Integrated backscatter assessment of left atrial spontaneous echo contrast in chronic nonvalvular atrial fibrillation: relation with clinical and echocardiographic parameters

Clinical significance of aortic spontaneous echo contrast in patients with nonvalvular atrial fibrillation

BACKGROUND

Little is known about spontaneous echo contrast (SEC) in the descending aorta (DASEC), occurring with or without SEC in the left atrium (LASEC), in the presence of atrial fibrillation (AF). We examined the clinical significance of DASEC, including its relationship with LASEC, in patients with nonvalvular AF.

METHODS

Among 176 patients, 41 (23%) had DASEC and 51 (29%) had LASEC. The patients were divided into four groups based on the presence/absence of LASEC and DASEC, as Group A: no SEC (n = 107); Group B: only LASEC (n = 28); Group C: only DASEC (n = 18); and Group D: both types of SEC (n = 23). Clinical and echocardiographic parameters were compared between groups, and the possible determinants of DASEC were evaluated.

RESULTS

Age, sex, and CHA2 DS2 -VASc score were similar in the four groups. Group D was more likely to have an increased LA diameter, decreased left ventricular ejection fraction (LVEF), and low LA appendage velocity compared to Group A. Group C had a smaller LA diameter and a higher appendage velocity than Group B. Multivariate logistic regression analysis, with age ≥75 years, female sex, LASEC, LVEF < 50%, and presence of DA plaques included as covariates, showed that LASEC (OR 4.22, 95% CI 1.92-9.26, p < .001) and LVEF < 50% (OR 2.70, 95% CI 1.12-6.52, p = .027) were significant determinants of DASEC. The prevalence of DASEC increased with increasing LASEC severity in order of none (13%), mild (28%), and dense (50%) (p < .001).

CONCLUSIONS

In nonvalvular AF patients, DASEC is common, and it partly originates from LASEC, particularly in the presence of LV systolic dysfunction.

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.

Left atrial spontaneous echo contrast: relationship with clinical and echocardiographic parameters

Spontaneous echo contrast (SEC) indicates blood stasis in cardiac chambers and major vessels, and is a known precursor of thrombus formation. Transesophageal echocardiography plays a pivotal role in detecting and grading SEC in the left atrial (LA) cavity. Assessing LA SEC can identify patients at increased risk for thromboembolic events. LA SEC also develops in patients who have sinus rhythm, especially in those with heart failure. Detection of LA SEC is not uncommon in subjects who have multiple cardiovascular comorbidities, although mechanisms behind this association are not fully understood. In patients with atrial fibrillation, the role of mitral regurgitation in counteracting LA SEC and subsequent thromboembolism is controversial. Moreover, alterations of blood coagulability and elevated levels of certain biological markers in the blood contribute to occurrence of LA SEC. This review describes the pathogenesis and assessment of SEC, in addition to the relationship between LA SEC and clinical, biological and echocardiographic parameters.

Role of transesophageal echocardiography guided cardioversion in patients with atrial fibrillation, previous left atrial thrombus and effective anticoagulation

AIMS

The value of transesophageal echocardiography (TEE) to prevent cardioversion-related thromboembolic events in patients with atrial fibrillation (AF) and left atrial (LA) thrombus is unclear. We compared the embolic risk associated with a strategy of follow-up TEE-guided direct-current cardioversion (DCCV) with that of blind DCCV in patients with AF, pre-existing LA thrombus and effective anticoagulation.

METHODS AND RESULTS

We identified 67 subjects with TEE-documented LA appendage thrombi from a total of 520 consecutive patients with symptomatic non-rheumatic AF who were referred to us for elective DCCV. All patients received at least 4 weeks of effective warfarin therapy (target international normalized ratio, 2 to 3) before and after DCCV. At time of DCCV, 20 patients had TEE and 47 did not. There were no clinical and echocardiographic differences between the two groups. Thrombus resolution was documented in 18 (90%) patients. After a median follow-up of 4 weeks, two transient ischemic attacks were observed in patients who were blindly cardioverted and one in patients belonging to the TEE group. Sinus rhythm was documented at the time of each thromboembolic event. By multiple logistic regression analysis the TEE strategy was not associated with lower risk of thromboembolism as compared to blind DCCV (odds ratio 1.37; 95% confidence interval, 0.16% to 15.86%; p=0.20).

CONCLUSION

In patients with AF, LA thrombus and effective anticoagulation, there is no difference in the risk of clinical thromboembolism between DCCV with or without follow-up TEE. Benefits of warfarin are related to thrombus resolution and prevention of new thrombus formation.

Comparison of frequency of thromboembolic events and echocardiographic findings in patients with chronic nonvalvular atrial fibrillation and coarse versus fine electrocardiographic fibrillatory waves

In patients with nonvalvular atrial fibrillation, the electrocardiographic fibrillatory wave reflects the structural and electrical remodeling of the atria. This study examined whether the fibrillatory wave amplitude could predict the risk of thromboembolism and demonstrated that this amplitude was related to the duration of atrial fibrillation. We also showed that the presence of fine fibrillatory waves (<1 mm in amplitude) could predict the thromboembolic potential in patients with chronic nonvalvular atrial fibrillation.

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.

Role of transesophageal echocardiography in the prediction of thromboembolism in patients with chronic nonvalvular atrial fibrillation

The purpose of this study was to determine whether parameters derived from transesophageal echocardiography (TEE) could predict thromboembolism in patients with chronic nonvalvular atrial fibrillation (AF). Eighty-nine patients, mean age 66+/-9 years, who underwent TEE in 1996 to 1999 were studied. The clinical endpoint was a thromboembolic event, including transient ischemic attack (TIA). Sixty-seven patients (75%) were anticoagulated with warfarin after TEE. After a follow-up period of 29+/-10 months, 1 patient died suddenly, 4 had a thromboembolism, and 3 had a TIA; the annual embolic event rate was 3.3%. Left atrial appendage (LAA) thrombus (86% vs 17%, p<0.001), LAA dysfunction (LAA velocity <20 cm/s; 71% vs 25%, p=0.009), and severe LA spontaneous echo contrast (29% vs 2%, p=0.002) were more prevalent in patients with an embolic event than in those without. In patients with LAA thrombus, the annual event rate was 11% as compared with 1.2% in those without (p=0.004). On the Cox proportional hazards model analysis, LAA thrombus (chi-square 7.0, p=0.008), severe LA spontaneous echo contrast (chi-square 7.0, p=0.008), and LAA dysfunction (chi-square 5.9, p=0.015) were significantly related to thromboembolism. Multivariate analysis revealed that LAA thrombus (chi-square 5.5, p=0.019) and LAA dysfunction (chi-square 4.0, p=0.045) were the independent predictors. In conclusion, TEE parameters, particularly the presence of LAA thrombus, can be used to assess thromboembolic potential in patients with chronic nonvalvular AF.