Atrial fibrillation and stroke: new ideas, persisting dilemmas

Thromboembolic and bleeding events after valvular intervention in patients with atrial fibrillation

AIM

To assess outcomes after cardiac surgery with biological valve replacement, valve repair or transcatheter aortic valve implantation (TAVI) in patients with atrial fibrillation (AF) in accordance with oral anticoagulant (OAC) treatment.

METHODS

All patients in Sweden undergoing valvular intervention with AF were included. Associations between OAC exposure and cardiovascular (CV) events (composite of CV death, ischaemic stroke or systemic embolism) and major bleeding were investigated using Cox regression analysis. The analysis was separated in time periods of 0-3 and 3-12 months after discharge.

RESULTS

4730 patients were included in the first time period, 54.0% had received a surgical biological valve prosthesis, 23.8% valve repair and 22.2% TAVI. Exposure to warfarin (comparator) was 62.3%, to non-vitamin K antagonist oral anticoagulants (NOACs) 10.0% and to no OAC 27.7%. NOAC exposure was associated with similar risk of the composite CV outcome and major bleeding from 0 to 3 months. No OAC was associated with increased risk of the composite CV outcome (HR 1.71; 95% CI 1.26 to 2.32) and similar risk of major bleeding. Further analysis of the bioprosthetic valve replacement subgroup indicated increased risk of CV death when exposed to NOAC (HR 2.58; 95% CI 1.15 to 5.78) and no OAC (HR 2.82; 95% CI 1.65 to 4.82) compared with warfarin from 0 to 3 months. No differences were seen between 3 and 12 months.

CONCLUSION

In this registry-based cohort study of patients with AF with severe valvular heart disease undergoing various valvular interventions, NOAC appears to be comparable with warfarin regarding efficacy and safety. Patients not receiving OAC had higher risk of CV events. NOAC was associated with increased CV death compared with warfarin in the surgical bioprosthetic valve replacement subgroup, illustrating the importance of being cautious when extrapolating data from one patient group to another. Further studies comparing NOAC and warfarin in the early postoperative phase are warranted, especially following surgical bioprosthetic valve replacement.

Novel Oral Anticoagulants in Patients With Atrial Fibrillation and Moderate to Severe Mitral Stenosis: A Systematic Review

The use of novel oral anticoagulants (NOAC) in patients with moderate to severe mitral stenosis (MS) and atrial fibrillation (AF) is not recommended. We aimed to evaluate the efficacy and safety of NOAC usage compared to vitamin K antagonist (VKA) in patients with moderate to severe MS and AF. We conducted a systematic review to identify articles that compared warfarin to NOAC in patients with moderate to severe MS and AF. Only four studies (two observational studies and two trials) met our search criteria and reported a total of 7529 patients with MS and AF with MS and AF, 4138 of them treated with NOAC. In both observational studies, the severity of MS was not determined, and there was heterogeneity in MS etiology. Nevertheless, both studies showed a positive signal toward the efficacy and safety of NOAC compared to VKA in this population. A randomized pilot trial (n=40) was done on patients with moderate to severe MS, and it showed further acceptable efficacy and safety for rivaroxaban use. However, a larger randomized controlled trial (n=4531) disclosed that VKA (warfarin) led to a significantly lower rate of a composite of cardiovascular events or mortality than rivaroxaban, without a higher rate of major bleeding but not fatal bleeding. Our systematic review provides exploratory information on NOAC safety and effectiveness in patients with MS; it also discourages using NOACs for patients with moderate to severe MS and supports the current treatment guidelines. However, more dedicated clinical trials evaluating the use of NOACs in moderate to severe MS are underway. They will categorically establish the safety profile and clinical effectiveness of NOAC in this high-risk population.

Atrial Fibrillation and Ischemic Stroke: A Clinical Review

Atrial fibrillation (AF) is an important risk factor for ischemic stroke resulting in a fivefold increased stroke risk and a twofold increased mortality. Our understanding of stroke mechanisms in AF has evolved since the concept of atrial cardiopathy was introduced as an underlying pathological change, with both AF and thromboembolism being common manifestations and outcomes. Despite the strong association with stroke, there is no evidence that screening for AF in asymptomatic patients improves clinical outcomes; however, there is strong evidence that patients with embolic stroke of undetermined source may require long-term monitoring to detect silent or paroxysmal AF. Stroke prevention in patients at risk, assessed by the CHA₂DS₂-VASc score, was traditionally achieved with warfarin; however, direct oral anticoagulants have solidified their role as safe and effective alternatives. Additionally, left atrial appendage exclusion has emerged as a viable option in patients intolerant of anticoagulation. When patients with AF have an acute stroke, the timing of initiation or resumption of anticoagulation for secondary stroke prevention has to be balanced against the risk of hemorrhagic conversion. Multiple randomized clinical trials are currently underway to determine the best timing for administration of anticoagulants following acute ischemic stroke.

Atrial Fibrillation and Stroke

Atrial fibrillation (AF) is the most common cardiac arrythmia and a major cause of stroke, heart failure, sudden death, and cardiovascular morbidity. AF increases risk of thromboembolic stroke via stasis in the left atrium and subsequent embolization to the brain. In patients with acute ischemic stroke, it is essential that clinicians undertake careful investigation to search for AF. In these patients, up to 23.7% eventually are found to have underlying AF. Oral anticoagulation is effective in prevention of strokes secondary to AF, reducing overall stroke numbers by approximately 64%. Left atrial appendage occlusion is promising for prevention of stroke in AF.

Unconventional combination of left atrial appendage device occlusion in patients with atrial fibrillation who needed concomitant catheter interventions for underlying structural heart disease

Objectives

Left atrial appendage occlusion (LAAO) in non-valvar atrial fibrillation (AF) reduces cardioembolic strokes. Despite increased risk, trials exclude valvar AF in structural heart diseases where clots extend beyond appendage.

Methods

Patients with AF and relative risks for oral anticoagulation (OAC) needing structural interventions underwent concomitant LAAO. After six months of OAC, aspirin was continued. Transesophageal echocardiogram was done three monthly till one year and yearly thereafter. The patient demographics, procedural details, post-procedural follow-up were analyzed.

Results

Nine patients aged 51.5 ± 6.3 years with AF underwent LAAO concomitantly with balloon mitral valvotomy in four patients, atrial septal defect device closure in four and periprosthetic mitral leak closure in one patient. Six patients had heart failure, four had prior embolic events, and two had documented LAA thrombus. The mean CHADS₂VASc score was 2.44 ± 0.8 and mean HASBLED score was 3.0 ± 0.8. Devices included Amplatzer Cardiac Plug™ in six patients, LAmbre™ Lifetech device in two and Watchman™ device in one. All procedures were successful without acute complications. A patient developed pericardial effusion at six months requiring pericardiocentesis. Early device-associated thrombus in one patient resolved after OAC for six months. No embolic events occurred on follow-up.

Conclusion

On a detailed literature search, this largest LAAO experience in structural heart diseases indicates its utility. OAC for six months followed by aspirin seems to prevent thrombus formation in these patients. The only incidence of early thrombus formation indicates immunity from clot formation after device endothelialisation. Larger multicenter trials combining LAAO with structural interventions in valvular AF are warranted in developing nations.

Diagnosis of left atrial appendage thrombus in patients with atrial fibrillation: delayed contrast-enhanced cardiac CT

Objectives

The current reference standard for diagnosing LAA thrombi is transesophageal echocardiography (TEE), a semi-invasive technique. We aimed to devise an optimal protocol for cardiac computed tomography (CCT) in diagnosing left atrial appendage (LAA) thrombus in patients with atrial fibrillation (AF), using TEE as reference standard.

Methods

Two hundred sixty consecutive patients referred for radiofrequency ablation for AF were prospectively enrolled. All patients underwent CCT and TEE within 2 hours. The CCT protocol included one standard angiographic phase and three delayed acquisitions at 1-, 3-, and 6-min after contrast injection. Thrombi were defined as persisting defects at 6-min delayed acquisition.

Results

TEE demonstrated spontaneous contrast in 52 (20%) patients and thrombus in 10 (4%). In 63 patients (24%), CCT demonstrated LAA early filling defects at angiographic phase. Among them, 15 (6%) had a persistent defect at 1-min, 12 (5%) at 3-min, and 10 (4%) at 6-min. All 10 thrombi diagnosed on TEE were correctly identified by delayed CCT, without any false positives. For all phases, sensitivity and negative predictive were 100%. Specificity increased from 79% for the angiographic phase to 100% at 6-min. Positive predictive value increased from 16% to 100%. Estimated radiation exposure was 2.08 ± 0.76 mSv (mean ± standard deviation) for the angiographic phase and 0.45 ± 0.23 mSv for each delayed phase.

Conclusion

A CCT protocol adding a 6-min delayed phase to the angiographic phase can be considered optimized for the diagnosis of LAA thrombi, with a low radiation dose.

Key Points

• In patients with persistent atrial fibrillation referred for ablation procedures, a cardiac CT examination comprising an angiographic-phase acquisition and, in case of filling defects, a 6-min delayed phase may help reduce the need for transesophageal echocardiography.

• Cardiac CT would provide morphological and volumetric data, along with the potential to exclude the presence of thrombi in the left atrial appendage.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Impact of Valvular Heart Disease on Mortality, Thromboembolic and Cardiac Events in Japanese Patients With Atrial Fibrillation - The Fushimi AF Registry

BACKGROUND

There is a growing burden of valvular heart disease (VHD) and atrial fibrillation (AF) due to population aging, but data regarding the characteristics and outcomes of patients with AF and concomitant VHD are lacking.Methods and Results:The Fushimi AF Registry is a community-based prospective survey of AF patients in Fushimi-ku, Kyoto. Among 3,566 patients with available echocardiographic data, 20% had VHD, consisting of 131 valvular AF (VAF: 3.7%) and 583 nonvalvular AF with VHD (NVAF-VHD: 16.3%). Here, VAF was defined as AF with mitral stenosis or a prosthetic heart valve. AF patients with VHD were older, had more comorbidities with a higher CHADS₂ score, and were prescribed oral anticoagulants more frequently than those without VHD. After adjusting for confounders, VHD was not associated with stroke or systemic embolism, all-cause mortality, or cardiac death. NVAF-VHD was significantly associated with an increased risk of hospitalization for heart failure (adjusted hazard ratio [HR], 1.44; 95% confidence interval [CI], 1.16-1.78), whereas VAF was not (HR, 1.28; 95% CI, 0.86-1.92). Among all types of VHD, aortic valve diseases were associated with a higher risk of cardiac events, whereas mitral valve diseases were not.

CONCLUSIONS

Although VHD did not significantly affect thromboembolism or mortality, it affected cardiac events depending on type, with aortic valve diseases having higher risk, in Japanese patients with AF.

Role of Imaging for Suspected Cardiac Thrombus

PURPOSE OF REVIEW

Cardiac thrombus formation is a frequent complication of a variety of prevalent diseases. Embolism of cardiac thrombus has the potential to result in significant morbidity and mortality from cerebrovascular and peripheral vascular events.

RECENT FINDINGS

Echocardiography is the most commonly used imaging modality for diagnosing intracardiac thrombus. However, technological advances in computed tomography and magnetic resonance imaging have allowed newer noninvasive modalities to evolve into robust tools for the clinical evaluation of patients suspected of disease. Complimentary use of these imaging techniques is crucial in the diagnosis of cardiac thrombus and initiation of anticoagulation therapy.

Gastrointestinal and liver diseases and atrial fibrillation: a review of the literature

Atrial fibrillation (AF) is the most common arrhythmia worldwide and is associated with significant morbidity and mortality. A number of risk factors have been associated with AF, though few studies have explored the association between gastrointestinal and liver diseases and AF. Additionally, AF and treatment for AF may predispose to gastrointestinal and liver diseases. We review the current literature on the bidirectional associations between gastrointestinal and liver diseases and AF. We highlight the gaps in knowledge and areas requiring future investigation.

Prevalence, Characteristics, and Outcomes of Valvular Heart Disease in Patients With Atrial Fibrillation: Insights From the ORBIT-AF (Outcomes Registry for Better Informed Treatment for Atrial Fibrillation)

Background

The presence of valvular heart disease (VHD) may affect the risk of stroke and mortality in patients with atrial fibrillation (AF). Community‐based estimates of prevalence and outcomes of specific forms of VHD in patients with AF are lacking.

Methods and Results

We examined the prevalence of VHD, anticoagulation use, mortality, stroke/transient ischemic attack, and bleeding among a community cohort of patients with AF. Significant VHD was defined as follows: (1) moderate/severe mitral stenosis or mechanical valve; (2) bioprosthetic valve, surgical repair, or balloon valvuloplasty; and (3) moderate/severe aortic regurgitation or stenosis, mitral regurgitation, or tricuspid regurgitation. Proportional hazards models were performed to test the association between VHD groups and outcomes. Among 9748 patients with AF, 2705 (27.7%) had significant VHD. Anticoagulation use was highest among patients with mitral stenosis/mechanical valve (91.8%). Compared with individuals with no significant VHD, individuals with aortic regurgitation/aortic stenosis, mitral regurgitation, or tricuspid regurgitation (hazard ratio, 1.23; 95% confidence interval, 1.07–1.42) had the highest risk of death. There were no differences in stroke or transient ischemic attack and major bleeding among individuals with and without significant VHD. Patients with AF and aortic stenosis had the highest risk of death (hazard ratio, 1.32; 95% confidence interval, 1.08–1.62).

Conclusions

Significant VHD is common among patients with AF in community practice. In a community cohort of patients with AF and CHA₂DS₂‐VASc score ≥2, most were anticoagulated. Individuals with AF and moderate‐to‐severe biological VHD have more comorbidities and a higher mortality risk; however, stroke and major bleeding are similar among those with and without significant VHD.

Percutaneous Left Atrial Appendage Closure: is there a Role in Valvular Atrial Fibrillation

Atrial fibrillation, a chronic and highly morbid cardiovascular condition which affects over 33 million people worldwide, can be broadly categorized as valvular vs non-valvular in etiology. However, definitions of valvular atrial fibrillation have varied widely in the literature, and there is no clear consensus definition to date. Historically, patients with atrial fibrillation in the setting of rheumatic mitral valve disease have constituted a particularly high risk group for cardioembolic stroke, and for this reason many contemporary trials of pharmaceutical and device therapies for atrial fibrillation have systematically excluded patients with valvular heart disease. Therefore, vitamin K antagonism remains the favored approach to mitigate stroke risk in valvular atrial fibrillation, and the optimal strategy to treat atrial fibrillation patients with valvular heart disease who cannot tolerate oral anticoagulation therapy is unknown. Recent trials have demonstrated an important role for percutaneous left atrial appendage occlusion devices in patients with non-valvular atrial fibrillation, but the role of these devices in patients with valvular atrial fibrillation is uncertain. Given the worldwide burden of valvular atrial fibrillation, future trials intended to clarify the role of percutaneous left atrial appendage closure devices in valvular atrial fibrillation should provide important insight for the care of millions of patients.

Cardiovascular Events of Electrical Cardioversion Under Optimal Anticoagulation in Atrial Fibrillation: The Multicenter Analysis

PURPOSE

Electric cardioversion has been successfully used in terminating symptomatic atrial fibrillation (AF). Nevertheless, largescale study about the acute cardiovascular events following electrical cardioversion of AF is lacking. This study was performed to evaluate the incidence, risk factors, and clinical consequences of acute cardiovascular events following electrical cardioversion of AF.

MATERIALS AND METHODS

The study enrolled 1100 AF patients (mean age 60±11 years) who received cardioversion at four tertiary hospitals. Hospitalizations for stroke/transient ischemic attack, major bleedings, and arrhythmic events during 30 days post electric cardioversion were assessed.

RESULTS

The mean duration of anticoagulation before cardioversion was 95.8±51.6 days. The mean International Normalized Ratio at the time of cardioversion was 2.4±0.9. The antiarrhythmic drugs at the time of cardioversion were class I (45%), amiodarone (40%), beta-blocker (53%), calcium-channel blocker (21%), and other medication (11%). The success rate of terminating AF via cardioversion was 87% (n=947). Following cardioversion, 5 strokes and 5 major bleedings occurred. The history of stroke/transient ischemic attack (OR 6.23, 95% CI 1.69-22.90) and heart failure (OR 6.40, 95% CI 1.77-23.14) were among predictors of thromboembolic or bleeding events. Eight patients were hospitalized for bradyarrhythmia. These patients were more likely to have had a lower heart rate prior to the procedure (p=0.045). Consequently, 3 of these patients were implanted with a permanent pacemaker.

CONCLUSION

Cardioversion appears as a safe procedure with a reasonably acceptable cardiovascular event rate. However, to prevent the cardiovascular events, several risk factors should be considered before cardioversion.

A hybrid procedure for atrial fibrillation using total thoracoscopic ablation and post-procedural electrophysiological confirmation of ablation lines

Atrial fibrillation (AF) is the most common chronic arrhythmia in the world, and it is associated with an increased long-term risk of stroke, heart failure, and all-cause mortality. To overcome the limitations of transvenous radiofrequency (RF) ablation for AF, total thoracoscopic ablation (TTA) has evolved as a new technique. TTA has several advantages over transvenous RF ablation and is known to produce better outcomes, especially in patients with persistent AF. Herein, we report 2 cases of successful TTA followed by an electrophysiological study confirming satisfactory ablation lines; the first such procedure reported in Korea.

Patients using vitamin K antagonists show increased levels of coronary calcification: an observational study in low-risk atrial fibrillation patients

AIMS

Vitamin K antagonists (VKA) are currently the most frequently used drug to prevent ischaemic stroke in atrial fibrillation (AF) patients. However, VKA use has been associated with increased vascular calcification. The aim of this study was to investigate the contribution of VKA use to coronary artery calcification in low-risk AF patients.

METHODS AND RESULTS

A prospective coronary calcium scan was performed in 157 AF patients without significant cardiovascular disease (108 males; mean age 57 ± 9 years). A total of 71 (45%) patients were chronic VKA users. The duration of VKA treatment varied between 6 and 143 months (mean 46 months). No significant differences in clinical characteristics were found between patients on VKA treatment and non-anticoagulated patients. However, median coronary artery calcium scores differed significantly between patients without and patients with VKA treatment [0, inter-quartile range (IQR) 0-40, vs. 29, IQR 0-184; P = 0.001]. Mean coronary calcium scores increased with the duration of VKA use (no VKA: 53 ± 115, 6-60 months on VKA: 90 ± 167, and >60 months on VKA: 236 ± 278; P < 0.001). Multivariable logistic regression analysis revealed that age and VKA treatment were significantly related to increased coronary calcium score.

CONCLUSION

Patients using VKA show increased levels of coronary calcification. Age and VKA treatment were independently related to increased coronary calcium score.

Spectrum of CT findings in patients with atrial fibrillation and nontraumatic acute abdomen

OBJECTIVE

The purpose of our study was to review the wide spectrum of pertinent CT findings in patients with acute nontraumatic abdominal pain in the setting of atrial fibrillation.

CONCLUSION

Underlying embolic or hemorrhagic complications are common in patients with acute nontraumatic abdominal pain in the setting of atrial fibrillation and can be accurately seen on CT.

Predicting spontaneous termination of atrial fibrillation based on the RR interval

It is important to characterize conditions under which atrial fibrillation (AF) is likely to terminate spontaneously. A novel method is proposed here. Eleven features are first extracted to characterize RR interval and Poincaré plot from a statistical viewpoint and a geometric viewpoint respectively. Then sequential forward search (SFS) algorithm is utilized for feature selection. Finally, a fuzzy support vector machine (FSVM) with a new fuzzy membership is applied for AF termination prediction. The method is studied with an AF database of electrocardiogram (ECG) recordings provided by PhysioNet for the Cardiology Challenge 2004. It is divided into a training set and two testing sets (A and B). Experiment results show that 100 per cent of testing set A and 100 per cent of testing set B are correctly classified, together with 92.3 per cent of non-terminating and soon-terminating AF correctly classified. It demonstrates that the proposed method can predict spontaneous termination of AF effectively.

Underutilization of Warfarin Therapy in Elderly Patients with Atrial Fibrillation - Fear or False Sense of Security!

Background: Under utilization of warfarin in elderly patients with atrial fibrillation (AF) has been recognized as a significant health care issue. This study examines the rate and reasons for warfarin underutilization in elderly patients with AF at the Kansas City Veterans Affairs Medical Center. Methods: Retrospective study reviewing electronic medical records of all patients aged 65 and older with the diagnosis of atrial fibrillation. Patients on warfarin were excluded. Reasons for not using warfarin were extracted by reviewing the electronic medical record. Anticoagulation indications for these patients were determined based on the ACC/AHA/ESC 2006 Guidelines for the Management of Patients with Atrial Fibrillation. Results: Warfarin was not used by 407 patients (25%) with known AF. Average age was 79+6.2 years. 60% of patients had persistent or permanent AF. Prevalence of risk factors for thromboembolism included hypertension (74%), heart failure or ejection fraction of <40% (21%), diabetes (27%) and coronary artery disease (48%). CHADS (2) scores were documented in the charts less than 1% of the times. Only 11 patients had CHADS (2) score of 0 and 70 had a score of 1. A class I or IIa indication for warfarin therapy was present in 298 (73%) of patients. Return to sinus rhythm (37%) was the most common reason for not using warfarin. In 30% of cases the reason not to use warfarin was not addressed. Other reasons not to use warfarin included fear of falls (7%), prior head or GI bleed (14%), patient refusal & noncompliance (12%). History of CVA or TIA was documented in 12% of patients. Conclusions: Underutilization of warfarin in elderly patients with atrial fibrillation remains a common problem despite their high risk for thromboembolic events. A false sense of security about the paroxysmal nature of AF, lack of proper insight about stroke risk (CHADS (2)), and fear of bleeding are the most common reasons for non use of warfarin.

Atrial fibrillation is associated with lower cognitive performance in the Framingham offspring men

The purpose of this study was to investigate the association of atrial fibrillation (AFIB) with multiple measures of cognitive performance in a large community-based sample extensively characterized for vascular risk factors. Our primary analysis included 1011 Framingham Offspring Study (Framingham, Mass) men, mean age = 61.0 (37-89) years, free of clinical stroke and dementia. Using multivariable linear regression models, we related the presence (n = 59) versus absence (n = 952) of AFIB in men to a global measure of performance and multiple measures of specific cognitive abilities assessed an average of 8 months after the AFIB surveillance period. Adjusting for age, education, multiple cardiovascular risk factors, and cardiovascular disease, men with AFIB exhibited significantly lower mean levels of cognitive performance compared with men in normal sinus rhythm. Men with AFIB exhibited lower performance on global cognitive ability and cognitive abilities including Similarities (abstract reasoning), Visual Reproductions-Immediate Recall, Visual Reproductions-Delayed Recall, Visual Organization, Logical Memory-Delayed Recall, and Trail Making A (scanning and tracking) and Trail Making B (scanning, tracking, and executive functioning). Further studies leading to a better understanding of the mechanisms underlying the relation between AFIB and cognitive performance are important.

The D-dimer assay: a possible tool in the evaluation of atrial thrombosis

Atrial fibrillation (AF) is a common arrhythmia seen in clinical practice, and affects more than 4% of the population older than 60 years of age. Peripheral thromboembolism contributes significantly to the observed morbidity and mortality. Symptomatic AF, before cardioversion to normal sinus rhythm, requires either exclusion of atrial thrombi using transesophageal echocardiography (TEE) or the conventional use of three weeks of adequate anticoagulation. The exclusion of atrial thrombi by TEE, a nontomographic technique but comparable with conventional treatment of AF in outcomes, has inherent limitations due to the complex three-dimensional multilobed anatomy of the left atrial appendage, where the majority of atrial thrombi arise. Also, the conventional treatment of three weeks of therapeutic anticoagulation before cardioversion reportedly does not always eliminate atrial thrombi. Plasma D-dimer constitutes an antigen-antibody reaction to the dimeric final degradation product of a mature clot. An elevated fibrin D-dimer has a high sensitivity for intravascular thrombosis and, hence, may improve the evaluation of a patient with AF before cardioversion in addition to a TEE. A case is presented in which a positive D-dimer resulted in performing TEE to document atrial thrombosis and the complications of previous bacterial endocarditis. In the present case, this involved aortic root abscess formation and acute aortic regurgitation because of flailing of the noncoronary cusp that resulted in recurrent pulmonary edema.

The effect of VVI pacing on P-wave dispersion in patients with dual-chamber pacemakers

The incidence of atrial fibrillation is higher in patients with VVI pacing mode than DDD pacing mode, but the likely mechanism is not clearly understood. We aimed to evaluate whether short-term VVI pacing increases inhomogeneous atrial conduction by using P-wave dispersion. Forty-seven patients (32 men, 15 women, mean age 54 +/- 13 years) with DDD pacemakers were enrolled in this study. Twelve-lead surface ECGs were obtained in all patients during VDD pacing after an observation period of 1 week. The mode was then changed to VVI and 12 lead surface ECGs were obtained after another 1-week observation period. P-wave durations were calculated in all 12 leads in both VDD and VVI pacing modes. The difference between the maximum and the minimum P-wave duration was defined as the P-wave dispersion (PWD = P(max) - P(min)). P-wave maximum duration (P(max)) calculated in VVI pacing mode was significantly longer than in VDD pacing mode (128 +/- 19 vs 113 +/- 16 ms, P < 0.001). There was no significant difference in the P-wave minimum durations (80 +/- 13 ms vs 79 +/- 12 ms, P = 0.7) between VVI pacing and VDD pacing. The P-wave dispersion value was higher in the VVI pacing mode than in the VDD pacing mode (48 +/- 8 ms vs 34 +/- 7 ms, P < 0.001). Short-term VVI pacing induces prolongation of P(max) and results in increased P-wave dispersion, which might be responsible for the development of atrial fibrillation more frequently in these patients than in those with the VDD pacing mode.

Warfarin for Stroke Prevention in Octogenarians with Atrial Fibrillation

The authors examined warfarin use in elderly patients with atrial fibrillation. Medical records were abstracted from a random sample of Medicare beneficiaries with atrial fibrillation who were discharged from Kansas hospitals. Data were analyzed for warfarin and aspirin use and risk factors for stroke or bleeding in patients 65-79 years of age or 80 years and older. Stroke risk factors other than age and atrial fibrillation were seen in 98% of 142 patients less than 80 years of age and 100% of 141 octogenarians. Warfarin use was similar in the younger and older age groups (50% vs. 45%, respectively; p = ns) and was not associated with the number of stroke or bleeding risk factors. Compared to patients less than 80 years of age, octogenarians were less likely to receive aspirin (38% vs. 27%, respectively; p < 0.05). Anticoagulation rates for high-risk patients with atrial fibrillation were low and poorly explained by stroke or bleeding risks.

The frequency analysis of signal-averaged ECG of P wave as predictor of efficacy of class III antiarrhythmic drugs to maintain sinus rhythm in recurrent idiopathic atrial fibrillation

BACKGROUND

The use of class III antiarrhythmic drugs (ADIII) has been considered a good predictor of sinus rhythm in patients post-cardioversion from atrial fibrillation (AF). Several studies using frequency domain analysis of signal-averaged ECG (FDSAECG) of the P wave were able to identify patients at risk for AF. The aim of this study was to assess the FDSAECG in predicting recurrence of idiopathic persistent AF (IPAF) in patients under ADIII therapy.

METHODS

In 33 patients with two or more previous symptomatic episodes of IPAF, despite classes I and II therapy, the FDSAECG of the P wave was performed during sinus rhythm and free-drug state. The parameters were the mean and standard deviation of the frequency intersegmentar spectral correlation and the standard deviation of the signal frequency edge track. During the follow-up of 30 +/- 18 months, all patients received either amiodarone or sotalol.

RESULTS

During the follow-up, the patients were divided into two groups: Group I-frequent recurrence (>or= three events/year; 16 patients), and Group II-infrequent recurrence (< three events/year; 17 patients). With appropriate cutoff points for each parameter analyzed, intense fragmented electrical activity defined by the presence of at least two abnormal criteria were observed in 13 of 16 patients group I and in 3 of 17 patients group II (P = 0.0003). Sensitivity, specificity, positive and negative predictive values for frequent recurrence were 81.3, 82.4, 81.3, and 82.4, respectively.

CONCLUSIONS

The results suggested that FDSAECG analysis of the P wave accurately predicted patients whose ADIII therapy will be effective in maintaining the sinus rhythm without frequent recurrence of IPAF.

Optimising stroke prevention in non-valvular atrial fibrillation

Atrial fibrillation is associated with substantial morbidity and mortality. Pooled data from trials comparing antithrombotic treatment with placebo have shown that warfarin reduces the risk of stroke by 62%, and that aspirin alone reduces the risk by 22%. Overall, in high-risk patients, warfarin is superior to aspirin in preventing strokes, with a relative risk reduction of 36%. Ximelagatran, an oral direct thrombin inhibitor, was found to be as efficient as vitamin K antagonist drugs in the prevention of embolic events, but has been recently withdrawn because of abnormal liver function tests. The ACTIVE-W (Atrial Fibrillation Clopidogrel Trial with Irbesartan for Prevention of Vascular Events) study has demonstrated that warfarin is superior to platelet therapy (clopidogrel plus aspirin) in the prevention af embolic events. Idraparinux, a Factor Xa inhibitor, is being evaluated in patients with atrial fibrillation. Angiotensin-converting enzyme inhibitors and angiotensin II receptor-blocking drugs hold promise in atrial fibrillation through cardiac remodelling. Preliminary studies suggest that statins could interfere with the risk of recurrence after electrical cardioversion. Finally, percutaneous methods for the exclusion of left atrial appendage are under investigation in high-risk patients.

Spectral turbulence analysis of the signal-averaged electrocardiogram of the atrial activation as predictor of recurrence of idiopathic and persistent atrial fibrillation

The frequency domain analysis of the P-wave signal-averaged ECG (P-SAECG) is able to identify patients at risk for lone atrial fibrillation (AF) after cardioversion to sinus rhythm. The terminal portion of the P-wave of right precordial leads on 12-lead ECG is associated with electrical abnormalities in the atria. The aim of this study was to assess the spectral turbulence analysis (STA) of the P-SAECG as a predictor of recurrence of idiopathic AF. STA was performed in 41 patients with 2 or more symptomatic episodes of idiopathic and persistent AF after successful electrical cardioversion and drug-free state (Group A), and in 25 control individuals during sinus rhythm (Group B), matched by age, gender, and P-wave duration. The orientation of the terminal portion (positive or negative) of the Z-lead was assessed as representing right precordial leads potentials. After 6 months follow-up, Group A was divided into two groups according to recurrence: G-A1--at least one recurrence (21 patients), and G-A2--no recurrence (20 patients). Fragmented electrical activity (FEA) was observed in 19 patients of G-A1 and in 2 of G-A2 (odds ratio = 85.5; p<<0.001). STA showed 90.5% sensitivity and 90.0% specificity for early recurrence of AF. After 12 months, no patients of G-A2 and 15 of G-A1 developed >3 episodes of persistent AF, being FEA observed in 13 (odds ratio = 14.6, p = 0.002). No episodes of AF were observed in Group B. Average time for recurrence of FEA positive patients (4.3 +/- 0.7 months) was significantly shorter than of G-A2 (7.4+/-0.7 months), and log-rank analysis revealed significant difference of event-free rate over time (p = 0.004). In a logistic regression model FEA, use of amiodarone and a positive terminal portion of the Z-lead of the P-SAECG were independent predictors of recurrence of idiopathic and persistent AF.