The Refinement of Risk Stratification for Atrial Thrombus or Spontaneous Echo Contrast in Nonvalvular Atrial Fibrillation

Left atrial enlargement and high uric acid level are risk factors for left atrial thrombus or dense spontaneous echo contrast in atrial fibrillation patients with low to moderate embolic risk assessed by CHA2DS2-VASC score

Aims

To investigate the correlation and predictive value of left atrial diameter and blood uric acid levels with the occurrence of left atrial thrombus or dense spontaneous echo contrast in atrial fibrillation patients with low to moderate CHA₂DS₂-VASc scores.

Methods and results

A total of 849 inpatients diagnosed with atrial fibrillation who had low to moderate CHA₂DS₂-VASc scores and complete transesophageal echocardiography were included in this study. Among them, 66 patients had left atrial thrombus or dense spontaneous echo contrast. When different models were used to correct other known risk factors, acid levels and abnormal left atrial diameter were identified as additional risk factors for left atrial thrombus or dense spontaneous echo contrast. The incidence of left atrial thrombus or dense spontaneous echo contrast was higher in patients with abnormal serum uric acid levels than in the control group (12.4% vs. 5.6%, p < 0.05), and this difference persisted after correcting the baseline data with propensity score matching (10.6% vs. 4.1%, p < 0.05). Abnormal left atrial diameter was another risk factor suggested by regression analysis, with an increased incidence of left atrial thrombus or dense spontaneous echo contrast in the abnormal left atrial diameter group compared to the control group, both before (18.0% vs. 3.5%, p < 0.05) and after (15.5% vs. 5.2%, p < 0.05) propensity score matching. The best predictive value was obtained by adding both abnormal serum uric acid levels and abnormal left atrial diameter.

Conclusion

Left atrial enlargement and high uric acid levels increase the risk of left atrial thrombus or dense spontaneous echo contrast in atrial fibrillation patients with low to moderate CHA₂DS₂-VASc scores.

Predicting a decrease in left atrial appendage flow velocity using left atrial diameter and CHA2DS2-VASc score in patients with non-valvular atrial fibrillation

BACKGROUND

Left atrial (LA) appendage flow velocity (LAAFV) is a classic but invasive predictor of thromboembolic events in patients with atrial fibrillation (AF). We aimed to explore the usefulness of LA diameter (LAD) combined with CHA₂DS₂-VASc score, which is easily available and non-invasive, as a novel score for predicting a decrease in LAAFV in non-valvular AF (NVAF).

METHODS

In total, 716 consecutive NVAF patients who underwent transesophageal echocardiography were divided into the decreased LAAFV (< 0.4 m/s) and preserved LAAFV (≥ 0.4 m/s) groups.

RESULTS

The decreased LAAFV group had a larger LAD and a higher CHA₂DS₂-VASc score than the preserved LAAFV group (P < 0.001). Multivariate linear regression indicated that brain natriuretic peptide (BNP) concentration, persistent AF, LAD, and CHA₂DS₂-VASc score were remained inversely associated with LAAFV. Moreover, multivariate logistic regression revealed that BNP concentration (odds ratio [OR] 1.003, 95% confidence interval [CI] 1.001-1.005, P = 0.003), persistent AF (OR 0.159, 95% CI 0.102-0.247, P < 0.001), and LAD (OR 1.098, 95% CI 1.049-1.149, P < 0.001) were independent factors for a decrease in LAAFV. A novel score, LAD combined with CHA₂DS₂-VASc score, was more accurate for predicting a decrease in LAAFV among NVAF patients (area under the curve was 0.733).

CONCLUSION

Enlarged LAD was independent risk factor for a decrease in LAAFV among NVAF patients. LAD combined with CHA₂DS₂-VASc score enhanced the predictive ability for a decrease in LAAFV among NVAF patients.

Medical record data-enabled machine learning can enhance prediction of left atrial appendage thrombosis in nonvalvular atrial fibrillation

BACKGROUND

As a major complication of non-valvular atrial fibrillation (NVAF), left atrial appendage (LAA) thrombosis is associated with cerebral ischemic strokes, as well as high morbidity. Due to insufficient incorporation of risk factors, most current scoring methods are limited to the analysis of relationships between clinical characteristics and LAA thrombosis rather than detecting potential risk. Therefore, this study proposes a clinical data-driven machine learning method to predict LAA thrombosis of NVAF.

METHODS

Patients with NVAF from January 2014 to June 2022 were enrolled from Southwest Hospital. We selected 40 variables for analysis, including demographic data, medical history records, laboratory results, and the structure of LAA. Three machine learning algorithms were adopted to construct classifiers for the prediction of LAA thrombosis risk. The most important variables related to LAA thrombosis and their influences were recognized by SHapley Addictive exPlanations method. In addition, we compared our model with CHADS2 and CHADS2-VASc scoring methods.

RESULTS

A total of 713 participants were recruited, including 127 patients with LAA thrombosis and 586 patients with no obvious thrombosis. The consensus models based on Random Forest and eXtreme Gradient Boosting LAA thrombosis prediction (RXTP) achieved the best accuracy of 0.865, significantly outperforming CHADS2 score and CHA2DS2-VASc score (0.757 and 0.754, respectively). The SHAP results showed that B-type natriuretic peptide, left atrial appendage width, C-reactive protein, Fibrinogen and estimated glomerular filtration rate are closely related to the risk of LAA thrombosis in nonvalvular atrial fibrillation.

CONCLUSIONS

The RXTP-NVAF model is the most effective model with the greatest ROC value and recall rate. The summarized risk factors obtained from SHAP enable the optimization of the treatment strategy, thereby preventing thromboembolism events and the occurrence of cardiogenic ischemic stroke.

Refinement of CHADS2 and CHA2DS2-VASc scores predict left atrial thrombus or spontaneous echo contrast in nonvalvular atrial fibrillation patients

Objective

To investigate the risk factors of left atrial thrombus (LAT)/spontaneous echo contrast (SEC) in patients with nonvalvular atrial fibrillation (AF).

Methods

This retrospective study analysed the data from consecutive patients with nonvalvular AF that underwent transoesophageal echocardiography. Logistic regression analysis was performed to identify risk factors of LAT/SEC. Receiver operating characteristic curve analysis was undertaken compare the new scales with CHADS2 and CHA2DS2-VASc scores.

Results

A total of 558 patients with AF were included in the study. LAT/SEC was detected in 137 (24.6%) patients. The independent risk factors of LAT/SEC beyond CHADS2 or CHA2DS2-VASc scores included non-paroxysmal AF and left atrial diameter >37.5 mm. These two variables were added into the CHADS2 or CHA2DS2-VASc score to build new scales. Areas under the curve for the new scales based on CHADS2 and CHA2DS2-VASc scores were significantly higher than the CHADS2 or CHA2DS2-VASc score both in the overall study cohort and in patients at a high risk of thromboembolism.

Conclusions

Non-paroxysmal AF and increased left atrial diameter beyond the CHADS2 or CHA2DS2-VASc score were independent risk factors of LAT/SEC and may help to improve the current risk stratification, especially for patients with nonvalvular AF at a high risk of thromboembolism.

The Relationship between Uric Acid and the Development, Complication, and Prognosis of Atrial Fibrillation: The Views from a Clinical Study

A large number of studies suggest that uric acid (UA) is related to the occurrence, complications, and prognosis of atrial fibrillation (AF). However, the guidelines did not clearly elaborate on this issue. The current research results need to be summarized to analyze the association between UA and AF. This study found that in the current clinical research on the relationship between UA and AF, studies mainly focus on the development or complications of AF. A lot of repetitive work does not deepen awareness of this question. In contrast, studies investigating the effects of UA-lowering therapy on the management of AF are limited. The only reports deny the protective effect of UA-lowering therapy. For now, we suggest that UA is close to the occurrence and progression of AF; therefore, it may have important significance as a clinical marker. The role of UA-lowering therapy in the management of AF is one of the next key issues to be explored. It will be a meaningful topic to focus on the latest research on AF ablation and to conduct a secondary analysis to explore the prognostic impact of UA on the latest treatment methods for AF. Multiomics techniques may allow us to have a deeper understanding of the role of UA in AF management in the future.

A Review of Biomarkers for Ischemic Stroke Evaluation in Patients With Non-valvular Atrial Fibrillation

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia worldwide and results in a significantly increased ischemic stroke (IS) risk. IS risk stratification tools are widely being applied to guide anticoagulation treatment decisions and duration in patients with non-valvular AF (NVAF). The CHA₂DS₂-VASc score is largely validated and currently recommended by renowned guidelines. However, this score is heavily dependent on age, sex, and comorbidities, and exhibits only moderate predictive power. Finding effective and validated clinical biomarkers to assist in personalized IS risk evaluation has become one of the promising directions in the prevention and treatment of NVAF. A number of studies in recent years have explored differentially expressed biomarkers in NVAF patients with and without IS, and the potential role of various biomarkers for prediction or early diagnosis of IS in patients with NVAF. In this review, we describe the clinical application and utility of AF characteristics, cardiac imaging and electrocardiogram markers, arterial stiffness and atherosclerosis-related markers, circulating biomarkers, and novel genetic markers in IS diagnosis and management of patients with NVAF. We conclude that at present, there is no consensus understanding of a desirable biomarker for IS risk stratification in NVAF, and enrolling these biomarkers into extant models also remains challenging. Further prospective cohorts and trials are needed to integrate various clinical risk factors and biomarkers to optimize IS prediction in patients with NVAF. However, we believe that the growing insight into molecular mechanisms and in-depth understanding of existing and emerging biomarkers may further improve the IS risk identification and guide anticoagulation therapy in patients with NVAF.

Uric Acid-An Emergent Risk Marker for Thrombosis?

Hyperuricemia is nowadays an established cardiovascular risk factor. Experimental studies linked elevated serum uric acid (SUA) levels with endothelial dysfunction (ED), inflammation, and prothrombotic state. The purpose of this review is to summarize the current evidence that emphasizes the possible role of uric acid as a biomarker for a prothrombotic state. A large number of clinical trials correlated SUA levels with both incident and recurrent cases of venous thromboembolism (VTE), independent of other confounding risk factors. Moreover, increased SUA levels may be an important tool for the risk stratification of patients with pulmonary embolism (PE). Left atrial thrombosis was correlated with high SUA levels in several studies and its addition to classical risk scores improved their predictive abilities. In patients with acute myocardial infarction (MI), hyperuricemia was associated with increased mortality, and the idea that hyperuricemia may be able to act as a surrogate to unstable coronary plaques was advanced. Finally, SUA was correlated with an increased risk of thromboembolic events in different systemic diseases. In conclusion, uric acid has been considered a marker of a thrombotic milieu in several clinical scenarios. However, this causality is still controversial, and more experimental and clinical data is needed.

New perspective on the risk markers for left atrial thrombosis in patients with atrial fibrillation

BACKGROUND

Anticoagulant therapy is one of the important aspects of atrial fibrillation (AF) management, which can effectively reduce the formation of left atrial thrombosis (LAT) and the occurrence of embolic events. The CHA2DS2-VASc score is a commonly used risk assessment tool for embolic events, and it has guiding significance for anticoagulant therapy. However, a large number of recent studies have clearly shown that some of the markers that are not included in the score affect the formation of LAT.

OBJECTIVE

This single-center study probed for risk markers for LAT by analyzing the clinical features of patients who experienced AF.

METHODS

We reviewed patients with AF who had undergone a transesophageal echocardiography exam over the past 6 years and used binary logistic regression analysis to identify risk markers other than CHA2DS2-VASc score. For the risk markers found, the propensity score matching (PSM) was used to further evaluate whether it was an independent risk marker for LAT. The newly discovered markers were added to the score, and receiver operating characteristic analysis was used to evaluate whether the ability of the model to predict LAT was improved.

RESULTS

A total of 2246 patients were included in the study. In total, 838 of them were anticoagulated (314 with rivaroxaban, 57 with dabigatran, and 467 with warfarin) and 30 patients (1.33%) had LAT. Regression analysis revealed abnormal uric acid metabolism (abUA) and obesity were risk markers for LAT. Further PSM analysis found that abUA was an independent risk marker for LAT. After including abUA, the CHA2DS2-VASc score was more accurate for LAT prediction (area under the curve difference is 0.0651, 95% confidence interval: 0.0247, 0.1050, Z = 3.158, P = 0.0016).

CONCLUSIONS

AbUA is an independent risk marker for LAT. After considering abUA, the CHA2DS2-VASc score for LAT is more accurate.

Low Consultation Rate of General Population with Atrial Fibrillation

In order to prevent ischemic stroke, it is important to identify and treat patients with atrial fibrillation (AF) who do not consult a doctor in a medical institution. The aim of this study was to determine the consultation rate at medical institutions for patients with AF in group medical examinations conducted in a city in western Japan. Of 6101 examinees of group medical examinations (40 years of age or older) conducted in Ibara City, Okayama Prefecture, Japan, from 2012 to 2014, 4338 participants (71.1%) who were evaluated by electrocardiogram (ECG) gave written informed consent and responded to surveys in the form of questionnaires through a personal interview conducted by nurses were included in the Ibara-AF study. A cumulative total of 82 subjects were diagnosed as having AF by ECG (prevalence of AF = 1.89%), and 51 individuals had AF during the three-year period.15 (29.4%) of the 51 patients with AF did not regularly visit medical institutions. Among them, 46.7% (n = 7) and 53.3% (n = 8) of the patients were symptomatic and asymptomatic, respectively, and 73.3% of the patients had a CHADS₂ score of more than one point. There were no significant differences in patients' characteristics between regular and non-regular visit groups. In conclusion, about one-third of the patients with AF did not regularly see a doctor in a medical institution and most of them had a CHADS₂ score of more than one point in a Japanese rural area. Educating the public about the risks of AF is required.

Young Patients with Unknown Stroke and Little P Wave in ECG

Here we report two young patients with atrial fibrillation/atrial flutter complicated with cardiogenic cerebral embolism. Electrophysiological study revealed a large area of low-voltage zone or area of electric silence in both sides of the atrium during restoration of sinus rhythm, and the echocardiogram showed loss of mechanical function of the atrium. The electrical-mechanical dysfunction of the atrium was considered to be the cause of embolic event in this type of patient who was "very low" stroke risk atrial fibrillation or atrial flutter. The idiopathic, fibrotic atrial cardiomyopathy may be underlying in these patients.

Resting Heart Rate and the Risk of Atrial Fibrillation

In a previous meta-analysis, it was demonstrated that the resting heart rate (RHR) is a potential risk factor for atrial fibrillation (AF). However, the results of that meta-analysis were conflicting, and the relationship between the RHR and AF is still not well established. In the current meta-analysis, our aim is to update evidence with a better statistical model. We searched the Cochrane Library, PubMed, and Embase databases for relevant studies and used a "one-stage approach" with a restricted cubic spline model to summarize the dose-specific relationships between the RHR and AF. Relative risk (RR) was used to measure the effects. In total, 10 studies were included, with a total of 18,630 cases of AF among 431,432 participants. In the dose-response analysis, there was evidence of a nonlinear association between the RHR and the risk of AF (nonlinearity, P < 0.0001), which exhibited a significant J-shaped association between the two factors. An RHR between 68 and 80 bpm had the lowest risk of AF. Among people who had RHR < 70 bpm, the summary RR was 1.09 per 10-RHR decrease (95% confidence interval [CI] = 1.06-1.12; P < 0.001). The results were similar for participants with RHR > 70 bpm (per 10 bpm increase) (RR = 1.06, 95% CI = 1.03-1.08; P < 0.001). Our dose-response meta-analysis revealed a significant J-shaped association between the RHR and AF. Both low RHR and high RHR were associated with an increased risk of AF compared with a modest RHR of 68-80 bpm.

Multimode Computed-Tomography-Guided Thrombolysis under a Prolonged Time Window in Acute Ischemic Stroke Patients with Atrial Fibrillation

Atrial fibrillation (AF) is an independent risk factor for intracranial hemorrhage in patients receiving recombinant-tissue-type plasminogen activator (rt-PA) thrombolytic therapy. Research showed that patients with acute ischemic stroke (AIS) could benefit from multimode computed-tomography- (CT-) guided intravenous thrombolysis over 4.5 hours. The medical data of patients with AIS in our center were retrospectively reviewed, and the data of the multimode CT-guided thrombolytic therapy or nonthrombolytic therapy within different time windows (3-9 hours) were evaluated. 134 AIS cases were selected successfully and divided into three groups: patients with AF treated by rt-PA (AF rt-PA), patients with AF not treated by rt-PA (AF non-rt-PA), and patients without AF treated by rt-PA (non-AF rt-PA). After correcting for the baseline NIH Stroke Scale (NIHSS), sex, age, and hypertension data, the comparison results showed that the NIHSS improved significantly at hospital discharge for rt-PA-treated patients (n = 47) compared to non-rt-PA-treated patients with AIS (n = 31) with AF (P = 0.0156). The NIHSS evaluation at 90 days of follow-up also improved in rt-PA-treated patients (P = 0.0157). The NIHSS at hospital discharge was higher in AF rt-PA-treated patients compared to non-AF rt-PA-treated patients (P = 0.0167) after correction; the difference was not statistically significant at 90 days of follow-up (P = 0.091). Our research showed that the neural function improved after 3-9 hours of thrombolytic therapy with rt-PA in patients with AIS and AF. If there is no thrombolytic taboo, the patients could benefit from the thrombolytic therapy, although the onset time window has been extended to 9 hours.

Characteristics, Mechanism and Long-Term Ablation Outcome of Atrial Tachycardias After Mitral Valvular Surgery and Concomitant Cox-MAZE IV Procedure

The incidence of atrial tachycardia (AT) after rheumatic mitral valvular (RMV) surgery has been well described. However, there have been few reports on the characteristics, mechanism, and long-term ablation outcome of ATs after RMV surgery and concomitant Cox-MAZE IV procedure.The present study reviewed consecutive patients who underwent AT ablation between May 2008 and July 2013. All patients were refractory to antiarrhythmic drugs (AADs) and had a history of RMV surgery and Cox-MAZE IV procedure. A total of 34 patients underwent AT ablation after RMV surgery and concomitant Cox-MAZE IV procedure, and presented 57 mappable and 2 unmappable ATs. The 57 mappable ATs included 14 focal-ATs and 43 reentry-ATs. Ten of the 14 focal-like ATs were located at the pulmonary vein (PV) antrum and border of a box lesion. Of the 43 reentry-ATs, 16 were marco-reentrant around the mitral annulus (MA) and 16 around the tricuspid annulus. There were 41 atypical ATs (non-cavotricuspid isthmus related) including 16 ATs related to the box lesion and 21 ATs related to other Cox-MAZE IV lesions. The AT were successfully terminated in 33 (97.1%) patients. After mean follow-up of 46.9 ± 15.7 months, 25 (73.5%) patients maintained sinus rhythm without AADs after a single procedure and 28 (82.4%) patients after repeated procedures.The recurrent ATs after RMV surgery and concomitant Cox-MAZE IV were mainly reentry mechanism, and largely related to LA. An incomplete lesion or re-conductive gaps in a prior lesion might be the predominant mechanisms for these ATs. Catheter-based mapping and ablation of these ATs seems to be effective and safe during a long-term follow-up.