Difference in left atrial D-dimer level in patients with atrial fibrillation treated with direct oral anticoagulant

Background

Atrial fibrillation (AF) may cause cerebral and systemic embolism. An increased D-dimer level indicates hyperactivation of secondary fibrinolysis, resulting in predilection for thrombosis. To clarify the differential effects of anticoagulation therapy, we compared the D-dimer levels in peripheral and left atrial (LA) blood of atrial fibrillation patients scheduled for ablation.

Methods

We analyzed 141 patients with non-valvular AF (dabigatran, n = 30; apixaban, n = 47; edoxaban, n = 64; mean age: 68 years, male: 60%). Peripheral venous blood and LA blood was collected before pulmonary vein isolation. We examined the laboratory and echocardiographic parameters.

Results

After adjusting for baseline characteristics, D-dimer level in the LA was significantly higher in patients treated with edoxaban than that in those on apixaban (0.77 ± 0.05 vs. 0.60 ± 0.05 μg/mL, P = 0.047), although there were no significant differences in peripheral D-dimer levels. We classified the D-dimer value of the LA into a normal group (< 0.9) and a high value group (≥ 1.0); the peripheral prothrombin fragment F1 + 2 level (odds ratio [OR] 1.012; 95% confidence interval [CI]: 1.003–1.022; P = 0.008) and left ventricular ejection fraction (LVEF) (OR, 0.947; 95% CI, 0.910–0.986; P = 0.008) were potential predictors of high LA D-dimer levels.

Conclusions

In apixaban-treated patients, the D-dimer level in the left atrium was lower than in edoxaban-treated patients on the day of ablation, suggesting that the anticoagulant effect of apixaban on the left atrium is better than that of edoxaban in patients with AF.

Left atrial spontaneous echo contrast occurring in patients with low CHADS2 or CHA2DS2-VASc scores

Background

Left atrial spontaneous echo contrast (LASEC) is common in patients with atrial fibrillation (AF), although scarce information exists on LASEC occurring in nonvalvular AF patients who have low thromboembolic risk scores. We therefore examined prevalence and determinants of LASEC under low CHADS₂ or CHA₂DS₂-VASc scores in these patients.

Methods

Among 713 patients who underwent transesophageal echocardiography, 349 with a CHADS₂ score < 2 (CHADS₂ group) (93 women, mean age 65 years) and 221 with a CHA₂DS₂-VASc score < 2 (CHA₂DS₂-VASc group) (39 women, mean age 62 years) were separately examined for clinical and echocardiographic findings.

Results

LASEC was found in 77 patients of CHADS₂ group (22%) and in 41 of CHA₂DS₂-VASc group (19%). Multivariate logistic regression analysis, adjusted for several parameters including non-paroxysmal AF, LA enlargement (LA diameter ≥ 50 mm), left ventricular (LV) hypertrophy, and an elevated B-type natriuretic peptide (BNP) (BNP ≥200 pg/mL) revealed that for CHADS₂ group, non-paroxysmal AF (Odds ratio 5.65, 95%CI 3.08–10.5, P < 0.001), BNP elevation (Odds ratio 3.42, 95%CI 1.29–9.06, P = 0.013), and LV hypertrophy (Odds ratio 2.26, 95%CI 1.19–4.28, P = 0.013) were significant independent determinants of LASEC, and that for CHA₂DS₂-VASc group, non-paroxysmal AF (Odds ratio 3.38, 95%CI 1.51–7.54, P = 0.003) and LV hypertrophy (Odds ratio 2.53, 95%CI 1.13–5.70, P = 0.025) were significant independent determinants of LASEC.

Conclusions

LASEC was present in a considerable proportion of patients with nonvalvular AF under low thromboembolic risk scores. Information on AF chronicity, BNP, and LV hypertrophy might help identify patients at risk for thromboembolism, although large-scale studies are necessary to confirm our observations.

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.

Chronic Kidney Disease as a Possible Predictor of Left Atrial Thrombogenic Milieu Among Patients with Nonvalvular Atrial Fibrillation

Patients with chronic kidney disease (CKD) experiencing atrial arrhythmia are hypothesized to have elevated CHADS₂ and CHA₂DS₂-VASc scores, thereby predisposed to left atrial (LA) thrombus formation and subsequent thromboembolism. We examined possible association of LA thrombogenic milieu (TM) with CKD in patients with nonvalvular atrial fibrillation. A total of 581 patients (181 women; mean age, 67 years) who underwent transesophageal echocardiography were examined. Patients were divided into 4 groups based on the estimated glomerular filtration rate (eGFR) (ml/min/1.73 m²): eGFR ≥90 (n = 29), 60≤ eGFR <90 (n = 329), 30≤ eGFR <60 (n = 209), and eGFR <30 (n = 14). TM was defined as the presence of LA thrombus, dense spontaneous echo contrast, or LA appendage velocity ≤25 cm/s. Of 581 patients, 147 (25%) had TM. The prevalence of TM increased with decreasing eGFR (4%, 18%, 36%, and 86% for each group, p <0.001). Similar trends were observed for some of the clinical and echocardiographic variables including CHA₂DS₂-VASc score and LA size. Multivariate logistic regression analysis revealed that every 10 ml/min/1.73 m² decrement in eGFR was a significant independent correlate of TM (odds ratio 0.80, p = 0.005), along with nonparoxysmal atrial fibrillation (AF) (odds ratio 0.45, p = 0.004), higher CHA₂DS₂-VASc score (odds ratio 1.24, p = 0.012), every 5 ml/m² increment in LA volume index (odds ratio 1.57, p <0.001), and every 10% decrement in left ventricular ejection fraction (odds ratio 0.51, p <0.001). In conclusion, CKD may be a significant risk factor for LA thrombus formation in patients with nonvalvular atrial fibrillation.

CHA2DS2-VASc Score: A Predictor of Thromboembolic Events and Mortality in Patients With an Implantable Monitoring Device Without Atrial Fibrillation

OBJECTIVE

To determine if the CHA₂DS₂-VASc score (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, stroke or transient ischemic attack, vascular disease, age 65-74 years, sex category) predicts thromboembolism and death in patients without atrial fibrillation in a population with implantable cardiac monitoring devices.

PATIENTS AND METHODS

A retrospective review utilizing the Rochester Epidemiology Project research infrastructure was conducted to evaluate the CHA₂DS₂-VASc tool as a predictor of mortality and ischemic stroke, transient ischemic attack, or systemic embolism in patients without atrial fibrillation. An implantable device was required in the inclusion criteria to discern the absence of atrial fibrillation. The study period was January 1, 2004, through March 7, 2016.

RESULTS

The study population (N=1606) had a mean (SD) age of 69.8 (12.6) years and median follow-up of 4.8 years (range, 0-12 years; quartile 1, 2.6 years and quartile 3, 8.1 years). The number of thromboembolic and mortality events stratified by CHA₂DS₂-VASc score groupings of 0 to 2 (399 patients), 3 to 5 (756 patients), and 6 to 9 (451 patients) were 12 (3.0%), 109 (14.4%), and 123 (27.3%) and 22 (5.5%), 205 (27.1%), and 214 (47.4%), respectively. The CHA₂DS₂-VASc score predicted thromboembolism and death. The hazard ratios (HRs) for thromboembolic events for CHA₂DS₂-VASc scores 3 to 5 and 6 to 9 were 4.84 (95% CI, 2.66-8.80) and 10.53 (95% CI, 5.77-19.21) (reference group, scores 0-2). The HRs for death for the corresponding score categories were 4.45 (95% CI, 2.86-6.91) and 8.18 (95% CI, 5.23-12.78). The CHA₂DS₂-VASc score also predicted development of atrial fibrillation, for which the HRs for scores 3 to 5 and 6 to 9 were 1.51 (95% CI, 1.13-2.00) and 2.17 (95% CI, 1.60-2.95).

CONCLUSION

The CHA₂DS₂-VASc tool predicts thromboembolic events and overall mortality in patients without atrial fibrillation who have implantable devices.

Decreased left ventricular stroke volume is associated with low-grade exercise tolerance in patients with chronic obstructive pulmonary disease

BACKGROUND

Low-grade exercise tolerance is associated with a poor prognosis in patients with chronic obstructive pulmonary disease (COPD). The 6 min walk test (6MWT) is commonly used to evaluate exercise tolerance in patients with COPD. However, little is known regarding the relationship between cardiac function and exercise tolerance in patients with COPD. The aim of this study was to identify predictive factors in cardiac function for low-grade exercise tolerance in patients with stable COPD.

METHODS

We recruited 57 patients with stable COPD (men 54, women 3) to perform the 6MWT. Patients with underlying orthopaedic disease or heart failure were excluded. Cardiac function was evaluated by echocardiography and contrast-enhanced cardiac CT. We also measured pulmonary function and the 6MWT distance.

RESULTS

Forced expiratory volume in 1 s (FEV₁) and per cent predicted FEV, along with left ventricular end diastolic volume and left ventricular cardiac output as measured by cardiac CT, were significantly related to the 6MWT distance. On multivariate analysis, left ventricular stroke volume was the factor most closely associated with a decreased walked distance in the 6MWT.

CONCLUSIONS

Decreased left ventricular stroke volume was associated with low-grade exercise tolerance in patients with stable COPD without heart failure.

Fibrotic atrial cardiomyopathy, atrial fibrillation, and thromboembolism: mechanistic links and clinical inferences

The association of atrial fibrillation (AF) with ischemic stroke has long been recognized; yet, the pathogenic mechanisms underlying this relationship are incompletely understood. Clinical schemas, such as the CHA2DS2-VASc (congestive heart failure, hypertension, age ≥ 75 years, diabetes mellitus, stroke/transient ischemic attack, vascular disease, age 65 to 74 years, sex category) score, incompletely account for thromboembolic risk, and emerging evidence suggests that stroke can occur in patients with AF even after sinus rhythm is restored. Atrial fibrosis correlates with both the persistence and burden of AF, and gadolinium-enhanced magnetic resonance imaging is gaining utility for detection and quantification of the fibrotic substrate, but methodological challenges limit its use. Factors related to evolution of the thrombogenic fibrotic atrial cardiomyopathy support the view that AF is a marker of stroke risk regardless of whether or not the arrhythmia is sustained. Antithrombotic therapy should be guided by a comprehensive assessment of intrinsic risk rather than the presence or absence of AF at a given time.