severe SEC was associated with higher peri-procedural and long-term ischemic risks. ESR and LAd/∆LVED, as indicators of hematological and hemodynamic change, seemed helpful in identifying NVAF patients prone to developing severe SEC.

Effect of mitral regurgitation on stroke risk in patients with non-rheumatic atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) carries a thrombotic risk related to blood stasis in the left atrium. In patients with rheumatic valve disease and AF, the presence of severe mitral regurgitation (MR) has been shown to reduce the risk of atrial thrombosis and stroke. However, in patients without rheumatic disease, the results are controversial.

AIM

To analyse the association between MR and the incidence of stroke in patients with non-rheumatic AF.

METHODS

We analysed data from the retrospective CardioCHUVI-AF registry, which includes 15,720 patients with AF (without mechanical prostheses or rheumatic valvular disease) in the Vigo area of Spain, during 2014-2018. We grouped the patients according to MR grades: 0-2 (n=15,194) and 3-4 (n=526). We performed univariate and multivariable competitive risk analyses to analyse the association between MR and stroke, with death as the competitive event.

RESULTS

During a median (interquartile range [IQR]) follow-up of 4.9 (2.8-4.9) years, 859 patients (5.5%) suffered a stroke. The stroke incidence was 1.3 per 100 person-years (95% confidence interval [95% CI]: 1.2-1.4), with no difference between the MR groups. In univariate analysis, no relationship was observed between MR grade and stroke (subdistribution hazard ratio [sHR]: 1.12, 95% CI: 0.79-1.60; P=0.53); likewise after multivariable analysis (sHR: 0.98, 95% CI: 0.68-1.41; P=0.90). This same relationship was evaluated in subgroups of interest (patients with and without: oral anticoagulation, CHA₂DS₂-VASc≥2, prior heart failure, aortic valve disease, left ventricular ejection fraction≤40%, and moderate-severe left atrial dilation), with results consistent with the overall population.

CONCLUSION

In our large registry of patients with non-rheumatic AF, we did not find a protective effect of grade 3-4 MR on the risk of stroke.

Effect of Mitral Regurgitation on Systemic Coagulation Activity in Rheumatic Heart Disease as Assessed by D-dimer Levels

Introduction

Atrial fibrillation and mitral stenosis, especially in combination, increase the risk of left atrial thrombus formation and systemic embolization. However, whether severe mitral regurgitation (MR) improves systemic hypercoagulable state in these patients is unclear. remains unclear. The study aims to study the impact of severe MR on systemic coagulation by the use of D-dimer levels.

Methods

It was a prospective, cross-sectional study done on 400 subjects consisting of 350 cases and 50 controls. The cases were divided into seven groups on basis of valvular pathology, rhythm, and presence of a clot. The D-dimer level was compared in all the subgroups.

Result

The mean age of the study population was 32.32±7.30 years with a 48% male population. The highest level of D-dimer was found in patients with thrombus (1.71 ± 1.74 µg/ml). Patients with mitral stenosis had significantly higher plasma D-dimer levels than the control group (p <0.001) while regardless of rhythm, patients with MR had a D-dimer level similar to the control group in sinus rhythm.

Conclusion

Severe MR reduces plasma D-dimer levels to control levels reflecting the protective effect against thrombus formation and systemic embolization.

Does patent foramen ovale presence procure favourable outcomes in patients with severe rheumatic mitral stenosis?

Mitral stenosis (MS) is tolerated for an extended period in patients with atrial septal defect (ASD) known as Lutembacher syndrome due to depressurizing effect. In a similar way, patients with patent foramen ovale (PFO) may have clinical benefits in severe MS. We aim to evaluate the clinical effects of PFO in rheumatic MS. Transthoracic and transesophageal echocardiography records of the patients with symptomatic severe MS were screened for the period between 2008 and 2019 in a single center. 320 symptomatic patients with severe MS were included and presence of PFO recorded. Left atrial appendix (LAA) thrombotic status was defined as clear, spontaneous echo contrast, and thrombus. Two different statistical models were used to determine the predictors of either smallest (mitral valve area) MVA at symptomatic presentation or more thrombogenic LAA. 34 patients had PFO. Multivariable ordinary least square model demonstrated that increase in systolic pulmonary arterial pressure, ejection fraction and presence of PFO were associated with smaller MVA on presentation. Multivariable proportional odds logistic regression model demonstrated that advanced age, increased left atrial diameter, absence of PFO were associated with more thrombotic status whereas larger MVA was associated with decreased thrombotic status in LAA. Presence of PFO in severe MS results in two clinical benefits as (i) being asymptomatic with smaller MVA and (ii) having less LAA thrombosis probably caused by depressurizing effect on the left atrial pressure. Our study could serve as an example for patient groups with expected symptomatic benefits from left atrium pressure offloading interventions.

Differentiation of left atrial appendage thrombus from circulatory stasis using cardiac CT radiomics in patients with valvular heart disease

OBJECTIVES

To determine whether quantitative radiomic features from cardiac CT could differentiate the left atrial appendage (LAA) thrombus from circulatory stasis in patients with valvular heart disease.

METHODS

Ninety-five consecutive patients with valvular heart disease and filling defects in LAA on two-phase cardiac CT from March 2016 to August 2018 were retrospectively enrolled and classified as having thrombus or stasis by transesophageal echocardiography or cardiac surgery. The ratio of Hounsfield units in the filling defects to those in the ascending aorta (AA) was calculated on early- and late-phase CT (LAA/AA_E and LAA/AA_L, respectively). Radiomic features were extracted from semi-automated three-dimensional segmentation of the filling defect on early-phase CT. The diagnostic ability of radiomic features for differentiating thrombus from stasis was assessed and compared to LAA/AA_E and LAA/AA_L by comparing the AUC of ROC curves. Diagnostic performances of CT attenuation ratios and radiomic features were validated with an independent validation set.

RESULTS

Thrombus was diagnosed in 25 cases and stasis in 70. Sixty-eight radiomic features were extracted. Values of 8 wavelet-transformed features were lower in thrombus than in stasis (p < 0.001). The AUC value of a radiomic feature, wavelet_LHL, for diagnosing thrombus was 0.78, which was higher than that of LAA/AA_E (AUC = 0.54, p = 0.025) and similar to that of LAA/AA_L (AUC = 0.76, p = 0.773). In the validation set, the AUC of wavelet_LHL was 0.71, which was higher than that of LAA/AA_E (AUC = 0.57, p = 0.391) and similar to that of LAA/AA_L (AUC = 0.75, p = 0.707).

CONCLUSIONS

Quantitative radiomic features from the early phase of cardiac CT may help diagnose LAA thrombus in patients with valvular heart disease.

KEY POINTS

• Wavelet-transformed grey-level non-uniformity values from radiomic analysis are significantly lower for LAA thrombus than for circulatory stasis. • Radiomic features may have an additional value for differentiating LAA thrombus from circulatory stasis when interpreting single-phase cardiac CT. • Radiomic features extracted from single-phase images may show similar diagnostic ability as conventional quantitative analysis from two-phase images.

Long-term left atrial thrombi after mitral valve replacement

The aim of this study was to evaluate the risk factors and characteristics of long-term postoperative left atrial (LA) thrombi after mitral valve replacement. Transthoracic echocardiography (TTE) file of 3117 consecutive patients with mitral valve replacement history was reviewed (between Jan 2006 and Feb 2019). 45 LA thrombi cases (1.4%) was identified and matched to 180 thrombi-free cases by random sampling. The median detection time of LA thrombi was 58 months (IQR, 17-144) after MV replacement. Distribution of LA thrombi included roof (n = 10), posterior wall (n = 9), appendage (n = 7), lateral wall (n = 6), anterior wall (n = 2), septum (n = 1) and multiple site (n = 10). All thrombi were sessile and immobile. The independent predictors for LA thrombi development by stepwise multiple regression analysis were the larger LA size (> 55 mm), the increased of mitral valve pressure gradient (MVPG > 6 mmHg), and the reduced of left ventricular ejection fraction (LVEF < 50%). Long-term thrombi incidence after mitral valve replacement is somewhat low. In individuals with mitral prosthetic valves, larger LA size, increased MVPG and reduced LVEF were three promising independent predictors of the insistence of LA thrombi. Furthermore, LA thrombi were sessile, immobile and widespread in the long-term postoperative period after mitral valve replacement. Close monitoring should be applied in these patients with thrombi risk.

Meta-Analysis of the Incidence, Prevalence, and Correlates of Atrial Fibrillation in Rheumatic Heart Disease

Objective:

To estimate the incidence, prevalence, and correlates of atrial fibrillation (AF) in a global population with rheumatic heart disease (RHD).

Methods:

Bibliographic databases were searched to identify all published studies providing data on AF in patients with RHD. Random-effects meta-analysis method was used to pool estimates.

Results:

Eighty-three studies were included, reporting data from 75,637 participants with RHD in 42 countries. The global prevalence of AF in RHD was 32.8% (range: 4.3%–79.9%). It was higher in severe valvular disease (30.8% vs 20.7%, p = 0.009), in severe mitral valve disease compared to severe aortic disease (30.4% vs 6.3%, p = 0.038). The global cumulative incidence of AF in patients with RHD was 4.8%, 11.4%, 13.2%, and 30.8% at 1, 2, 5, and 10 years of follow-up, respectively. From comparison between patients with and without AF, AF was associated with increased age (mean difference [MD]: 9.5 years; 95% CI: 7.8–1.3), advanced heart failure (odds ratio [OR]: 4.4; 95% CI 2.1–9.3), tricuspid valve involvement (OR: 4.0; 95% CI: 3.0–5.3), history of thromboembolism (OR: 6.2; 95% CI: 3.4–11.4), highly sensitive C-reactive protein (MD: 5.5 mg/dL; 95% CI: 1.2–9.8), systolic pulmonary arterial pressure (MD: 3.6 mmHg; 95% CI: 0.8–6.3), right atrium pressure (MD: 1.5 mmHg; 95% CI: 1.0–2.0), and left atrium diameter (MD: 8.1 mm; 95% CI: 5.5–10.7).

Conclusions:

About one-third of patients with RHD have AF, with an incidence which almost triples every five years after diagnosis. Factors associated with AF include age, advanced heart failure, thromboembolism, and few cardiac hemodynamics parameters.

Does mitral regurgitation reduce the risks of thrombosis in atrial fibrillation and flutter?

AIMS

Blood stasis is the main cause of left atrial thrombosis (LAT) in atrial tachyarrhythmias. The high-velocity flow inside the left atrium, due to mitral valve regurgitation, may prevent clot formation but the topic has never been investigated in large-scale studies. The aim of our study was to evaluate whether the presence and degree of mitral regurgitation have a protective role against LAT risk.

METHODS

A total of 1302 consecutive adult patients with paroxysmal or persistent atrial fibrillation or flutter undergoing cardioversion, submitted to transesophageal echocardiography, were retrospectively enrolled in the study. The study population was divided into three groups according to the mitral regurgitation degree: absent, mild-to-moderate and severe.

RESULTS

Among 1302 patients enrolled in the study, patients without mitral regurgitation were 248 (19%), those with mild-to-moderate 970 (75%), whereas 84 had severe mitral regurgitation (6%). LAT incidence was significantly lower in patients with severe mitral regurgitation compared with those with mild-to-moderate (mitral regurgitation) (2.4 vs. 8.9%, P < 0.05), and similar to subjects without mitral regurgitation (2.4%).

CONCLUSION

Despite patients with severe regurgitation having clinical and echo characteristics predisposing to LAT (higher age, heart failure, higher atrial size, lower ventricular function) thrombosis prevalence was significantly lower than for those with mild-to-moderate mitral regurgitation. The percentage of LAT in severe mitral regurgitation cases was very low and similar to that of cases without regurgitation which were characterized by lower age, normal left ventricular function or other risk factors, reinforcing the hypothesis of a protecting role against atrial thrombosis of mitral regurgitation.

Predictive factors of left atrial spontaneous echo contrast in patients with rheumatic mitral valve stenosis: a retrospective study of 159 patients

Background

Mitral valve stenosis is a common manifestation of chronic rheumatic heart disease. The presence of spontaneous echo contrast in the left atrium and left atrial appendage has been reported to be an independent predictor of thrombo-embolic risk in patients with mitral stenosis. The objective of this study was to retrospectively investigate various clinical and echocardiographic variables to predict the spontaneous echo contrast in these patients.

Methodology

This is a bicentric retrospective study which includes 159 cases of symptomatic mitral stenosis from January 2011 to June 2012. All of the patients had transthoracic and transesophageal echocardiography. Patients who had significant mitral regurgitation (> Grade I), significant aortic valve disease, previous mitral valvulotomy and anticoagulation or antiplatelet therapy were excluded from the study. Our study population was divided into two groups based on the presence (Group I) or absence (Group II) of spontaneous echo contrast.

Result

Left atrial spontaneous contrast was present in 34.6% of cases. Patients in this group have more frequent atrial fibrillation (P = 0.001), larger left atrial area (P = 0.027) and diameter (P=0.023), smaller mitral valve area (P = 0.025), and higher mean transmitral diastolic gradient (p = 0.003) as compared to patients without spontaneous echo contrast. There were no significant differences in the mean age (p = 0.38), duration of symptoms (p = 0.4) and left ventricular ejection fraction (p = 0.7) between patients with and without spontaneous echo contrast. On multivariate analysis, only mitral valve area and transmitral diastolic gradient (OR: 18.753, 1.21, CI [1,838-191,332], [1,064-1,376], p: 0.013, 0.004, respectively) were found to be independently associated to the presence of spontaneous echo contrast.

Conclusion

Patients with severe rheumatic mitral stenosis in atrial fibrillation or sinus rhythm have a higher risk of developing spontaneous echo contrast. These patients might benefit from prophylactic anticoagulation. The long-term outcomes can be ascertained in a study over a longer period and with periodic follow-up.

Dual-enhanced cardiac CT for detection of left atrial appendage thrombus in patients with stroke: a prospective comparison study with transesophageal echocardiography

BACKGROUND AND PURPOSE

A noninvasive method with high reliability and accuracy comparable to transesophageal echocardiography for identification of left atrial appendage thrombus would be of significant clinical value. The aim of this study was to assess the diagnostic performance of a dual-enhanced cardiac CT protocol for detection of left atrial appendage thrombi and for differentiation between thrombus and circulatory stasis in patients with stroke.

METHODS

We studied 83 consecutive patients with stroke (56 men and 27 women; mean age, 62.6 years) who had high risk factors for thrombus formation and had undergone both dual-source CT and transesophageal echocardiography within a 3-day period. CT was performed with prospective electrocardiographic gating, and scanning began 180 seconds after the test bolus.

RESULTS

Among the 83 patients, a total of 13 thrombi combined with spontaneous echo contrast and 14 spontaneous echo contrasts were detected by transesophageal echocardiography. All 13 thrombi combined with spontaneous echo contrast were correctly diagnosed on CT. Using transesophageal echocardiography as the reference standard, the overall sensitivity and specificity of CT for the detection of thrombi and circulatory stasis in the left atrial appendage were 96% (95% CI, 78% to 99%), and 100% (95% CI, 92% to 100%), respectively. On CT, the mean left atrial appendage/ascending aorta Hounsfield unit ratios were significantly different between thrombus and circulatory stasis (0.15 Hounsfield unit versus 0.27 Hounsfield unit, P=0.001). The mean effective radiation dose was 3.11 mSv.

CONCLUSIONS

Dual-enhanced cardiac CT with prospective electrocardiographic gating is a noninvasive and sensitive modality for detecting left atrial appendage thrombus with an acceptable radiation dose.

Annular systolic velocity predicts the presence of spontaneous echo contrast in mitral stenosis patients with sinus rhythm

OBJECTIVES

Thromboembolism is the major cause of morbidity and mortality in mitral stenosis (MS), even in sinus rhythm (SR). Spontaneous echo contrast (SEC) is the strongest predictor of thromboembolism. The aim of the study was to investigate if the annular velocities obtained with tissue Doppler imaging can predict the presence of SEC in MS patients with SR.

METHODS

One hundred and five MS patients and 100 controls were included. Annular velocities were recorded. All patients underwent transesophageal echocardiography. Subjects were divided into three groups as controls (Group I), the patients without SEC (Group II) and the patients with SEC (Group III).

RESULTS

Group III patients had lower ejection fraction, annular systolic velocity, smaller mitral valve area, higher transmitral gradient and larger left atrial size. The annular systolic velocity was the only independent predictor for SEC. The cutoff values of annular systolic velocity for prediction of the presence of any SEC and dense SEC were 13.5 and 11.8 cm/s, respectively.

CONCLUSION

The annular systolic velocity is an independent predictor for SEC in MS patients with SR.

Clinical and Echocardiographic Risk Factors for Embolization in the Presence of Left Atrial Thrombus

AIMS

The aim of our study was to evaluate the factors leading to embolization in patients with left atrial thrombi (LAT). With this purpose, we retrospectively analyzed clinical, transthoracic, transesophageal echocardiographic data of patients with LAT in the transesophageal echocardiographic evaluation.

METHODS AND RESULTS

One hundred ninety-two patients with LAT not on anticoagulant therapy were divided into two groups according to the presence of prior ischemic stroke. The group with ischemic stroke included more patients with sinus rhythm and less patients with mitral stenosis. They had smaller left atrial diameter, more left atrial appendage spontaneous echo-contrast, higher appendage ejection fraction, and emptying velocity.

CONCLUSION

Once the thrombus has been formed, cerebral embolization seems to be higher in patients with relatively preserved appendage ejection fraction and emptying velocity. Presence of atrial appendage spontaneous echo-contrast also favor embolization. Factors leading to embolization seem to differ in some respects from the causes of thrombus formation.

Relation between Sympathetic Overactivity and Left Atrial Spontaneous Echo Contrast in Patients with Mitral Stenosis and Sinus Rhythm

BACKGROUND

Spontaneous echo contrast (SEC) is common in patients with mitral stenosis (MS) and presence of SEC in left atrium (LA) is associated with a higher risk of thromboembolism. Recently, an increase in activation of platelets was demonstrated in patients with SEC raising the hypothesis that platelets are involved in the pathogenesis of SEC. In this study, we evaluated effects of autonomic nervous system activity on SEC formation in patients with rheumatic MS and sinus rhythm by heart rate variability analysis.

METHODS AND RESULTS

Twenty-six patients with LASEC were compared with 28 patients without LASEC. Mean heart rate, low frequency (LF) and low frequency/high frequency (LF/HF) ratio were significantly higher, standard deviation of all NN (SDNN), root mean square of successive differences (RMSSD), number of NN intervals that differed by more than 50 ms from adjacent interval divided by the total number of all NN intervals (PNN50) and high frequency (HF) values were lower in the patients with LASEC. A standard deviation of all NN intervals <90ms separated the patients with LASEC from control subjects with a sensitivity of 77% and specificity of 90%; a low frequency >79.5 with a sensitivity of 92% and specificity of 90; a low frequency/high frequency ratio >3.7 with a sensitivity of 96% and specificity of 90%. A left atrial diameter >4.3 cm increased the LASEC formation by 3.0 folds, HR >78 beats/min by 6.4 folds, standard deviation of all NN intervals <90 ms by 9.2 folds, a low frequency/high frequency ratio >3.7 by 6.4 folds, sP-selectin>142 by 5.8 folds. Variables affecting sP-selectin levels were LA diameter, mitral valve area, transmitral mean gradient, left ventricular ejection fraction, the presence of mitral regurgitation, HR, standard deviation of all NN intervals, low frequency, high frequency and low frequency/high frequency ratio.

CONCLUSION

Sympathetic overactivity and reduced heart rate variability are important determinants for LASEC formation and increased s-P selectin levels. Therefore, platelet activation via increased sympathetic activity may play an important role in pathogenesis of LASEC.

Clinical significance of early thrombosis after prosthetic mitral valve replacement: a postoperative monocentric study of 680 patients

OBJECTIVES

The aim of this study was to evaluate the incidence of early thrombosis, its prognostic significance, and the therapeutic implications.

BACKGROUND

Transesophageal echocardiography (TEE) is the method of choice for detecting symptomless early postoperative thrombosis of prosthetic valves. However, the clinical significance is not yet known.

METHODS

Between June 1994 and December 2000, 680 consecutive patients underwent TEE on day 9 after mechanical mitral valve replacement, to search for early thrombosis. Initially, end points were the in-hospital outcome and treatment. Patients were also evaluated 34 +/- 22 months after surgery.

RESULTS

Sixty-four early thrombi were detected (9.4%). Two early obstructive were treated by redo-surgery. Sixty-two nonobstructive benefited from medical treatment. The patients were allocated into two groups as a function of the maximum size of thrombus: <5 mm in 29 patients (group A) and > or =5 mm in 35 (group B). During early follow-up, we observed one complicated course in group A and eight in group B. In the long-term survey, three complications were noted in group A and 11 in group B. Incidence of early (p = 0.027) and long-term (p = 0.04) complications were significantly different in the two subsets.

CONCLUSIONS

This study confirms the incidence of early thrombi after mechanical mitral valve replacement detected by TEE. A small (<5 mm) nonobstructive thrombus seems benign, and our experience argues in favor of medical treatment. Prognosis appears more serious for large thrombi. Medically aggressive therapy and further surgery should be considered in cases of obstructive thrombosis or large and mobile nonobstructive thrombosis.

Spontaneous echo contrast videodensity is flow-related and is dependent on the relative concentrations of fibrinogen and red blood cells

OBJECTIVES

The purposes of the present study were to: 1) determine whether fibrinogen (Fg) is the plasma protein responsible for spontaneous echo contrast (SEC), and 2) investigate modulators of SEC.

BACKGROUND

Spontaneous echo contrast has been linked to the development of thromboemboli. The blood products and their interaction responsible for SEC formation have not been fully elucidated.

METHODS

Blood echogenicity was examined with the use of quantitative videodensitometry over a controlled range of flow velocities in an in vitro model. Human blood samples were analyzed in a manner to methodically eliminate individual blood components from whole blood to determine which components are responsible for the formation of SEC.

RESULTS

The videodensity (VD) of whole blood was found to be flow-dependent, with higher VD at lower flow rates, and correlated with visually dense SEC. The following blood products produced faint VD values: washed red blood cells (wRBCs), platelet-depleted plasma, Fg, defibrinated plasma, wRBCs plus defibrinated plasma, and physiologic saline. The VD of wRBCs increased incrementally as increasing concentrations of Fg were added. At each hematocrit (Hct) range, as Fg concentration increased, the SEC became denser, and the VD level also increased until a plateau level was reached that was distinct for each Hct. The addition of sialic acid, which inhibits RBC-RBC aggregation, decreased the amount of SEC, even in the presence of Fg.

CONCLUSION

These results demonstrated that Fg-mediated RBC aggregation may be responsible for SEC generation. Furthermore, a unique stoichiometric relationship exists between Fg and RBC concentrations that is necessary for blood echogenicity.

Severe mitral regurgitation may prevent mural thrombus formation within the left ventricle with systolic dysfunction

The protective effect of severe mitral regurgitation (MR) against left atrial thrombus formation has been well documented. It was also proposed that severe MR may prevent thrombus formation within the left ventricle (LV) with systolic dysfunction. Therefore, we investigated whether ischemic MR prevents thrombus formation within the LV in patients with systolic dysfunction. The study population was comprised of 1313 patients (1133 males, 180 females, age 56+/-18) with ischaemic LV dysfunction documented by coronary angiography and left ventriculography. None of the patients had a history of chronic anticoagulation. Epicardial coronary arteries were normal in 91 patients, and single-vessel, two-vessel, and triple-vessel disease were detected in 328, 330, and 564 patients, respectively. Left ventricular thrombus and severe MR were detected in 191 (14.5%) and 125 (9.5%) patients, respectively. Overall incidence of LV thrombus was lower in patients with severe MR than in patients without severe MR (4% vs 15.6%, OR: 0.2, P<0.001). Severe MR compared with absence of severe MR was associated with a lower incidence of LV thrombus both in patients with ischemic dilated cardiomyopathy (6.8% vs 34.2%, OR: 0.19, P<0.001), and in patients with aneurysm (3% vs 18%, OR: 0.14, P<0.0001) involving anterolateral, septal and/or apical LV segments. A similar trend without statistical significance was also observed in patients with dyskinesia (4.7% vs 16%, OR: 0.26, P=0.1) related to anterolateral, septal and/or apical LV segments. However, MR had no impact on the incidence of LV thrombus in patients with aneurysm or dyskinesia related to posterior and/or inferior segments (3.7% vs 3%, OR: 1.2, P>0.05). In conclusion, severe MR seems to prevent LV mural thrombus formation in patients with ischemic dilated cardiomyopathy, and in patients with aneurysm related to anterolateral, septal, and/or apical LV segments. This relative risk reduction may be associated with diastolic volume overloading due to severe MR which may overcome stagnation and a procoagulant state within the LV with severe systolic dysfunction.

Spontaneous echocardiographic microbubbles associated with prosthetic mitral valves: mechanistic insights from thrombolytic treatment results

The purpose of this study was to determine the prevalence of microbubbles (MBs) in patients with prosthetic mitral valves (PMVs). The clinical and echocardiographic predictors of MB were investigated. We also analyzed the temporal relation between MBs and the thrombolytic treatment of thrombotic PMV dysfunction. The study material comprised 307 transesophageal echocardiography examinations in 279 patients (170 women and 109 men with a mean age of 37.9 +/- 13.3 years) with PMV. The PMV was mechanical in 245 patients (tilting-disk valves in 129, and bileaflet aortic valves in 116) and bioprosthetic mitral valves in 34 patients. Twenty-eight sessions of thrombolytic treatment were performed because of the obstructive (n = 18) and nonobstructive (n = 10) thrombi involving the PMV. No MBs were seen in any of the bioprosthetic valves. The MBs were present in 128 of 227 (56.4%) PMV without obstruction compared with only 1 of 18 (5.5%) valves with thrombotic obstruction (P <.0001). The MB were documented in 75.4% of the normal bileaflet valves compared with 38.5% of the tilting-disk valves (P <.0001). The MB intensity score was also significantly higher in the bileaflet valves (2.0 +/- 0.8 vs 0.7 +/- 0.7, P <.05). The incidence of MBs increased from 5.5% to 68.7% after successful thrombolysis in patients with obstructive PMV thrombi (P <.001). There were no other predictors of MBs in this series. The passage of MBs in the aortic root was not documented in any instances. We conclude that MBs are normal echocardiographic findings depending on the type and function of the mechanical PMVs.

Clinical and echocardiographic characteristics of patients with left atrial thrombus and sinus rhythm: experience in 20 643 consecutive transesophageal echocardiographic examinations

BACKGROUND

Left atrial (LA) thrombus is infrequently detected in the presence of sinus rhythm (SR) and, in these cases, is usually associated with additional cardiac pathologies. We sought to determine the clinical and echocardiographic characteristics of patients with LA thrombus and SR to define a high-risk group of patients prone to this uncommon clinical presentation.

METHODS AND RESULTS

The institution's echocardiographic laboratory database was searched to identify patients with LA thrombus, diagnosed by transesophageal echocardiography (TEE), who were in SR during the TEE examination. Of 20 643 consecutive TEE examinations performed during an 11-year period, LA thrombus was detected in 314 patients in 380 TEE examinations. Of these, SR was present in 20 patients (age 69+/-13 years; 40% men) in 23 examinations (0.1% of all TEE examinations; 6.1% of TEE examinations with LA thrombus). High-risk structural heart disease (severe left ventricular dysfunction or significant left-sided valve disease [predominantly mitral valve disease]), previous documented episodes of atrial fibrillation, or both (structural heart disease and previous atrial fibrillation) were present in 10, 4, and 5 of the 20 patients, respectively. Only 1 patient with LA thrombus and SR did not have high-risk features.

CONCLUSIONS

LA thrombus is very infrequently detected in the presence of SR. Patients with LA thrombus and SR constitute a high-risk group characterized by specific structural cardiac abnormalities or previous atrial fibrillation, abnormalities that are potentially detectable before TEE.

Mitral regurgitation protects from left atrial thrombogenesis in patients with mitral valve disease and atrial fibrillation

The aim of this study was to test the hypothesis that mitral regurgitation (MR) has a protective effect on the development of left atrial thrombus (LAT) in patients with rheumatic heart disease and atrial fibrillation (AF). The study population consisted of 48 anticoagulated patients (mean age = 57.1 +/- 10 years). Predominant mitral stenosis (MS) was present in 14 patients, predominant MR in 14, and a mechanical valve in 20. All patients underwent detailed transesophageal echocardiography. Severity of MR was based on measurements of the MR jet by color flow mapping. Patients were divided into two groups: (a) those with MR > or = 3+ (n = 12, 25%), and (b) those without significant MR (n = 36, 75%). A LAT was found in six patients (12.5%), who also had spontaneous echo contrast (SEC), while another group of 30 patients (62.5%) had SEC only. LAT and/or SEC were present in 2/12 patients (16.6%) with significant MR versus 34/36 patients (94.4%) without significant MR (P < 0.001). In addition to the absence of significant MR, left atrial diameter (LAD) > 60 mm, and severity of MS were also related to the presence of thrombus and/or SEC. Significant MR had a protective effect against thromboembolism, although this effect was abolished if LAD > 60 mm was present. In conclusion, in patients with mitral valve disease and AF, significant MR protects against LAT formation and systemic embolization. This protective effect was lost when LAD was > 60 mm.

Predictors of left atrial spontaneous echo contrast and thrombi in patients with mitral stenosis and atrial fibrillation

The purpose of this study was to investigate the independent factors associated with the presence of left atrial (LA) spontaneous echo contrast (SEC) and thromboembolic events in patients with mitral stenosis (MS) in chronic atrial fibrillation (AF). Factors independently associated with LASEC, thrombi, and embolic events have been mainly investigated in patients with nonvalvular AF or inhomogeneous populations with rheumatic heart disease. Transesophageal and transthoracic echo studies were performed in 129 patients with MS in chronic AF. Previous embolic events were documented in 45 patients, 20 of them within 6 months, and 65 patients were receiving long-term anticoagulation. The intensity of LASEC and mitral regurgitation, the presence of thrombi and active LA appendage flow (peak velocities > or = 20 cm/s), and LA volume as well as other conventional echo-Doppler determinations were investigated in every patient. The prevalences of significant LASEC (degrees 3+ and 4+), thrombus, active LA appendage flow, and significant mitral regurgitation (>2+) were: 52% (67 patients), 29.5% (38 patients), 32% (41 patients), and 36% (47 patients), respectively. Multivariate analysis showed that decreasing mitral regurgitation severity, absence of active LA appendage flow, and mitral valve area were the independent correlates of LASEC (odds ratio [OR] 3.7, 5.4, and 0.17, respectively; all p <0.02). Active LA appendage flow and anticoagulant therapy were associated negatively, whereas the severity of LASEC was associated positively with the finding of LA thrombus (OR 9.6, 3.9, and 1.6, respectively; all p <0.05). The intensity of LASEC and previous anticoagulant therapy (OR 1.74 and 4.5, respectively; p <0.005) were the independent covariates of thrombi and/or recent embolic events. In conclusion, the severity of mitral regurgitation and lack of active LA appendage flow were, respectively, the strongest independent correlates of significant LASEC and thrombus in patients with MS in chronic AF. LASEC remains the cardiac factor most strongly associated with thrombus and/or recent embolic events in these patients.

Clinical and echocardiographic predictors of left atrial clot and spontaneous echo contrast in patients with severe rheumatic mitral stenosis: a prospective study in 200 patients by transesophageal echocardiography

The objective of this study was to prospectively investigate various clinical and echocardiographic variables to predict the left atrial and left atrial appendage clot and spontaneous echo contrast in patients with severe rheumatic mitral stenosis. We studied 200 consecutive patients (112 males and 88 females; mean age 29.6+/-9.6 years). Left atrial clot and spontaneous echo contrast were present in 26 and 53.5% of cases, respectively. There were no significant differences in the mitral valve area, mean transmitral diastolic gradient and left ventricular ejection fraction between patients with and without clot. Patients with clot were older (34.4+/-11.4 vs. 28.2+/-8.5 years, P<0.001), had longer duration of symptoms (41. 4+/-36.0 vs. 28.8+/-22.9 months, P<0.001), more frequent atrial fibrillation and spontaneous echo contrast (69.2 vs. 16.9%, P<0. 00001 and 76.9 vs. 45.3%, P<0.00001, respectively) and larger left atrial area and diameter (41.0+/-12.7 vs. 29.9+/-7.4 cm(2), P<0.00001 and 53.9+/-8.3 vs. 47.6+/-7.4 mm, P<0.0001, respectively) as compared to patients without clot. Similarly patients with spontaneous echo contrast were older (31+/-10.4 vs. 27.8+/-8.3 years, P<0.01), had more frequent atrial fibrillation (48.6 vs. 9.7%, P<0.0001), left atrial clot (37.4 vs. 12.9%, P<0.0001), larger left atrial area and diameter (37.6+/-11.2 vs. 28.1+/-6.7 cm(2), P<0.00001 and 52.2+/-8.3 vs. 45.9+/-6.5 mm, P<0.00001, respectively) and smaller mitral valve area (0.77+/-0.14 vs. 0.84+/-0.13 cm(2), P<0.01) as compared to patients without spontaneous echo contrast. There were no significant differences in the mean transmitral diastolic gradient and left ventricular ejection fraction. On multiple regression and discriminant function analysis, atrial fibrillation and left atrial area were independent predictors of left atrial clot formation. In a subgroup of patients with sinus rhythm, larger left atrial area and presence of spontaneous echo contrast were significantly associated with the presence of clot in left atrium and appendage. We conclude that in patients with severe mitral stenosis, the presence of atrial fibrillation and in the subgroup of the patients with sinus rhythm the presence of large left atrium (> or =40 cm(2)) and spontaneous echo contrast were associated with higher risk of clot formation in the left atrium and might be benefited by prophylactic anticoagulation.

Identification of echocardiographic "smoke" in a bench model with transcranial Doppler ultrasound

BACKGROUND AND PURPOSE

Spontaneous echo contrast in cardiac chamber has been indicated as a source of cerebral embolism. The nature of the echocardiographic smokelike signal is still not fully understood. This study was designed to regenerate spontaneous echo contrast and verify its thromboembolic characters in an in vitro model.

METHODS

Spontaneous echo contrast was reproduced in an expansion chamber under low flow conditions in a close circulation system. The spontaneous echo contrast was monitored and recorded with a 2-dimensional cardiosonography system and a transcranial Doppler device. Meanwhile, clinically commonly encountered embolic materials such as whole-blood clots, platelet aggregate-rich plasma, air bubbles, and 100-mL normal saline were injected into this monitored circuit. The differentiation of spontaneous echo contrast from emboli was performed by both visual observations of the echo images and offline Doppler signal intensity analysis. Average signal intensities produced by spontaneous contrast and injection of embolic materials and saline were compared. Furthermore, the effect of Doppler-detected flow velocity on generation of spontaneous contrast was also evaluated.

RESULTS

Spontaneous echo contrast was reproduced at low flow settings (90 to 120 mL/min) in this model. There was no significant difference in average signal intensity between the flow with spontaneous echo contrast and that without the echo (P=0.71). However, injection of embolic materials or normal saline did not generate smokelike image but caused much higher average signal intensity than the flow with spontaneous contrast (P<0.001). Injection of normal saline also increased average signal intensity.

CONCLUSIONS

Our results suggest that smokelike echo is a special echo phenomenon occurring at low flow situations and does not itself produce material capable of embolizing into the systemic circulation.