Left atrial appendage occlusion for stroke prevention in patients with atrial fibrillation

The most severe consequence of atrial fibrillation (AF) is a cardioembolic stroke. The incidence of cardioembolic stroke increases significantly in patients with AF. Although warfarin has been the mainstay of the prevention of cardioembolic stroke, there are several limitations to the use of warfarin that hinder its effectiveness. This article provides the historical development of devices that exclude the left atrial appendage, their effectiveness and potential patient selection, as an alternative to warfarin and the novel oral anticoagulation therapy for the prevention of cardioembolic stroke in patients with AF.     

Recommendations for thromboprophylaxis in the 2012 focused update of the ESC guidelines on atrial fibrillation: a commentary

The objective of this article is to provide a commentary on the recommendations for stroke prevention from the 2012 focused update of the European Society of Cardiology guidelines on the management of atrial fibrillation and the evidence (or lack of it) supporting these recommendations. These guidelines strongly advocate a major clinical practice shift towards initially focusing on the identification of ‘truly low risk’ patients who do not need any antithrombotic therapy. After this initial decision‐making step, effective stroke prevention – that is, oral anticoagulation therapy (whether as well‐controlled adjusted dose warfarin or with one of the novel oral anticoagulants) – could be offered to patients with atrial fibrillation with ≥ 1 stroke risk factors. The 2012 focused update guideline also provides additional guidance on advances in stroke and bleeding risk assessment that are evident since publication of the 2010 guideline, as well as recommendations on the use of the novel oral anticoagulants and the left atrial appendage occlusion devices that have been increasingly used in European clinical practice over the last 2 years.     

Balancing bleeding and thrombotic risk with new oral anticoagulants in patients with atrial fibrillation

Atrial fibrillation (AF) markedly increases the risk of stroke. Warfarin is highly effective for the prevention of stroke in such patients, but it is difficult to use and causes bleeding. Three new oral anticoagulants have been approved for stroke prevention in AF patients, and are at least as effective as warfarin with better bleeding profiles. These new agents have changed and simplified our approach to stroke prevention, as the threshold for initiation of oral anticoagulation is lower. All patients with AF should be risk assessed using the CHA₂DS₂-VASc score, and all patients with a score of 1 or above (except women with female sex as their only risk factor on the CHA₂DS₂-VASc score) should be considered for oral anticoagulation with one of the new agents. Formal bleeding risk assessment is essential, and can be done by using the well-validated HAS-BLED score.     

Continuous versus intermittent monitoring of ventricular rate in patients with permanent atrial fibrillation

Background: Ventricular rate control (VRC) is an important treatment strategy for patients with permanent atrial fibrillation (AF). We assessed the prevalence of poor VRC and the adequacy of various intermittent monitoring regimens to accurately characterize VRC during permanent AF. Methods: We retrospectively analyzed data from dual chamber implantable cardioverter defibrillator (ICD) and cardiac resynchronization therapy defibrillator (CRT‐D) patients in the Medtronic Discovery? Link having permanent AF (AF burden >23 hours/day) and ≥365 consecutive days of device data. Poor VRC was defined as a day with the mean ventricular rate during AF >100 beats/minute (bpm) for ICD patients and >90 bpm for CRT‐D patients. Intermittent monitoring regimens were simulated from continuous device data by randomly selecting subsets of days in which data were available for analysis. Assessments of poor VRC were computed after replicating 1,000 simulations. Results: ICD (n = 1,902, age = 71 ± 10) and CRT‐D (n = 3,397, age = 72 ± 9) patients were included and followed for 365 days. The prevalence of poor VRC was 24.8% among ICD patients and 28.6% among CRT‐D patients. Significantly more patients were identified as having poor VRC with continuous monitoring compared to all intermittent monitoring regimens (sensitivity range = 8%–31%). Furthermore, 11.6% of ICD patients and 17.9% of CRT‐D patients experienced ≥7 days with poor VRC, to which the sensitivities of annual 7‐ and 21‐day recordings were <7% and <20%, respectively. Conclusions: A significant proportion of permanent AF patients experience poor VRC that would be missed with random intermittent monitoring. Whether improved knowledge of VRC with continuous monitoring will lead to improved outcomes compared to intermittent monitoring requires further study. (PACE 2012;1–7)     

Asymptomatic atrial fibrillation in pacemaker recipients: incidence, progression, and determinants based on the atrial high rate trial

BACKGROUND: The epidemiology and clinical implications of asymptomatic atrial tachyarrhythmias (AT) including both atrial fibrillation and flutter in pacemaker recipients with and without arrhythmia history are not well understood. The Atrial High Rate Episodes (A-HIRATE) in Pacemaker Patients Trial was designed to identify and compare the incidence of AT in patients with and without previously diagnosed AT and a standard indication for dual chamber pacing, and to provide useful diagnostic information for clinical management. METHODS: Four hundred twenty-seven patients were implanted with a pacemaker (Kappa 7-900, Medtronic, Inc., Minneapolis, MN, USA) capable of detecting and storing multiple atrial high rate episodes (AHRE) and followed for 2 years. Group I included 331 patients without prior history of AT and Group II included 96 patients with prior AT history. RESULTS: Pacemaker diagnostics appropriately detected 93% of reviewed AHRE. The rate of occurrence of first AHRE was significantly higher (P < 0.0001) in Group II patients, as was average AHRE burden. The rate of first AHRE occurrence was 88.6% for patients in Group II and 53.8% in Group I at 24 months post-implant. The rate of AHRE occurrence was similar in both groups after the first month post-implant. The majority of stored AHRE were asymptomatic; symptoms did not correspond to an actual AHRE in most patients. CONCLUSIONS: The incidence of AT in pacemaker recipients is high. Most device-detected AHRE are asymptomatic. Prior history of AT is associated with higher arrhythmia burden. AHRE diagnostics have a high positive predictive value for identifying AT events.     

Clinical outcomes of acute stroke patients with atrial fibrillation

Evaluation of: Kazumi K, Yasuyuki I, Kensaku S, Takeshi I, Shinji Y, Junya A. IV-tPA therapy in acute stroke patients with atrial fibrillation. J. Neurol. Sci. 276(1–2), 6–8 (2009).

Stroke is the leading cause of disability and the second most common cause of death worldwide. The care and treatment of stroke patients have evolved over the last two decades, with increasing use of thrombolysis (e.g., intravenous tissue plasminogen activator in acute stroke patients), which has improved survival and recovery following stroke. The article under evaluation offers a greater insight into the relationship of clinical outcome of stroke and atrial fibrillation after tissue plasminogen activator infusion.     

超声心动图用于非瓣膜病性心房颤动患者卒中危险分层

目的观察超声心动图用于非瓣膜病性心房颤动(NVAF)患者卒中危险分层的价值。方法根据CHA₂ DS₂-VASc评分将90例NVAF患者分为低危组(17例)、中危组(40例)及高危组(33例),对比其血清脑钠肽(BNP)、肌钙蛋白Ⅰ(TnⅠ)及超声参数左心房前后径(LAD)、左心房容积指数(LAVI)、二尖瓣口舒张期流速(E)、二尖瓣环舒张期运动速度(e’)和左心耳(LAA)排空速度(V LAA)、口部直径(D 1)、内侧壁应变(S内)和外侧壁应变(S外)等。结果高危组BNP明显高于中、低危组(P均<0.05),高危组TnⅠ明显高于低危组(P<0.05)。高危组LAVI明显高于中危组(P<0.05),中危组LAVI明显高于低危组(P<0.05);高危组LAD、e’及E/e’均明显大于低危组(P均<0.05)。高危组V LAA明显低于中、低危组(P均<0.05),中危组V LAA明显低于低危组(P<0.05);高危组D 1、S内及S外均明显高于低危组(P均<0.05)。结论超声心动图LAVI、V LAA和LAA应变等参数对于NVAF患者卒中危险分层具有一定临床应用价值。     

Risk of stroke after surgery in patients with and without chronic atrial fibrillation

Summary. Background: The extent to which chronic atrial fibrillation affects the risk of postoperative stroke is largely unknown. Objectives: We sought to determine the 30‐day rate of stroke among patients with and without chronic AF who underwent 10 different types of surgery. Patients/methods: The crude incidence of stroke was retrospectively determined using a population‐based linked administrative database of hospitalized patients who underwent specified operations between 1 January 1996 and 30 November 2005. The risk of stroke in patients with AF was adjusted for age, race, sex, presence of diabetes, heart failure, hypertension and prior stroke. Results: The overall 30‐day rate of stroke in 69 202 patients with chronic AF was 1.8% (95% CI, 1.7–1.9%) vs. 0.6% (CI, 0.58–0.62%) in 2 470 649 patients without AF. The risk‐adjusted odds of a postoperative stroke in patients with chronic AF were 2.1 (CI, 2.0–2.3). The highest incremental difference in the crude rate of stroke was observed in patients undergoing neurologic or vascular surgery, with a difference of approximately 2%. Conclusion: Patients with chronic AF had twice the risk of postoperative stroke. Randomized trials are needed to determine if aggressive perioperative anticoagulation can reduce the incidence of postoperative stroke in patients with AF.     

Clinical significance of the atrial fibrillation threshold in patients with paroxysmal atrial fibrillation

AF threshold and the other electrophysiological parameters were measured to quantify atrial vulnerability in patients with paroxysmal atrial fibrillation (PAF, n = 47), and those without AF (non-PAF, n = 25). Stimulations were delivered at the right atrial appendage with a basic cycle length of 500 ms. The PAF group had a significantly larger percentage of maximum atrial fragmentation (%MAF, non-PAF: mean +/- SD = 149 +/- 19%, PAF: 166 +/- 26%, P = 0.009), fragmented atrial activity zone (FAZ, non-PAF: median 0 ms, interquartile range 0-20 ms, PAF: 20 ms, 10-40 ms, P = 0.008). Atrial fibrillation threshold (AF threshold, non-PAF: median 11 mA, interquartile range 6-21 mA, PAF: 5 mA, 3-6 mA, P < 0.001) was smaller in the PAF group than in the non-PAF group. Sensitivity, specificity, and positive predictive value of electrophysiological parameters were as follows, respectively: %MAF (cut off at 150%, 78%, 52%, 76%), FAZ (cut off at 20 ms, 47%, 84%, 85%), AF threshold (cut off at 10 mA, 94%, 60%, 81%). There were no statistically significant differences between the non-PAF and PAF groups in the other parameters (effective refractory period, interatrial conduction time, maximum conduction delay, conduction delay zone, repetitive atrial firing zone, wavelength index), that were not specific for PAF. In conclusion, the AF threshold could be a useful indicator to evaluate atrial vulnerability in patients with AF.     

Prediction of conversion from paroxysmal to permanent atrial fibrillation

BACKGROUND: Paroxysmal atrial fibrillation (PAF) transits to permanent atrial fibrillation (PEAF). The current study was to determine whether a P wave-triggered P wave signal averaged electrocardiogram (P-SAECG) and chemoreflexsensitivity (CHRS) are useful to predict a conversion to PEAF in patients with PAF. METHODS: The filtered P wave duration (FPD) and the root mean square voltage of the last 20 ms of the P wave (RMS 20) were measured by P-SAECG. The ratio between the difference of RR intervals in the ECG and venous pO2 before and after 5-minutes oxygen inhalation is measured (ms/mmHg) for the determination of CHRS. Results: A total of 180 patients with PAF were enrolled and followed for a mean of 22.5 months. PEAF occurred in 38 patients (21%) and these patients had a significantly larger left atrial size (43.2 +/- 4.9 vs. 41.0 +/- 5.4 mm, P = 0.021), a significantly longer FPD (158.8 +/- 18.2 vs. 136.7 +/- 16.6 ms, P < 0.0001), and a significantly lower CHRS (1.96 +/- 0.99 vs. 2.44 +/- 1.19 ms/mmHg, P = 0.024) than patients with PAF. Patients with PEAF tended to have a lower RMS 20 (2.38 +/- 0.65 vs. 2.75 +/- 1.18 microV, P = 0.067) than patients with PAF. The chi(2) test showed that the combination of FPD > or = 145 ms, RMS 20 < or = 3.0 microV, left atrial size > or = 41 mm, and CHRS < or = 2.0 ms/mmHg had the best predictive power for PEAF. Patients who fulfilled these criteria had a 12-fold increased risk for a conversion from PAF to PEAF. CONCLUSIONS: Our results show that a P-SAECG, an analysis of CHRS, and left atrial enlargement are clinical predictors of a progression from PAF to PEAF.     

Value of pacemaker atrial diagnostic data in patients with paroxysmal atrial fibrillation: an opportunity to improve rates of warfarin utilization

Atrial diagnostic data within implantable devices provide an opportunity to assess the frequency and quantity of atrial fibrillation (AF) episodes (AF burden) and its impact on appropriate warfarin anticoagulation. Cardiologists were given clinical scenarios to review with different types of pacemaker diagnostic data in an elderly patient with risk factors for stroke. AF specific data was associated with increased warfarin utilization, but only at intermediate rates. Potential reasons and clinical implications are discussed.     

Atrial fibrillation in patients with first-ever stroke: frequency, antithrombotic treatment before the event and effect on clinical outcome

BACKGROUND AND PURPOSES: Atrial fibrillation (AF) is an independent risk factor for stroke. The aims of this study were to assess: (i) the frequency of known or unknown AF in patients admitted to the hospital for a first-ever ischemic stroke and whether AF is associated with an adverse outcome at discharge (death or disability); (ii) the rates and determinants for the use of antithrombotic agents before stroke in patients with known AF and the adherence to the current treatment guidelines; and (iii) whether the lack of adherence to the current guidelines is associated with adverse outcome at discharge. METHODS: Consecutive patients with acute first-ever stroke admitted to an individual Stroke Unit between January 2000 to December 2003, were included in the study. Twelve-lead electrocardiogram (ECG) was performed in all patients on admission. Functional outcome was measured at discharge according to modified Rankin Score. RESULTS: A total of 1549 patients were included in the study: 238 patients (15.4%) were known to have AF and 76 (4.9%) were diagnosed with AF (unknown) on ECG performed on admission. At discharge 91 patients (5.9%) had died and 605 patients (39.0%) had died or were functionally dependent. Multivariate analysis showed that AF on admission was correlated with mortality or disability (OR = 1.58, 95% CI 1.09-2.30, P = 0.015). Before stroke, 124 out of 238 patients with known AF (52.1%) were not on antithrombotic therapy, 83 (34.9%) were receiving antiplatelet and 31 (13.0%) anticoagulant treatment. Previous transient ischemic attack, history of ischemic heart disease and hyperlipidemia were associated with the use of antithrombotic therapy. Only 24 out of 114 patients on antithrombotic treatment on admission were adequately treated according to the current guidelines. Of the adequately treated patients, 41.7% died or were disabled at discharge respect to 52.3% of the patients non-adequately treated (RR = 0.80, 95% CI 0.48-1.30). CONCLUSIONS: AF (on history or new diagnosis) was present in 20.3% of the patients with first-ever stroke admitted to a Stroke Unit and it was associated with increased mortality or disability. Only 10% of patients with known AF were previously receiving an adequate antithrombotic treatment according to current guidelines.     

Combination of clopidogrel and aspirin for reduction of vascular events in patients with atrial fibrillation

Evaluation of: The ACTIVE Investigators. Effect of clopidogrel added to aspirin in patients with atrial fibrillation. N. Engl. J. Med. 360(20), 2066–2078 (2009).

Atrial fibrillation (AF) is the most common heart rhythm disorder and increases the risk for stroke by fivefold. Therefore, antithrombotic pharmacological agents are recommended and commonly used to prevent stroke and thromboembolic vascular events in patients with AF. Although, aspirin is an effective and acceptable agent for low-risk patients, oral vitamin K antagonists anticoagulants have superiority over aspirin in patients with AF who are at high risk for complications. However, given several practical impediments, vitamin K antagonists may not be suitable for certain high-risk patients with AF. It is not unusual for clinicians to encounter situations where selection of appropriate pharmacotherapy options for stroke prevention may be quite challenging in high-risk patients with AF who are deemed to be unsuitable candidates for oral anticoagulants. It may be hypothesized that, in such a situation, a combination of clopidogrel with aspirin, possibly by their additive effect in the prevention of platelet-mediated thrombosis may be used effectively instead of oral anticoagulants. In this article, we have discussed this issue and review one of the recently published Atrial Fibrillation Clopidogrel Trial with Irbesartan for Prevention of Vascular Events (ACTIVE) studies, the ACTIVE-A trial, in which the treatment strategies utilizing ‘clopidogrel plus aspirin’ and ‘aspirin alone’ in patients with AF who were at increased risk for stroke and for whom therapy with a vitamin K antagonist was considered unsuitable were compared.     

体外电复律治疗房颤对植入左心耳封堵器患者的影响

目的：探讨植入左心耳封堵器的房颤患者接受体外电复律治疗的可行性和安全性。方法：选取2016年5月至2019年12月北京医院收治的经皮成功植入左心耳封堵器患者51例，其中接受体外电复律治疗7例（13.7%），观察电复律对装置的影响及相关不良事件。结果：51例患者中，接受电复律治疗的7例（13.7%）患者未发生封堵器移位或脱落，围手术期未发生严重不良事件。结论：植入左心耳封堵器的房颤患者接受体外电复律治疗是安全、可行的。     

Ximelagatran for stroke prevention in atrial fibrillation

Atrial fibrillation is the most common sustained cardiac arrhythmia and the most frequently encountered cause of embolic stroke. Vitamin K antagonists (such as warfarin) have represented the cornerstone of anticoagulation practice for the last 60 years. Although highly effective in preventing thromboembolic events among patients with atrial fibrillation, warfarin therapy is limited by a multitude of potential problems. Hence, warfarin is significantly underused in clinical practice, with only half of warfarin-treated patients actually achieving therapeutic anticoagulation in routine clinical practice. Consequently, there is an overwhelming need for an alternative oral anticoagulant for patients with atrial fibrillation that is safer, more practical and effective. Ximelagatran (Exanta®, AstraZeneca) is a novel oral direct thrombin inhibitor that is rapidly converted to the active compound melagatran after oral absorption. It has a low potential for drug interactions, anticoagulation monitoring is not required, and it is administered at a fixed twice-daily dose. The Stroke Prevention using the ORal Thrombin Inhibitor in patients with nonvalvular atrial Fibrillation (SPORTIF) III and V trials have together demonstrated the noninferiority of ximelagatran relative to warfarin for the prevention of stroke and embolic events in atrial fibrillation. Unfortunately, initial optimism has been tempered by serious concerns over its safety data in view of its propensity to cause elevation in liver enzymes.