Mitral regurgitation associated with reduced thromboembolic events in high-risk patients with nonrheumatic atrial fibrillation. Stroke Prevention in Atrial Fibrillation Investigators

Mechanisms and Prediction of Ischemic Stroke in Atrial Fibrillation Patients

Atrial fibrillation (AF) is the most common arrhythmia in adults worldwide and represents an important burden for patients, physicians, and healthcare systems. AF is associated with substantial mortality and morbidity, due to the disease itself and its specific complications, such as the increased risk of stroke and thromboembolic events associated with AF. The temporal relation between AF episodes and stroke is nonetheless incompletely understood. The factors associated with an increased thromboembolic risk remain unclear, as well as the stroke risk stratification. Therefore, in this review, we intend to expose the mechanisms and physiopathology leading to intracardiac thrombus formation and stroke in AF patients, together with the evidence supporting the causal hypothesis. We also expose the risk factors associated with increased risk of stroke, the current different risk stratification tools as well as future prospects for improving this risk stratification.

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.

Prognostic implications of valvular heart disease in patients with non-valvular atrial fibrillation

Background

Valvular heart disease (VHD) in non-valvular atrial fibrillation (AF) is a puzzling clinical entity. The aim of this study was to evaluate the prognostic effect of significant VHD (sVHD) among patients with non-valvular AF.

Methods

This is a post-hoc analysis of the MISOAC-AF trial (NCT02941978). Consecutive inpatients with non-valvular AF who underwent echocardiography were included. sVHD was defined as the presence of at least moderate aortic stenosis (AS) or aortic/mitral/tricuspid regurgitation (AR/MR/TR). Cox regression analyses with covariate adjustments were used for outcome prediction.

Results

In total, 983 patients with non-valvular AF (median age 76 [14] years) were analyzed over a median follow-up period of 32 [20] months. sVHD was diagnosed in 575 (58.5%) AF patients. sVHD was associated with all-cause mortality (21.6%/yr vs. 6.5%/yr; adjusted HR [aHR] 1.55, 95% confidence interval [CI] 1.17–2.06; p = 0.02), cardiovascular mortality (16%/yr vs. 4%/yr; aHR 1.70, 95% CI 1.09–2.66; p = 0.02) and heart failure-hospitalization (5.8%/yr vs. 1.8%/yr; aHR 2.53, 95% CI 1.35–4.63; p = 0.02). The prognostic effect of sVHD was particularly evident in patients aged < 80 years and in those without history of heart failure (p for interaction < 0.05, in both subgroups). After multivariable adjustment, moderate/severe AS and TR were associated with mortality, while AS and MR with heart failure-hospitalization.

Conclusion

Among patients with non-valvular AF, sVHD was highly prevalent and beared high prognostic value across a wide spectrum of clinical outcomes, especially in patients aged < 80 years or in the absence of heart failure. Predominantly AS, as well as MR and TR, were associated with worse prognosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02264-3.

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.

Risk of left atrial appendage thrombus and stroke in patients with atrial fibrillation and mitral regurgitation

OBJECTIVE

To investigate the association of mitral regurgitation (MR) on thromboembolic risk of patients with non-valvular atrial fibrillation (NVAF) undergoing transoesophageal echocardiography (TEE)-guided cardioversion.

METHODS

Data for consecutive patients who underwent TEE-guided cardioversion for NVAF between 2000 and 2012 were analysed. MR severity was assessed by Doppler echocardiography and classified as ≤mild, moderate or severe. Left atrial appendage emptying velocities were averaged for five consecutive cycles. Multivariable regression models were used to identify independent predictors of left atrial appendage thrombus (LAAT) and stroke.

RESULTS

2950 patients (age, 69.3±12.2 years, 67% men) were analysed. 2173 (73.7%) had ≤mild MR; 631 (21.4%), moderate MR; and 146 (4.9%), severe MR. Patients with moderate (age, 72.4±10.7 years) and severe (age, 72.8±12.1 years) MR were older than those with ≤mild MR (age, 68.2±12.5 years). The prevalence of LAAT was 1.5% (n=43). CHA₂DS₂-VASc scores (≤mild MR, 3.0±1.6; moderate MR, 3.5±1.5; severe MR, 3.9±1.5; p<0.001) and heart failure frequency (≤mild MR, 38.4%; moderate MR, 48.0%; severe MR, 69.2%; p<0.001) were increasingly higher with greater MR severity. Multivariable logistic regression analysis showed no association of moderate MR (OR 0.77, 95% CI 0.38 to 1.56) or severe MR (OR 0.55, 95% CI 0.21 to 1.49) with LAAT. During a mean follow-up of 7.3±5.1 years (median 7.5, IQR, 2.7-10.9), 216 patients had an ischaemic stroke. Adjusted Cox regression analysis showed no significant association of moderate MR (HR 1.22, 95% CI 0.88 to 1.68) or severe MR (HR 0.73, 95% CI 0.31 to 1.46) with stroke.

CONCLUSIONS

Among patients with NVAF, the presence or severity of MR was not associated with a decreased risk of LAAT or stroke.

Oral anticoagulant use in patients with atrial fibrillation and mitral valve repair

BACKGROUND

Patients with atrial fibrillation (AF) who have undergone mitral valve repair are at risk for thromboembolic strokes. Prior to 2019, only vitamin K antagonists were recommended for patients with AF who had undergone mitral valve repair despite the introduction of direct oral anticoagulants (DOAC) in 2010.

OBJECTIVE

To characterize the use of anticoagulants in patients with AF who underwent surgical mitral valve repair (sMVR) or transcatheter mitral valve repair (tMVR).

METHODS

We performed a retrospective cohort analysis of patients with AF undergoing sMVR or tMVR between 04/2014 and 12/2018 using Optum's de-identified Clinformatics® Data Mart Database. We identified anticoagulants prescribed within 90 days of discharge from hospitalization.

RESULTS

Overall, 1997 patients with AF underwent valve repair: 1560 underwent sMVR, and 437 underwent tMVR. The mean CHA₂DS₂-VASc score among all patients was 4.1 (SD 1.9). The overall use of anticoagulation was unchanged between 2014 (72.2%) and 2018 (70.0%) (P = .49). Among patients who underwent sMVR or tMVR between April 2014 and December 2018, the use of VKA therapy decreased from 62.9% to 32.1% (P < .01 for trend) and the use of DOACs increased from 12.4% to 37.3% (P < .01 for trend).

CONCLUSIONS

Among patients with AF who underwent sMVR or tMVR between 2014 and 2018, roughly 30% of patients were not treated with any anticoagulant within 90 days of discharge, despite an elevated stroke risk in the cohort. The rate of DOAC use increased steadily over the study period but did not significantly increase the rate of overall anticoagulant use in this high-risk cohort.

Native valve disease in patients with non-valvular atrial fibrillation on warfarin or rivaroxaban

OBJECTIVE

To compare the characteristics and outcomes of patients with atrial fibrillation (AF) and aortic stenosis (AS) with patients with AF with mitral regurgitation (MR) or aortic regurgitation (AR) and patients without significant valve disease (no SVD).

METHODS

Using Rivaroxaban Once-Daily, Oral, Direct Factor Xa Inhibition Compared With Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF) data, we analysed efficacy and safety outcomes, adjusting hazard ratios (HRs) for potential confounders using Cox regression analysis.

RESULTS

Among 14 119 intention-to-treat ROCKET AF trial patients, a trial that excluded patients with mitral stenosis or artificial valve prosthesis, 214 had AS with or without other valve abnormalities, 1726 had MR or AR and 12 179 had no SVD. After adjusting for prognostic factors, the composite of stroke, systemic embolism or vascular death increased approximately twofold in patients with AS (AS 10.84, MR or AR 4.54 and no SVD 4.31 events per 100 patient-years, p=0.0001). All-cause death also significantly increased (AS 11.22, MR or AR 4.90 and no SVD 4.39 events per 100 patient-years, p=0.0003). Major bleeding occurred more frequently in AS (adjusted HR 1.61, confidence intervals (CI) 1.03 to 2.49, p<0.05) and MR or AR (HR 1.30, 1.07 to 1.57, p<0.01) than in no SVD, but there was no difference between AS and MR or AR (HR 1.24, 0.78 to 1.97). The relative efficacy of rivaroxaban versus warfarin was consistent among patients with and without valvular disease. Rivaroxaban was associated with higher rates of major bleeding than warfarin in patients with MR or AR (HR 1.63, 1.15 to 2.31).

CONCLUSIONS

We found that patients with AF and AS on oral anticoagulants may have distinctly different efficacy and safety outcomes than patients with MR or AR or no SVD.

TRIAL REGISTRATION NUMBER

NCT00403767; Post-results.

Thromboembolism in patients with atrial fibrillation with and without left atrial thrombus documented by transesophageal echocardiography

The incidence of cerebrovascular events (CVEs) was investigated in 95 consecutive patients with atrial fibrillation (AF) with left atrial thrombus (LAT) diagnosed by transesophageal echocardiography (TEE) and in 131 age- and sex-matched AF patients without LAT. Compared with patients without LAT, patients with LAT had a larger left atrial diameter (49 versus 44 mm, P < 0.0001), a lower left ventricular ejection fraction (40% versus 50%, P < 0.0001), a higher prevalence of spontaneous echocardiographic contrast (88% versus 25%, P < 0.001), a reduced left atrial appendage emptying velocity (0.25 versus 0.41 cm/s, P < 0.0001), and less use of antiarrhythmic drugs (61% versus 76%, P = 0.03). Before TEE, the prevalence of prior CVE was higher in LAT patients (20%) compared with patients without LAT (8%) (P = 0.01). Fifty-four of 95 LAT patients (57%) and 81 of 131 non-LAT patients (62%) were on warfarin before TEE. The incidence of prior CVE in LAT patients without warfarin (32%) was higher than that in non-LAT patients without warfarin (10%) (P = 0.02). The mortality rate in LAT patients with an international normalized ratio (INR) >or= 2.0 (42%) was higher than that in patients without LAT and an INR >or= 2.0 (11%) (P < 0.001). Fifty-one of 95 LAT patients (54%) underwent repeat TEE before cardioversion (48 patients received warfarin therapy). The thrombus resolved in 40 of 51 patients (78%) after the first TEE. There was no significant difference in INR between the patients with persistent and resolved LAT. AF patients with persistent LAT had a higher incidence of CVE (45%) than the patients with resolved LAT (5%) (P = 0.003). We suggest that patients with LAT be treated with warfarin to maintain an INR between 2.5 and 3.5 rather than between 2.0 and 3.0 because they are at a high risk for new thromboembolism.

Left atrial appendage functions in patients with severe rheumatic mitral regurgitation

AIM

The left atrial appendage (LAA) function was evaluated in patients with severe rheumatic mitral regurgitation, having sinus rhythm or atrial fibrillation, by standard and tissue Doppler echocardiographic examinations.

METHODS AND RESULTS

Sixty patients with rheumatic severe mitral regurgitation were enrolled. The patients (14 females and 6 males) having sinus rhythm were selected as group I and 20 patients (15 females and 5 males) with atrial fibrillation formed group II. 20 healthy subjects (15 female and 5 males) served as the control group (group III). In order to determine the LAA functions, LAA peak filling flow velocity (LAAPFV), LAA peak emptying flow velocity (LAAPEV) and percentage of LAA area change (LAAAC %) were measured. In the TDI records of the subjects with sinus rhythm, the first positive wave identical to the LAA late emptying wave (LEW) following the P-wave was accepted as LAA late systolic wave (LSW), and the second negative wave identical to the LAA late filling flow was accepted as late diastolic wave (LDW). In patients with atrial fibrillation, the positive wave was accepted as LAA late systolic wave (LSW), and the second negative wave identical to the LAA late filling flow was accepted as late diastolic wave (LDW). LAA outflow and inflow velocities were lower in the group having atrial fibrillation (P < 0.002, and P < 0.007, respectively). LAAAC% was also reduced in group II (P < 0.0001). The pulsed Doppler LSW and LDW velocities, measured with TDI method were found to be quite reduced in patients with AF (P: 0.002 and P: 0.001, respectively). The study parameters were statistically similar in patients with normal sinus rhythm and controls.

CONCLUSION

In this study, we found that the LAA functions are impaired in patients with severe mitral regurgitation, having AF, whereas preserved in patients with normal sinus rhythm, compared to controls.

Warfarin Therapy Initiated before Is More Beneficial Than after Transesophageal Echocardiography Detected Left Atrial Thrombus

OBJECTIVE

Warfarin anticoagulation significantly reduces the risk of thromboembolism in patients with atrial fibrillation (AF). However, there are many patients with AF who begin anticoagulation only after left atrial thrombus (LAT) is detected by transesophageal echocardiography (TEE). The impact of anticoagulation in these patients has not been clearly described. The purpose of this study was to investigate the incidence of cerebrovascular accident (CVA) among AF patients who began warfarin before LAT was detected by TEE compared to those who began warfarin only after TEE demonstrated LAT and those did not receive warfarin at any point.

METHOD

Of the 90 consecutive AF patients with LAT (male 48, female 42, age 71.5 +/- 10.1 years), 49 began warfarin more than 3 weeks before TEE (Group I); 29 began warfarin after TEE (Group II); and 12 did not receive warfarin at all (Group III).

RESULTS

The incidence of CVA in Group I (14%, 7/49, prior CVA 5, new CVA after TEE 2) was significantly lower than Group II (45%, 13/29, prior CVA 10, new CVA after TEE 3, P = 0.006) and III (42%, 5/12, prior CVA 3, new CVA after TEE 2, P = 0.047). Patients with persistent LAT had significantly higher incidence (64% vs 23%, P = 0.024) of CVA and lower CVA free survival than those with resolved LAT.

CONCLUSION

The incidence of CVA among AF patients, who began warfarin before LAT detection, is significantly lower than those who began warfarin after LAT detection as well as those who did not receive warfarin at all.

The Impact of Spontaneous Echocardiographic Contrast in Patients With Left Atrial Enlargement Undergoing Cardiac Valvular Surgery

OBJECTIVE

The aim of this study was to evaluate the impact of either left atrial or aortic spontaneous echocardiographic contrast (SEC), as identified on intraoperative transesophageal echocardiography, on short-term morbidity and mortality in patients with left atrial enlargement undergoing cardiac valvular surgery.

DESIGN

Retrospective and observational.

SETTING

Single-center, university teaching hospital.

PARTICIPANTS

The authors identified 197 patients (105 males and 92 females; mean age, 68 +/- 14 years) with left atrial enlargement who underwent surgical intervention for valvular heart disease from January 1, 2004 to January 1, 2005.

MAIN RESULTS

Of the total population, 40 patients (20.3%) showed left atrial SEC, and 10 patients (5.1%) showed aortic SEC. On multivariate analysis, increasing left atrial size and the absence of mitral regurgitation were independent predictors for the presence of left atrial SEC. On multivariate analysis, the presence of atrial fibrillation and a dilated descending aorta were predictive of aortic SEC. Although the identification of left atrial SEC was an echocardiographic marker of an increased risk for thromboembolic events postoperatively, this finding did not hold true for the presence of aortic SEC.

CONCLUSIONS

Intraoperative identification of left atrial dilatation or aortic dilatation is predictive of SEC in the left atrium or descending aorta, respectively. The identification of left atrial SEC is an echocardiographic marker of an increased risk for thromboembolic events in this high-risk population.

Massive cardiac thrombosis in a patient with Sheehan's syndrome

Growth hormone deficiency (GHD) is a risk factor for increased cardiovascular disease, and it has been recently demonstrated that abnormalities in coagulation system might contribute to the increased cardiovascular morbidity and mortality. However, there is not enough data related to the major thrombotic events in GH-deficient patients. We describe the case of a 62-year-old woman with Sheehan's syndrome who developed massive cardiac thrombosis. She was hospitalized with acute pulmonary edema. ECG revealed high ventricular responsive atrial fibrillation (AF) and T-wave inversion on precordial leads. The ejection fraction of left ventricle (LVEF) was measured as 60% by transthoracic echocardiography (TTE) and there was 2nd degree mitral regurgitation with concentric hypertrophic LV walls. Transesophagial echocardiography (TEE) established thrombi both at right atrium and left atrial appendix. Before anticoagulant therapy several hemostatic and fibrinolytic markers were measured. Except increased D-dimer concentration (763.14 mug/L (0-325)) we did not observe any pathological finding in these parameters. After 14 days of discharge, the patient was admitted to the intensive care unit with upper gastrointestinal bleeding. The warfarin and salicylate were stopped for two months. At the end of two months, the patient was again hospitalized with congestive heart failure and there was a high ventricular responsive AF on ECG. TEE was performed and three thrombi were demonstrated at right atrium (RA), left atrium (LA) and left ventricle (LV). There was no active bleeding on upper GIS endoscopy and anticoagulant therapy was restarted. In this particular case massive cardiac thrombi involving three chambers (LA, RA, LV) were more extensive than expected in AF. Moreover, there was a 2nd degree mitral regurgitation in the patient, and based on previous studies mitral regurgitation has been associated with less prevalent LA spontaneous echo contrast and fewer thromboembolic events. Therefore we hypothesized that severe GHD in the present case might be the major contributing factor in massive cardiac thrombosis. In summary, based on previous data there is increased risk of thromboembolic events in GHD although the mechanism is unclear yet. Our case is the first case showing massive cardiac thrombosis in a severe GH-deficient patient with Sheehan's syndrome. Therefore, patients with GHD should be screened carefully for thrombus in clinical practice, and further studies need to be done to understand the relation between GHD and coagulation system.

Are transthoracic echocardiographic parameters associated with atrial fibrillation recurrence or stroke? Results from the Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) study

OBJECTIVES

The purpose of this study was to evaluate the associations of transthoracic echocardiographic parameters with recurrent atrial fibrillation (AF) and/or stroke.

BACKGROUND

The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study, an evaluation of elderly patients with AF at risk for stroke, provided an opportunity to evaluate the implications of echocardiographic parameters in patients with AF.

METHODS

Transthoracic echocardiographic measures of mitral regurgitation (MR), left atrial (LA) diameter, and left ventricular (LV) function were evaluated in the AFFIRM rate- and rhythm-control patients who had sinus rhythm resume and had these data available. Risk for recurrent AF or stroke was evaluated with respect to transthoracic echocardiographic measures.

RESULTS

Of 2,474 patients studied, 457 had > or =2(+)/4(+) MR, and 726 had a LA diameter >4.5 cm. The LV ejection fraction was abnormal in 543 patients. The cumulative probabilities of at least one AF recurrence/stroke were 46%/1% after 1 year and 84%/5% by the end of the trial (> 5 years), respectively. Multivariate analysis showed that randomization to the rhythm-control arm (hazard ratio [HR] = 0.64; p < 0.0001) and a qualifying episode of AF being the first known episode (HR = 0.70; p < 0.0001) were associated with decreased risk. Duration of qualifying AF episode >48 h (HR = 1.55; p < 0.0001) and LA diameter (p = 0.008) were associated with an increased risk of recurrent AF. Recurrent AF was more likely with larger LA diameters (HR = 1.21, 1.16, and 1.32 for mild, moderate, and severe enlargement, respectively). No transthoracic echocardiographic measures were associated with risk of stroke.

CONCLUSIONS

In the AFFIRM study, large transthoracic echocardiographic LA diameters were associated with recurrent AF, but no measured echocardiographic parameter was associated with stroke.

Effects of congestive heart failure on plasma von Willebrand factor and soluble P-selectin concentrations in patients with non-valvar atrial fibrillation

OBJECTIVE

To examine further the relations of plasma von Willebrand factor (vWf, an index of endothelial damage and dysfunction) and soluble P-selectin (sP-sel, an index of platelet activation) concentrations to the presence and onset of clinical congestive heart failure (CHF) and the degree of left ventricular (LV) dysfunction in patients taking part in the SPAF (stroke prevention in atrial fibrillation) study.

METHODS

Plasma concentrations of vWf and sP-sel were measured by enzyme linked immunosorbent assay (ELISA) in 1321 participants in the SPAF III study and related to the presence and onset of clinical CHF, as well as echocardiographic findings. Of the 1321 patients with atrial fibrillation (AF), 331 (25%) had a documented history of clinical heart failure, of which 168 cases were related to a new or recurrent episode of acute decompensated heart failure occurring within the preceding three months.

RESULTS

Mean plasma vWf was higher among patients with AF and CHF (154 (29) v 144 (31) IU/dl, p < 0.001), particularly those with acute or recent decompensated symptoms. Patients with severe LV dysfunction on two dimensional echocardiography and low fractional shortening also had significantly higher vWf concentrations than those with no LV dysfunction. CHF patients with clinical features--with (156 (28) IU/dl) and without (152 (31) IU/dl) LV dysfunction--also had higher mean vWf concentrations than patients with asymptomatic LV dysfunction (146 (31) IU/dl, p < 0.001). The presence of mitral regurgitation in CHF was associated with lower vWf concentrations. Plasma sP-sel concentrations were not affected by presence, onset, or severity of heart failure.

CONCLUSIONS

CHF may contribute to hypercoagulability and thrombotic risk in AF through increased endothelial damage and dysfunction. Patients with acute or recent decompensated features have the highest degree of endothelial damage and dysfunction. The presence of CHF clinical features was an important determinant of plasma vWf concentrations.

Anticoagulation during cardioversion in patients with atrial fibrillation: current clinical practice

The role of anticoagulation in the long-term treatment of atrial fibrillation (AF) has been well established in prospective randomized trials. Less certainty exists on the optimal anticoagulation in the setting of AF cardioversion. Current guidelines advocate anticoagulation for 3-4 weeks before and after cardioversion of AF of >48 hours' duration. Alternatively, early cardioversion may be performed after exclusion of left atrial thrombi by transesophageal echocardiography. However, with conventional anticoagulation, the risk of bleeding has to be considered and, thus, anticoagulation is frequently underused in the clinical setting. Moreover, the role of cardioversion has been questioned by recent trials suggesting no benefit of sinus rhythm restoration over rate control in AF. This article aims to summarize the currently available data on anticoagulation in cardioversion of AF in the context of these new studies and points to some new drugs such as low-molecular weight heparins and oral thrombin inhibitors that may lead to safer anticoagulation for prevention of thromboembolic complications of AF in the future.

Tissue Doppler Properties of the Left Atrial Appendage in Patients with Mitral Valve Disease

OBJECTIVE

The purpose of this study was to compare the left atrial appendage (LAA) tissue Doppler imaging (TDI) with the classical LAA function parameters in patients with mitral valve disease.

METHODS

Twenty patients who had pure mitral regurgitation (group 1), 20 patients who had pure rheumatic mitral stenosis (group 2), and 20 healthy patients (group 3) were included in this study. All the cases were sinus rhythm. In order to determine the LAA functions, LAA late filling (LAALF), and late emptying (LAALE) flow velocities and LAA fractional area change (LAAFAC) were measured. LAA tissue Doppler evaluations were obtained from the PW Doppler, which was placed on the LAA lateral wall in a transverse basal short-axis approach. LAA late systolic (LAALSW) and late diastolic (LAALDW) wave velocities were obtained from TDI records transesophageal echocardiography (TEE).

RESULTS

There were no significant differences among groups 1, 2, and 3 in terms of age, left ventricular (LV) ejection fraction, gender, and heart rate. No differences were observed between group 1 and the control group with respect to LAALE, LAALF, and LAAFAC. LAALE velocity and LAAFAC were significantly decreased in group 2 than group 1. LV diastolic diameter was significantly greater, whereas LAALSW and LAALDW velocities were significantly decreased in group 1 compared with group 3. There were no differences between groups 1 and 2 regarding to LAALSW and LAALDW velocities. LAALE, LAALF, LAALSW, LAALDW velocities, and LAAFAC were significantly decreased in group 2 than group 3.

CONCLUSION

The TDI method may detect the LAA systolic dysfunctions, which cannot be detected using classical methods, on tissue level in patients with mitral regurgitation. In addition, the deterioration of the LAA functions at tissue level in patients with rheumatic mitral stenosis was also detected.

Transesophageal echocardiography before cardioversion of recurrent atrial fibrillation: does absence of previous atrial thrombi preclude the need of a repeat test?

BACKGROUND

Atrial fibrillation (AF) is a recurrent problem that frequently requires repeat cardioversion. Transesophageal echocardiography (TEE) is indicated before cardioversion in patients who are underanticoagulated (warfarin therapy <3 weeks or international normalized ratio [INR] <2.0). It remains uncertain if TEE should be repeated in underanticoagulated patients who had no atrial thrombi detected by previous TEE. Methods and results From January 1996 to June 2001, 76 patients (43 men, 33 women; mean age, 68.8 +/- 10.4 years) who were underanticoagulated and had no atrial thrombi in previous TEE underwent repeat TEE before cardioversion of recurrent AF. The duration of recurrent AF at the time of the second TEE was 5.1 +/- 9.3 months (1 day to 4 years). The underlying diseases included coronary artery disease (n = 30), hypertension (n = 22), valvular heart diseases (n = 8), dilated cardiomyopathy (n = 4), hypertrophic cardiomyopathy (n = 2), and others (n = 10). Eight (10.5%) patients (2 men, 6 women; mean age, 68.6 +/- 6.6 years) were found to have intra-atrial thrombi on the second TEE. Of these 8 patients, 3 had coronary artery disease, 1 had hypertension, 2 had dilated cardiomyopathy, 1 had hypertrophic cardiomyopathy, and 1 had AF of unknown cause. The duration of recurrent AF in patients with and without thrombi was not significantly different (3.6 +/- 4.7 versus 5.3 +/- 9.7 months, P =.22). Of the 8 patients with intra-atrial thrombi on the second TEE, 5 had been taking warfarin for 3 to 4 weeks but had subtherapeutic INR and 3 were taking aspirin only. Compared with patients without intra-atrial thrombi, patients with intra-atrial thrombi had lower ejection fraction (32.5% +/- 18.1% versus 49.9% +/- 14.1%, P =.015), slower left atrial appendage empty velocity (0.22 +/- 0.08 versus 0.41 +/- 0.17 m/s, P <.01), and higher prevalence of spontaneous echo contrast (87.5%) than in patients without intra-atrial thrombi (19.1%, P <.05) but similar left atrial size (49.5 +/- 5.3 versus 47.3 +/- 7.1 mm, P =.15). Cardioversion was cancelled in all patients with atrial thrombi.

CONCLUSIONS

In underanticoagulated patients, repeat TEE is necessary before cardioversion of recurrent AF even if the previous TEE showed no atrial thrombi.

Cerebral ischemic events after diagnosis of mitral valve prolapse: a community-based study of incidence and predictive factors

BACKGROUND AND PURPOSE

Association of mitral valve prolapse (MVP) with ischemic neurological events (INEs) is uncertain.

METHODS

In the community of Olmsted County (Minn), we identified all MVP diagnosed (1989 to 1998) in patients in sinus rhythm with no prior history of INE. We measured INE rates and compared them with expected rates in our community to define the excess risk of INE.

RESULTS

Among 777 eligible subjects (age, 49+/-20 years; 66% female; follow-up, 5.5+/-3.0 years), 30 patients had at least 1 INE during follow-up (at 10 years, 7+/-1%). Compared with expected INEs in the same community, subjects with MVP showed excess risk of lifetime INE (relative risk [RR], 2.2; 95% CI, 1.5 to 3.2; P<0.001) and during follow-up under purely medical management (RR, 1.8; 95% CI, 1.1 to 2.8; P=0.009). Independent determinants of INE were older age (RR, 1.08 per year; 95% CI, 1.04 to 1.11; P<0.001), mitral thickening (RR, 3.2; 95% CI, 1.4 to 7.4; P=0.008), atrial fibrillation (AFib) during follow-up (RR, 4.3; 95% CI, 1.9 to 10.0; P<0.001), and need for cardiac surgery (RR, 2.5; 95% CI, 1.1 to 5.8; P=0.03). INE 10-year rates were low in patients <50 years of age (0.4+/-0.4%, P=0.60 versus expected) but were excessive in patients >50 years of age (16+/-3%, P<0.001 versus expected) or with thickened leaflets (7+/-2%, P<0.001 versus expected). Predictors of follow-up AFib were age, mitral regurgitation, and left atrium diameter (all P<0.01).

CONCLUSIONS

In the community, subjects with MVP display a lifetime excess rate of INE compared with expected. Clinical (older age) and echocardiographic (leaflets thickening) characteristics define patients with MVP at high risk for INE, and subsequent AFib or need for cardiac surgery, both related to the degree of mitral regurgitation, increase the risk of INE.

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.

Atrial fibrillation complicating the course of degenerative mitral regurgitation: determinants and long-term outcome

OBJECTIVES

The study was done to define the incidence, determinants and prognostic implications of onset of atrial fibrillation (AF) during follow-up of mitral regurgitation (MR) initially in sinus rhythm.

BACKGROUND

The rates and clinical implications of AF in MR are undefined.

METHODS

We analyzed the occurrence of AF under conservative management in two populations of patients with degenerative MR in sinus rhythm at diagnosis: 1) 360 patients (65 +/- 13 years, 74% men) with MR due to flail leaflets; and 2) 89 residents of Olmsted County, Minnesota (67 +/- 17 years, 56% men) with grade 3 or 4 MR due to simple mitral valve prolapse (MVP) diagnosed echocardiographically.

RESULTS

In patients with MR due to flail leaflets, AF rates at 5 and 10 years were 18 +/- 3% and 48 +/- 6%, respectively, and the linearized rate was 5.0 +/- 0.7% per year. Development of AF during follow-up was independently associated with high risk of cardiac death or heart failure (adjusted risk ratio 2.23, p = 0.025). The AF rate at 10 years was higher in patients >or=65 years (75 +/- 10% vs. 24 +/- 6%, p < 0.0001) and in those with baseline left atrial (LA) dimension >or=50 mm (67 +/- 8% vs. 37 +/- 9%, p < 0.001). In multivariate analysis, independent baseline predictors of AF were age and LA diameter (both p < 0.01). In patients with MR due to MVP, similar rates of AF (41 +/- 7% vs. 44 +/- 6% at nine years, p > 0.50) and predictors of AF (age and LA dimension, both p < 0.006) were noted.

CONCLUSIONS

In patients with degenerative MR in sinus rhythm at diagnosis, the incidence of AF occurring under conservative management is high and similar whether the cause of MR is flail leaflet or simple MVP. After onset of AF, an increased cardiac mortality and morbidity are both observed under conservative management. The risk of AF increases with advancing age and larger LA dimension. These data suggest that the clinical management of MR should take into account the high incidence, excess risk, and predictors of AF.

Anti-thrombotic strategies for patients with atrial fibrillation and heart failure

Atrial fibrillation occurs commonly in the setting of congestive heart failure and, in fact can cause left ventricular dysfunction due to a rapid ventricular response over time, termed tachycardia-mediated cardiomyopathy. The combination of atrial fibrillation and congestive heart failure leads to a high risk of stroke for the patient and appropriate antithrombotic therapy can minimize this incidence of stroke. Stroke risk can be markedly reduced by treatment with warfarin and complications of anticoagulation minimized by close attention to maintaining the INR between 2.0 and 3.0.

Aortic spontaneous echocardiographic contrast and hemostatic markers in patients with nonrheumatic atrial fibrillation

OBJECTIVES

To determine the relationship between spontaneous echocardiographic contrast (SEC) in the descending thoracic aorta and plasma levels of hemostatic markers in patients with nonrheumatic atrial fibrillation (AF).

DESIGN AND SETTINGS

A cross-sectional study at a university hospital.

PATIENTS AND MEASUREMENTS

In 91 consecutive patients (mean +/- SE age, 70 +/- 1 years; 68 men) with nonrheumatic AF who underwent transesophageal echocardiography, plasma levels of markers for platelet activity (platelet factor 4 [PF4] and beta-thromboglobulin [beta-TG]), thrombotic status (thrombin-antithrombin III complex [TAT]), and fibrinolytic status (D-dimer and plasmin-alpha(2)-plasmin inhibitor complex [PIC]) were determined.

RESULTS

Forty-three patients who had aortic SEC (AoSEC) were older (72 years vs 68 years; p < 0.05) and had a higher prevalence of chronic AF (88% vs 52%; p < 0.05) than 48 patients without AoSEC. TAT, PIC, and D-dimer levels were significantly higher in patients with AoSEC than in those without AoSEC, whereas PF4 and beta-TG levels were not different between the two groups. Although the prevalence of cerebral embolism did not differ between the two groups (23% vs 29%), the prevalence of peripheral embolism was higher in patients with AoSEC than in those without AoSEC (10% vs 0%; p < 0.05). Multivariate analysis revealed mitral regurgitation (odds ratio, 7.53; p < 0.02), SEC in the left atrium (odds ratio, 2.14; p < 0.02), and aortic atherosclerosis (odds ratio, 1.87; p < 0.04) emerged as independent predictors of AoSEC.

CONCLUSIONS

Patients with nonrheumatic AF who have AoSEC appear to have enhanced coagulation activity but not platelet activity. Intensive anticoagulation treatment might be required for these patients.

Assessment of left atrial appendage filling pattern by using intravenous administration of microbubbles: comparison between mitral stenosis and mitral regurgitation

Mitral stenosis (MS) and mitral regurgitation (MR) are the most frequent conditions that cause a dilation and dysfunction of the left atrial appendage (LAA). Despite similarly dilated LAA in patients with MS and MR, the incidence of LAA thrombi and the risk of thromboembolism is different between these patients. The purpose of this study was to characterize the filling pattern of LAA by using intravenous administration of perfluorocarbon-exposed dextrose albumin (PESDA) during transesophageal echocardiographic examination in patients with MS and MR. Twenty-four patients with moderate to severe MS, 12 patients with severe MR, and a control group including 30 patients with conditions other than mitral valve disease underwent transesophageal echocardiographic examination with an intravenous bolus injection of PESDA. LAA emptying and filling velocities and maximal and minimal areas of LAA and LAA ejection fraction were measured. Digital gray-scale intensity (GSI) of the left atrial (LA) and LAA cavity after PESDA injection was measured by off-line analysis. Compared with control patients, patients with MS or MR had larger maximal and minimal areas of LAA and reduced LAA ejection fraction. LAA peak emptying flow velocity was significantly lower in patients with MS compared with those of MR or control patients. LAA peak filling velocity was significantly lower in patients with MS compared with that of control patients. However, there was no significant difference of LAA peak filling velocity between the patients with MS and MR. There was no significant difference of GSI ratio of LAA and LA between patients with MR and control patients; however, GSI ratio of LAA and LA was significantly lower in patients with MS compared with that of MR. The incidence of LAA spontaneous echo contrast and LAA thrombi in patients with MS was significantly higher than that of the patients with MR and control subjects (P <.005). Despite similarly dilated LAA area and depressed contractile function of LAA in patients with MS and MR compared with control patients, profoundly impaired LAA filling with resultant flow stasis was demonstrated by contrast echocardiography in patients with MS. These findings may explain the higher incidence of LAA spontaneous echo contrast and thrombus in patients with MS.

Prevention of cerebral thromboembolism by low-dose anticoagulant therapy in atrial fibrillation with mitral regurgitation

Controversy exists regarding the influence of mitral regurgitation (MR) on thromboembolic risk in patients with atrial fibrillation. We aimed to investigate retrospectively a reduction of risk for stroke due to MR in atrial fibrillation and to evaluate the effectiveness of low-intensity anticoagulation therapy. In 313 patients with atrial fibrillation, transthoracic echocardiography was performed and MR was graded. Between the groups with no or mild MR (n = 209) and with moderate or severe MR (n = 104), age, sex, treatment, history of diabetes, hypertension, hyperlipemia and mitral stenosis, and previous stroke were compared. No significant differences in clinical characteristics, treatment, or history were observed between the two groups. The incidence of thromboembolism was significantly higher in the group with no MR (48 patients [23%]) than in the group with MR (14 patients [13%], p < 0.05). In the MR group, previous stroke was frequently observed in patients without warfarin treatment (11 of 51 patients) compared with patients with low-dose warfarin treatment (international normalized ratio of 1.6-1.8) (3 of 53 patients, p < 0.05). Consequently, the thromboembolic event was markedly prevented by low-dose warfarin treatment.

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

Integrated backscatter (IB) provides the quantitative assessment of left atrial spontaneous echo contrast (SEC). The IB intensity of the left atrial cavity relative to the left ventricular cavity is related to atrial thrombus in patients with atrial fibrillation (AF) or sinus rhythm. However, little is known about the relation between the quantitative SEC value of the left atrial cavity and variables implying thromboembolism in nonvalvular AF. To examine this relation, we performed transesophageal echo-cardiography with IB analysis in 65 patients with chronic nonvalvular AF. The quantitative SEC value of the left atrial cavity was defined as the difference between atrial IB intensity and ventricular IB intensity (corrected IB intensity). The corrected IB intensity was correlated with the left atrial dimension (r = 0.25, P =.049), the left atrial appendage velocity (r = -0.41, P <.001), and the duration of AF (r = 0.23, P =. 023). The corrected IB intensity was higher in patients who had a history of hypertension (3.2 +/- 2.2 dB versus 2.0 +/- 1.6 dB, P =. 018), SEC (3.9 +/- 1.9 dB versus 1.4 +/- 1.1 dB, P =.002), and left atrial thrombus (4.5 +/- 2.7 dB versus 2.2 +/- 1.7 dB, P <.001) when compared with those who did not have these abnormalities. The corrected IB intensity was significantly lower in patients with significant mitral regurgitation than in those without it (1.1 +/- 1. 2 dB versus 2.7 +/- 2.0 dB, P =.036). When the cutoff value of the corrected IB intensity was set at >/=2.0 dB, the sensitivity for left atrial thrombus was 78% and the specificity was 55%. In patients with chronic nonvalvular AF, the quantitative SEC value of the left atrial cavity depends on the duration of AF as well as the left atrial dimension and appendage velocity. Although IB may be capable of identifying patients with higher risk of cardiogenic embolism, a large-scale prospective study is needed to actually establish this.

Transesophageal echocardiography risk factors for stroke in nonvalvular atrial fibrillation

Atrial fibrillation is a common arrhythmia, particularly in the older age groups. It confers an increased risk of thromboembolism to these patients, and multiple clinical risk factors have been identified to be useful in predicting the risks of thromboembolic events. Recent studies have evaluated the role of transesophageal echocardiography (TEE) in the evaluation of patients with atrial fibrillation. The purpose of this review is to evaluate the significance of transesophageal echocardiographic findings in the prediction of thromboembolic events, particularly stroke, in patients with nonvalvular atrial fibrillation, with an emphasis on recently reported prospective studies. Aortic plaque and left atrial appendage abnormalities are identified as independent predictors of thromboembolic events. Although they are associated with clinical events, they also have independent incremental prognostic values. Other transesophageal echocardiographic findings, such as patent foramen ovale and atrial septal aneurysm, have not been found to be predictors of thromboembolic events in this patient group. Thus, TEE is a useful tool in stratifying patients with nonvalvular atrial fibrillation into different risk groups in terms of thromboembolic events, and it will likely play an important role in future studies to assess new treatment strategies in high-risk patients with atrial fibrillation.

Mild mitral regurgitation was associated with increased prevalence of thromboembolic events in patients with nonrheumatic atrial fibrillation

Although several studies demonstrated that the presence of significant mitral regurgitation was associated with reduced occurrence of thromboembolism, little data is available concerning the effect of mild mitral regurgitation on the occurrence of thromboembolic events. To evaluate the association between mild mitral regurgitation and thromboembolic events, we reviewed 232 patients' records between January 1996 and September 1997 who had nonrheumatic atrial fibrillation. There were 59 patients (25%) with mitral regurgitation > or = grade 2, 69 patients (30%) with grade 1 mitral regurgitation, and 104 patients (45%) with no mitral regurgitation. Patients with grade 1 mitral regurgitation had significantly higher prevalence of thromboembolic events (28%) than those with mitral regurgitation > or = grade 2 (8%, P=0.006) or those with no mitral regurgitation (11%, P=0.007). A history of previous thromboembolic events were compared between 173 patients with grade 1 mitral regurgitation and those with no mitral regurgitation using the logistic regression analysis adjusted for age, sex, administration of warfarin, and presence of hypertension, diabetes mellitus, structural heart disease, enlarged left atrium (> or = 40 mm), chronic atrial fibrillation, and grade 1 mitral regurgitation. Grade 1 mitral regurgitation (odds ratio=2.689, 95% confidence interval=1.039-7.189, P=0.0434) and no warfarin administration (odds ratio=0.045, 95% confidence interval=0.002-0.242, P=0.0036) were significantly associated with the history of thromboembolic events. The presence of mild mitral regurgitation in nonrheumatic atrial fibrillation was associated with higher prevalence of thromboembolic events.

Stroke prevention in atrial fibrillation

Nonvalvular atrial fibrillation (AF) is an independent risk factor for stroke. The overall risk of ischemic stroke in patients experiencing AF without prior stroke averages about 5% per year, but varies depending on the presence of coexistent thromboembolic risk factors. Patients with AF with low (about 1% per year), moderate (2%-4% per year) and high (> or = 6% per year) stroke risks have been identified, but the generalizability of available risk stratification schemes to clinical practice has not been defined. Adjusted-dose warfarin (target International Normalized Ratio 2-3) is highly efficacious for prevention of stroke in patients with AF (about 60% reduction) and is relatively safe for selected patients, if carefully monitored. Aspirin has a modest effect on reducing stroke (about 20% reduction). The role of transesophageal echocardiography is routine management of AF remains unsettled. Warfarin therapy should be considered for patients with AF predicted to have a high risk of stroke and who can safely receive it. Aspirin may be indicated for patients with AF at low risk for stroke and for those who cannot safely receive adjusted-dose warfarin. For those with moderate stroke risk, individual bleeding risks during anticoagulation and patient preferences should guide antithrombotic therapy.

Pathophysiologic correlates of thromboembolism in nonvalvular atrial fibrillation: II. Dense spontaneous echocardiographic contrast (The Stroke Prevention in Atrial Fibrillation [SPAF-III] study)

We analyzed transesophageal echocardiograms from 772 participants in the Stroke Prevention in Atrial Fibrillation (SPAF-III) study, characterizing spontaneous echocardiographic contrast (SEC) in the left atrium or appendage as faint or dense. The association of dense SEC with stroke risk factors and anatomic, hemodynamic, and hemostatic parameters related to specific thromboembolic mechanisms was evaluated by multivariate analysis. Spontaneous echocardiographic contrast was present in 55% of patients and was dense in 13%. Age (odds ratio [OR] 2.4/decade, P <.001), constant atrial fibrillation (OR 6.9, P <.001), history of hypertension (OR 3. 2, P <.001), and current tobacco smoking (OR 2.6, P =.04) were independent clinical predictors of dense SEC. Multivariate analysis of clinical, echocardiographic, and hemostatic parameters yielded age as the sole independent clinical predictor of dense SEC (OR 2. 4/decade, P <.001). Other independent predictors were measures of left atrial/appendage flow dynamics, left atrial size (OR 2.4/cm diameter, M-mode, P <.001), atherosclerotic aortic plaque (OR 2.8, P =.002), and plasma fibrinogen >350 mg/dL (P <.001). Results were similar when SEC of any density was analyzed. In conclusion, SEC occurred in more than half of these patients with prospectively defined nonvalvular atrial fibrillation but was usually faint. Dense SEC was strongly associated with previously reported clinical predictors of stroke, linking them to thromboembolism through atrial stasis. Diverse pathophysiologic factors including atrial stasis, fibrinogen level, and aortic plaque influence SEC.

Echocardiographic assessment of the left atrial appendage

The left atrial (LA) appendage is a common source of cardiac thrombus formation associated with systemic embolism. Transesophageal echocardiography allows a detailed evaluation of the structure and function of the appendage by two-dimensional imaging and Doppler interrogation of appendage flow. Specific flow patterns, reflecting appendage function, have been characterized for normal sinus rhythm and various abnormal cardiac rhythms. Appendage dysfunction has been associated with LA appendage spontaneous echocardiographic contrast, thrombus formation and thromboembolism. These associations have been studied extensively in patients with atrial fibrillation or atrial flutter, in patients undergoing cardioversion of atrial arrhythmias and in patients with mitral valve disease. The present review summarizes the literature on the echocardiographic assessment of LA appendage structure, function and dysfunction, which has become an integral part of the routine clinical transesophageal echocardiographic examination.

Atrial fibrillation and thromboembolism: a decade of progress in stroke prevention

Atrial fibrillation is associated with a sixfold increased risk for stroke. More than a dozen published randomized trials of anticoagulants or antiplatelet agents for stroke prevention provide solid evidence on which to base antithrombotic prophylaxis. Adjusted-dose warfarin reduces risk for stroke by about 60% compared with placebo, aspirin reduces this risk (primarily for nondisabling stroke) by about 20% compared with placebo, and warfarin reduces it by about 40% compared with aspirin. Warfarin provides maximal protection against stroke at international normalized ratios of 2.0 to 3.0. Risk stratification of patients with atrial fibrillation identifies those who potentially benefit most or least from anticoagulation; this is important because a substantial percentage of patients with atrial fibrillation have relatively low rates of stroke if they are given aspirin. Many elderly patients with recurrent intermittent atrial fibrillation experience high rates of stroke and benefit from anticoagulation. The value of precordial or transesophageal echocardiography in addition to clinical risk stratifiers for stratifying stroke risk is controversial. Altered hemostasis favoring thrombosis may contribute to formation of atrial appendage thrombus, but these conditions remain ill defined. The past decade has brought unprecedented progress toward understanding thromboembolism in patients with atrial fibrillation and has changed the clinical perspective of a prevalent cardiac arrhythmia into an important opportunity for stroke prevention. Making the most of this promise calls for appreciation of the epidemiology of atrial fibrillation and the concept of risk specificity in the face of diverse therapeutic options.

Pharmacotherapy of atrial fibrillation

Atrial fibrillation (AF) remains a widespread health problem and the drugs available for its treatment suffer from several drawbacks, including potentially lethal proarrhythmia, serious non-cardiac toxicity and limited efficacy. The evidence for efficacy of currently available anti-arrhythmic agents for sinus rhythm restoration and maintenance is reviewed, with emphasis on randomised trials when available. The current approach to thromboembolism prophylaxis in AF is summarised.

Factors associated with ischemic stroke during aspirin therapy in atrial fibrillation: analysis of 2012 participants in the SPAF I-III clinical trials. The Stroke Prevention in Atrial Fibrillation (SPAF) Investigators

BACKGROUND AND PURPOSE

Nonvalvular atrial fibrillation (AF) is a strong, independent risk factor for stroke, but the absolute rate of stroke varies widely among AF patients, importantly influencing the potential benefit of antithrombotic prophylaxis. We explore factors associated with ischemic stroke in AF patients taking aspirin.

METHODS

We performed multivariate logistic regression analysis of 2012 participants given aspirin alone or in combination with low, inefficacious doses of warfarin in the Stroke Prevention in Atrial Fibrillation I-III trials followed for a mean of 2.0 years, during which 130 ischemic strokes were observed.

RESULTS

Age (relative risk [RR]=1.8 per decade, P<0.001), female sex (RR=1.6, P=0.01), history of hypertension (RR=2.0, P<0.001), systolic blood pressure >160 mm Hg (RR=2.3, P<0.001), and prior stroke or transient ischemic attack (RR=2.9, P<0.001) were independently associated with increased stroke risk. Regular consumption of >/=14 alcohol-containing drinks per week was associated with reduced stroke risk (adjusted RR=0.4, P=0.04). Among SPAF III participants, estrogen hormone replacement therapy was associated with a higher risk of ischemic stroke (adjusted RR=3.2, P=0.007). With the use of these variables, a risk stratification scheme for primary prevention separated participants into those with high (7.1%/y, 22% of the cohort), moderate (2.6%/y, 37% of the cohort), and low (0.9%/y, 41% of the cohort) rates of stroke. Ischemic strokes in low-risk participants were less often disabling (P<0.001).

CONCLUSIONS

Patients with AF who have high and low rates of stroke during treatment with aspirin can be identified. However, validation of our risk stratification scheme is necessary before it can be applied with confidence to clinical management. Postmenopausal estrogen replacement therapy and moderate alcohol consumption may additionally modify the risk of stroke in AF, but these findings require confirmation.

Left atrial diameter in nonvalvular atrial fibrillation: An echocardiographic study. Stroke Prevention in Atrial Fibrillation Investigators

BACKGROUND

The left atrium (LA) is usually enlarged in patients with nonvalvular atrial fibrillation (AF), but factors associated with LA diameter are incompletely defined.

METHODS AND RESULTS

This transthoracic echocardiographic cohort study includes 3465 participants with nonvalvular AF in 3 multicenter clinical trials. LA diameter determined by M-mode echocardiography was correlated with clinical and echocardiographic features by cross-sectional multivariate regression analyses. The mean LA diameter was 47 +/- 8 mm, on average 6 mm larger in those with AF at the time of echocardiography than in those with sinus rhythm (48 vs 42 mm, P <. 001). Patient age and body weight were independently predictive of LA diameter (P <.0001), but sex, body surface area, and body mass index were not. The estimated independent contribution of atrial rhythm to LA diameter was approximately 2.5 mm. Prolonged duration of AF, left ventricular dilatation and increased muscle mass, mitral regurgitation, annular calcification, and hypertension were additional independent predictors of LA diameter.

CONCLUSIONS

Multiple factors appear to contribute to LA enlargement in patients with nonvalvular AF, including the presence and persistence of the dysrhythmia.

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

In this study we aimed to analyze, with reference to mitral regurgitation (MR), the incidence and predictors of left atrial (LA) thrombus and spontaneous echo contrast in patients with rheumatic valve disease before and after mitral valve replacement. The incidence of LA thrombus is known to be less in patients with MR. The impact of mitral valve replacement on this beneficial effect has not been studied in detail. The study included 169 consecutive patients (59 men and 110 women, average age 40 +/- 13 years) with rheumatic mitral valve disease who underwent transesophageal echocardiographic examination 1 to 3 days before and within 7 days (mean 4.0 +/- 1.3) after mitral valve replacement using mechanical prostheses in a single institution. The preoperative incidence of echocardiographic LA spontaneous echo contrast (SEC) was 1.1%, 30%, and 54%, and the incidence of thrombus was 1.1%, 13%, and 17% in the groups with MR, combined mitral stenosis + MR, and isolated mitral stenosis, respectively. In the MR group, SEC and thrombus incidence increased significantly after surgery. The independent predictors for postoperative thrombus development were atrial fibrillation, postoperative SEC, and preoperative thrombus. Thrombus recurred after surgery in 64% of 14 patients who had surgical thrombectomy. The presence of postoperative MR was associated with decreased risk of postoperative SEC and thrombus development. The interaction between MR and SEC and thrombus both before and after surgery provides further support for the protective effect of MR against LA thrombus formation.

Role of echocardiography in patients undergoing elective cardioversion of atrial fibrillation

Echocardiography has emerged as a fundamental tool in the evaluation of patients with atrial fibrillation (AF). Transthoracic echocardiography remains a primary tool for the evaluation and management of many patients presenting with their first episode of AF, but it is not adequate for exclusion of atrial thrombi. TEE offers excellent visualization of the atria and accurate identification or exclusion of thrombi. In concert with therapeutic anticoagulation, a TEE-guided approach to early cardioversion appears to have a safety profile similar to that of conventional therapy (1 month of precardioversion warfarin). The TEE-guided approach offers the advantages of simplified anticoagulation management and shorter duration of sustained AF, thereby allowing for a more rapid recovery of atrial mechanical function. Warfarin should be continued for 1 month after cardioversion to allow for more complete recovery of atrial function and for prophylaxis should the patient revert to AF. Cost-effectiveness models demonstrate that TEE-guided cardioversion represents a cost-effective strategy, but only if the transthoracic echocardiogram is omitted. For patients with a thrombus on the initial TEE, follow-up TEE (to document thrombus resolution) is recommended before cardioversion.