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

Evolution of Coagulation and Platelet Activation Markers After Transcatheter Edge-to-Edge Mitral Valve Repair

Background/Objectives: The recommendations for antithrombotic therapy after transcatheter edge-to-edge mitral valve repair (TEER) are empirical, and the benefit of antiplatelet (APT) or anticoagulation therapy (ACT) remains undetermined. The study sought to investigate the degree and the timing of coagulation and platelet marker activation after TEER. Methods: This was a prospective study including 46 patients undergoing TEER. The markers of coagulation activation, namely prothrombin fragment 1 + 2 (F1 + 2) and thrombin-antithrombin III (TAT), and the markers of platelet activation, namely soluble P-Selectin and soluble CD-40 ligand (sCD40L), were measured at baseline, 24 h, 1 month, and 1 year after TEER. Results: At discharge, 20 (43%) patients received APT (single: 16, dual: 4), 24 (52%) received ACT, and 2 (4%) had both single APT and ACT. Levels of F1 + 2 and TAT significantly increased at 24 h post TEER (both p < 0.001), rapidly returning to baseline levels at 1 month. However, levels of F1 + 2 and TAT remained higher at 1 month in patients without ACT compared to patients with ACT (respectively, 303.1 vs. 148.1 pmol/L; p < 0.001 and 4.6 vs. 3.0 µg/L; p = 0.020), with a similar trend at 1 year. Levels of soluble P-selectin and sCD40L remained stable at all times after TEER (respectively, p = 0.071 and p = 0.056), regardless of the APT. Conclusions: TEER is associated with an acute activation of the coagulation system, with no increase in platelet activation markers. Hence, the use of dual APT is questionable in this population. Our results raise the hypothesis that the optimal antithrombotic therapy after TEER could be short-term ACT over APT. Further larger studies are warranted.

Modified Haller Index is inversely associated with asymptomatic status in atrial fibrillation patients undergoing electrical cardioversion: a preliminary observation

BACKGROUND

No previous study evaluated the possible influence of chest wall conformation on symptoms perception in atrial fibrillation (AF) patients candidates for electrical cardioversion (ECV). We aimed at evaluating the anthropometric and clinical characteristics of patients with persistent AF undergoing ECV, categorized according to the presence or absence of symptoms.

METHODS

This study retrospectively analyzed a series of persistent AF patients scheduled for early ECV who underwent pre-procedural clinical evaluation, MHI (the ratio of chest transverse diameter over the distance between sternum and spine) assessment, transthoracic and transesophageal echocardiography implemented with strain analysis of both left atrium and left atrial appendage. Thromboembolic risk and burden of comorbidities were assessed by CHA2DS2-VASc Score and Charlson Comorbidity Index (CCI), respectively. The independent predictors of "asymptomatic AF" were assessed.

RESULTS

A total of 25 asymptomatic and 90 symptomatic AF patients were retrospectively examined. Compared to symptomatic AF patients, those asymptomatic were significantly older (78.4±3.8 vs. 71.0±7.7 years, P<0.001), predominantly males (84 vs. 44.4%, P<0.001), with significantly lower MHI (2.0±0.1 vs. 2.4±0.1, P<0.001), higher CHA2DS2-VASc Score (5.8±1.1 vs. 3.6±1.1, P<0.001) and CCI (6.8±1.4 vs. 2.3±0.9, P<0.001), and greater impairment in biventricular systolic function and atrio-auricolar myocardial strain indices. On multivariate logistic regression analysis, CHA2DS2-VASc Score (OR=2.65, 95% CI: 1.53-4.60) and CCI (OR=2.36, 95% CI: 1.16-4.66) were linearly associated with the endpoint "asymptomatic AF," whereas MHI (OR 0.76, 95% CI 0.59-0.97) was inversely associated with the asymptomatic status. A MHI <2.2 was the best cut-off for detecting asymptomatic AF patients.

CONCLUSIONS

MHI is inversely associated with asymptomatic status in persistent AF patients undergoing ECV. MHI assessment might represent an innovative practical approach to AF patients.

Turbulent blood dynamics in the left heart in the presence of mitral regurgitation: a computational study based on multi-series cine-MRI

In this work, we performed a computational image-based study of blood dynamics in the whole left heart, both in a healthy subject and in a patient with mitral valve regurgitation. We elaborated multi-series cine-MRI with the aim of reconstructing the geometry and the corresponding motion of left ventricle, left atrium, mitral and aortic valves, and aortic root of the subjects. This allowed us to prescribe such motion to computational blood dynamics simulations where, for the first time, the whole left heart motion of the subject is considered, allowing us to obtain reliable subject-specific information. The final aim is to investigate and compare between the subjects the occurrence of turbulence and the risk of hemolysis and of thrombi formation. In particular, we modeled blood with the Navier-Stokes equations in the arbitrary Lagrangian-Eulerian framework, with a large eddy simulation model to describe the transition to turbulence and a resistive method to manage the valve dynamics, and we used a finite element discretization implemented in an in-house code for the numerical solution.

Stroke in mitral valve prolapse: risk factors and left atrial function in cryptogenic versus non-cryptogenic ischemic subtypes

Background and purpose

Mitral valve prolapse (MVP) has been associated with an increased risk of ischemic stroke. Older age, thicker mitral leaflets, and significant mitral regurgitation (MR) leading to atrial fibrillation have been traditionally considered risk factors for ischemic stroke in MVP. However, specific risk factors for MVP-stroke subtypes are not well defined. The aim of this study is to evaluate clinical and echocardiographic parameters, including left atrial (LA) function, in MVP with cryptogenic (C) vs. non-cryptogenic (NC) stroke.

Methods

In this case-control matched study, MVPs were identified in consecutive echocardiograms obtained after a stroke from January 2013 to December2016 at the University of California, San Francisco. MVP was defined as leaflet displacement ≥2 mm in the parasternal long-axis view at end-systole. Age/gender matched MVPs without stroke and healthy controls without MVP were also identified. We analyzed LA end-systolic/diastolic volume index, emptying fraction (LAEF), function index (LAFI), and global longitudinal strain in all MVPs and controls. We also measured left ventricular (LV) volume indexes, mass index, ejection fraction (EF), degree of MR and leaflet thickness.

Results

We identified a total of 30 MVPs (age 70 ± 12, 50% females) with stroke (11 with C- and 19 with NC-stroke), 20 age/gender matched MVPs without a stroke and 16 controls. MVPs without stroke had lower BMI, less hypertension but more MR (≥moderate in 45% vs. 17%), more abnormal LA function (lower LAEF, LAFI) and larger LV volumes/mass (all p < 0.05) when compared to MVPs with stroke. Leaflet thickness was overall mild (<3 mm) and similar in the 2 groups. Within the MVP stroke group, NC-stroke had higher BMI, more hypertension and more atrial fibrillation compared to C-stroke. In the variables tested, patients with C-stroke did not differ from controls.

Conclusions

MVP-related MR may be protective against stroke despite abnormal LA function. Risk of NC-stroke in MVP is related to common stroke risk factors rather than mitral valve leaflet thickness. The etiology of C-stroke in MVP warrants further studies.

Left Atrial Thrombus-Are All Atria and Appendages Equal?

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

Frequency and Clinical Significance of Atrial Cavities in situ Thrombosis: A Large-Scale Study and Literature Review

Background

Atrial tachyarrhythmias are the main cause of atrial thrombosis, and are usually in the left appendage. The prevalence and causes of endocavitarian thrombosis have not been investigated in recent large-scale studies. Aim of our work was to describe the epidemiology, the clinical characteristics and predisposing factors of "extra-appendicular" atrial thrombosis and to report a systematic review of recent literature.

Methods and Results

5,862 consecutive adult patients referred to a transesophageal echocardiographic exam, were enrolled. A total of 175 subjects with Atrial Thrombosis were found with a prevalence of 2.98%; among those 22 was found in left (0.38%) and 2 in the right (0.03%) atrium. Among the 22 patients with left atrial thrombosis, 8 were associated with prosthetic valves, 4 with mitral stenosis and the remaining with hypercoagulative conditions (cancer, septic shock, eosinophilic pneumonia, cardiogenic shock and warfarin under-dosage in permanent atrial fibrillation and decompensated heart failure). Cancer was associated in one of the two patients with a right atrial clot. The review of the literature from 2000 to December 2019 revealed conflicting results of 48 case reports of atrial cavity thrombosis; pooling this data proved the rarity of extra-appendage thrombosis and confirmed its association with a valvular heart disease or a systemic hypercoagulable state.

Conclusions

Atrial "extra-appendage" thrombosis is a rare condition usually associated to "valvular" atrial fibrillation (such as prosthetic valves and mitral stenosis). A minority, but significant, cases are secondary to a thrombophilic conditions. In absence of valvular heart disease an underlying condition should be sought.

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.

Left Atrial Thrombus-Are All Atria and Appendages Equal?

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

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.

Sensitivity Analysis of In Silico Fluid Simulations to Predict Thrombus Formation after Left Atrial Appendage Occlusion

Atrial fibrillation (AF) is nowadays the most common human arrhythmia and it is considered a marker of an increased risk of embolic stroke. It is known that 99% of AF-related thrombi are generated in the left atrial appendage (LAA), an anatomical structure located within the left atrium (LA). Left atrial appendage occlusion (LAAO) has become a good alternative for nonvalvular AF patients with contraindications to anticoagulants. However, there is a non-negligible number of device-related thrombus (DRT) events, created next to the device surface. In silico fluid simulations can be a powerful tool to better understand the relation between LA anatomy, haemodynamics, and the process of thrombus formation. Despite the increasing literature in LA fluid modelling, a consensus has not been reached yet in the community on the optimal modelling choices and boundary conditions for generating realistic simulations. In this line, we have performed a sensitivity analysis of several boundary conditions scenarios, varying inlet/outlet and LA wall movement configurations, using patient-specific imaging data of six LAAO patients (three of them with DRT at follow-up). Mesh and cardiac cycle convergence were also analysed. The boundary conditions scenario that better predicted DRT cases had echocardiography-based velocities at the mitral valve outlet, a generic pressure wave from an AF patient at the pulmonary vein inlets, and a dynamic mesh approach for LA wall deformation, emphasizing the need for patient-specific data for realistic simulations. The obtained promising results need to be further validated with larger cohorts, ideally with ground truth data, but they already offer unique insights on thrombogenic risk in the left atria.

Mechanical concordance between left atrium and left atrial appendage in nonvalvular atrial fibrillation: can it be exploited to avoid transesophageal echocardiography prior to electrical cardioversion during Covid-19 pandemic?

Transesophageal echocardiography (TEE) is the gold standard for assessing left atrial appendage (LAA) mechanic and thrombosis (LAAT); however, TEE is a high-risk procedure for viral transmission during coronavirus disease 2019 (COVID-19) pandemic. We investigated whether deformation indices of left atrium (LA) at transthoracic echocardiography (TTE) correlate with those of LAA assessed by TEE in nonvalvular atrial fibrillation (NVAF) patients undergoing electrical cardioversion (ECV). Consecutive patients with NVAF of ≥ 48 h or unknown duration, who underwent TEE and TTE at our Institution before ECV were retrospectively investigated. Standard echo-Doppler and LA and LAA myocardial strain and strain rate parameters were analyzed. A total of 115 NVAF patients (71.3 ± 8.1 yr/o, 59.1% men) were included: LAAT was diagnosed in 25 (21.7%) patients. Compared to patients without LAAT, those with LAAT had significantly higher CHA₂DS₂-VASc Risk score (4.5 ± 1.4 vs. 3.5 ± 1.1, p < 0.001), and lower ejection fraction (46.0 ± 14.8 vs. 57.6 ± 8.6%, p < 0.001). In LAAT patients, global strain of LA (8.7 ± 2.6 vs. 16.3 ± 4.5%, p < 0.001) and LAA (7.0 ± 1.7 vs. 11.7 ± 2.0%, p < 0.001) was significantly reduced compared to non-LAAT patients. A close relationship between left atrial strain reservoir (LASr) and LAA-global strain was demonstrated (r = 0.81). By univariable analysis, CHA₂DS₂-VASc Risk Score (OR 2.01, 95%CI 1.34–3.00), NT-proBNP (OR 1.36, 95%CI 1.19–1.54), ejection fraction (OR 0.92, 95%CI 0.88–0.96), E/e’ ratio (OR 2.07, 95%CI 1.51–2.85), and LASr (OR 0.39, 95%CI 0.25–0.62) were strongly associated with LAAT presence at TEE. By multivariable analysis, only LASr (OR 0.40, 95%CI 0.24–0.70) retained statistical significance. ROC curve analysis revealed that an LASr cut-off value ≤ 9.3% had 98.9% sensibility and 100% specificity to identify LAAT by TEE (AUC = 0.98). In patients with NVAF of ≥ 48 h or unknown duration, scheduled to undergo ECV, LA deformation assessment by TTE might substitute invasive measurement of LAA function by TEE, simplifying diagnostic approach and possibly contributing to reduce COVID-19 infection diffusion.

Effect of Mitral Regurgitation on Thrombotic Risk in Patients With Nonrheumatic Atrial Fibrillation: A New CHA2DS2-VASc Score Risk Modifier?

The current study assessed the effect of mitral regurgitation (MR) on thrombotic risk in nonrheumatic atrial fibrillation (AF). AF carries a thrombotic risk related to left atrial blood stasis. The prevalence of atrial thrombosis, defined as the presence of left atrial appendage thrombus and/or left atrial spontaneous echo contrast grade >2, was determined in 686 consecutive nonrheumatic AF patients without (adequate) anticoagulation scheduled for transesophageal echocardiography before electrical cardioversion and was related to the severity of MR adjusted for the CHA₂DS₂-VASc score. A total of 103 (15%) patients had severe MR, 210 (31%) had moderate MR, and 373 (54%) had no-mild MR; the median CHA₂DS₂-VASc score was 3.0 (interquartile range 2.0 to 4.0). Atrial thrombosis was observed in 118 patients (17%). The prevalence of atrial thrombosis decreased with increasing MR severity: 19.9% versus 15.2% versus 11.6% for no-mild, moderate, and severe MR, respectively (p value for trend = 0.03). Patients with moderate and severe MR had a lower risk of atrial thrombosis than patients with no-mild MR, with adjusted odds ratios of 0.51 (95% confidence interval 0.31 to 0.84) and 0.24 (95% confidence interval 0.11 to 0.49), respectively. The protective effect of MR was present across all levels of the CHA₂DS₂-VASc risk score and the presence of moderate-severe MR in patients with an intermediate CHA₂DS₂-VASc score (2 to 3) lowered the atrial thrombotic risk to the level of patients with a low CHA₂DS₂-VASc score (0 to 1). In conclusion, our data show that the presence of MR attenuated the atrial thrombotic risk by more than 50% in patients with nonrheumatic AF.

Echocardiographic Findings in Patients with Atrial Fibrillation in a Tertiary Care Center of Nepal: A Descriptive Cross-sectional Study

Introduction:

Atrial fibrillation is the most prevalent supraventricular arrhythmia responsible for the large morbidity and mortality burden worldwide. There are various causes of atrial fibrillation that may affect the prognosis of patients. This study was intended to determine different echocardiographic findings in patients with atrial fibrillation in a tertiary care center.

Methods:

A descriptive cross-sectional study was conducted at Manmohan Cardiothoracic Vascular and Transplant Center, Institute of Medicine, among 175 patients with atrial fibrillation admitted in the cardiology department from June 2017 to October 2018. It was approved by the Institutional Review Board of the Institute of Medicine (Ref.:411(6-11-E)2/073/074). Convenience sampling was used. Statistical analysis was done using Statistical Package for Social Sciences version 21.0.

Results:

A total of 175 patients with atrial fibrillation were enrolled where Rheumatic heart disease 68 (38.9%) was the leading cause in which 54 (79.4%) had mitral valve lesion, 1 (1.5%) had aortic valve lesion and rest had a combination of both. The mixed lesion of mitral stenosis and mitral regurgitation was the commonest. The left atrium size was larger in valvular atrial fibrillation (47.29±6.651mm). The left ventricular systolic dysfunction was seen more in non-valvular atrial fibrillation. The commonest site of thrombus formation was left atrium 7 (63.6%).

Conclusions:

Atrial fibrillation was common in rheumatic heart disease, especially mixed lesions of mitral stenosis and regurgitation. Valvular atrial fibrillation had a larger left atrium. The thrombus was seen in mitral stenosis and left ventricular systolic dysfunction. The left atrium size and left ventricular ejection fraction were associated with the occurrence of atrial fibrillation.

Atrial Fibrillation and Mitral Regurgitation: Clinical Performance of Direct Oral Anticoagulants in a Real-World Setting

BACKGROUND

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is frequently present in patients with mitral regurgitation (MR). Currently, there is a lack of real-world evidence specifically addressing the clinical performance of direct oral anticoagulants (DOACs) in patients with AF and concomitant MR. Therefore, the aim of the present study was to assess the efficacy and safety profile of DOACs therapy in patients with AF and MR.

METHODS

Data for this study were sourced from the Atrial Fibrillation Research Database in the Department of Cardiology at Monaldi Hospital. The database was queried for AF patients with MR who were prescribed DOACs therapy. The primary safety outcome was defined as the annual incidence rate of major bleeding events and the primary effectiveness outcome as the annual incidence rate of all events classified as ischemic stroke, transient ischemic attacks, and systemic embolisms.

RESULTS

Consecutive AF patients with concomitant mild to severe MR who received DOACs therapy (n = 259) were included. Patients were dichotomized in 2 groups according to MR severity: a mild-to-moderate group (MR 1-2+; n = 151) and a moderate-to-severe group (MR 3-4+; n = 108). The incidence rate of major bleedings was significantly higher in MR 3-4+ group (3.92%) compared with the MR 1-2+ group (1.18%; hazard ratio [HR]: 3.2; 95% CI: 1.4-7.3; P = .0059). The incidence rate of thromboembolic events between MR 3-4+ group (0.66%) and MR 1-2+ group (0.62%) was not significantly different (HR: 0.75; P = .823).

CONCLUSIONS

In the present study, there was no difference in the efficacy profile of DOACs between AF patients with mild-to-moderate and moderate-to-severe MR. Considering the increased bleeding risk, a close and careful follow-up should be warranted for patients with moderate-to-severe MR.