A tailored treatment strategy: a modern approach for stroke prevention in patients with atrial fibrillation

The main priority in atrial fibrillation (AF) management is stroke prevention, following which decisions about rate or rhythm control are focused on the patient, being primarily for management of symptoms. Given that AF is commonly associated with various comorbidities, risk factors such as hypertension, heart failure, diabetes mellitus and sleep apnoea should be actively looked for and managed in a holistic approach to AF management. The objective of this review is to provide an overview of modern AF stroke prevention with a focus on tailored treatment strategies. Biomarkers and genetic factors have been proposed to help identify ‘high‐risk’ patients to be targeted for oral anticoagulation, but ultimately their use must be balanced against that of more simple and practical considerations for everyday use. Current guidelines have directed focus on initial identification of ‘truly low‐risk’ patients with AF, that is those patients with a CHA₂DS₂‐VASc [congestive heart failure, hypertension, age ≥75 years (two points), diabetes mellitus, stroke (two points), vascular disease, age 65–74 years, sex category] score of 0 (male) or 1 (female), who do not need any antithrombotic therapy. Subsequently, patients with ≥1 stroke risk factors can be offered effective stroke prevention, that is oral anticoagulation. The SAMe‐TT₂R₂ [sex female, age <60 years, medical history (>2 comorbidities), treatment (interacting drugs), tobacco use (two points), race non‐Caucasian (two points)] score can help physicians make informed decisions on those patients likely to do well on warfarin (SAMe‐TT₂R₂ score 0–2) or those who are likely to have a poor time in therapeutic range (SAMe‐TT₂R₂ score >2). A clinically focused tailored approach to assessment and stroke prevention in AF with the use of the CHA₂DS₂VASc, HAS‐BLED [hypertension, abnormal renal/liver function (one or two points), stroke, bleeding history or predisposition, labile international normalized ratio, elderly (>65 years) drugs/alcohol concomitantly (one or two points)] and SAMeTT₂R₂ scores to evaluate stroke risk, bleeding risk and likelihood of successful warfarin therapy, respectively, is discussed.     

Transient atrial fibrillation induced by adenosine in a patient with atrial tachycardia

The administration of adenosine during atrial tachycardia usually terminates the arrhythmia or induces AV block and makes the diagnosis clear. We present a patient with atrial tachycardia in which the administration of adenosine induced a transient atrial fibrillation (AF). A continuous transition between both arrhythmias was observed and the original tachycardia persisted after the termination of the AF. This proarrhythmic effect may be due to the adenosine-mediated shortening of the atrial refractory periods, which produces a decreased wavelength of the reentry circuits and the potential coexistence of several wave-fronts in the atria, favoring the development of AF. The recognition of this uncommon effect is important, since the repeated administration of increasing doses of adenosine may induce sustained AF.     

Swallowing induced atrial tachycardia and fibrillation in a patient with a Wolf-Parkinson-White syndrome

A 56-year-old man with the Wolf-Parkinson-White (WPW) syndrome (type A) is described. His presenting signs were paroxysmal atrial tachycardia and fibrillation induced by swallowing. This supraventricular tachyarrhythmia (SVT) could be abolished by performing the valsalva maneuver or carotid stimulation, and prevented only by treatment with amiodarone.     

心房颤动消融术后房性心动过速

随着射频导管消融治疗心房颤动（atrial fibrillation,AF）的广泛开展,AF患者选择范围逐渐扩大,而消融策略也更为激进。尽管技术策略渐趋成熟,AF消融导致的其他类型并发症似有下降趋势,但消融术后的房性心动过速（atrial tachycardia,AT）却愈加常见,并成为棘手的临床问题。AT的处理和最终治愈已成为导管消融治疗AF的一部分,     

Canadian Cardiovascular Society atrial fibrillation guidelines 2010: prevention and treatment of atrial fibrillation following cardiac surgery

Postoperative atrial fibrillation and atrial flutter (POAF) are the most common complications of cardiac surgery that require intervention or prolong intensive care unit and total hospital stay. For some patients, these tachyarrhythmias have important consequences including patient discomfort/anxiety, hemodynamic deterioration, cognitive impairment, thromboembolic events including stroke, exposure to the risks of antiarrhythmic treatments, longer hospital stay, and increased health care costs. We conclude that prevention of POAF is a worthwhile exercise and recommend that the dominant therapy for this purpose be β-blocker therapy, especially the continuation of β-blocker therapy that is already in place. When β-blocker therapy is contraindicated, amiodarone prophylaxis is recommended. If both of these therapies are contraindicated, therapy with either intravenous magnesium or biatrial pacing is suggested. Patients at high risk of POAF may be considered for first-line amiodarone therapy, first-line sotalol therapy, or combination prophylactic therapy. The treatment of POAF may follow either a rate-control approach (with the dominant therapy being β-blocking drugs) or a rhythm-control approach. Anticoagulation should be considered if persistent POAF lasts >72 hours and at the point of hospital discharge. The ongoing need for any POAF treatment (including anticoagulation) should be reconsidered 6-12 weeks after the surgical procedure.     

New treatment options for stroke prevention in atrial fibrillation

Optional statement Atrial fibrillation (AF) is the most common arrhythmia requiring treatment. Its most devastating consequence is thromboembolic stroke. Therapy with warfarin is indicated in most patients, as it has been shown conclusively to reduce the risk of stroke. Aspirin is an inferior alternative except in certain low-risk patients or for patients with an absolute contraindication to warfarin. Guidelines have been published for the administration of antithrombotic therapy in AF, but many patients who are candidates for anticoagulation do not receive this therapy. Even as this therapy is under-utilized, the indication for anticoagulation is expanding. Indefinite continuation of anticoagulation should be considered in higher-risk patients despite the appearance that sinus rhythm has been restored because asymptomatic (or silent) AF occurs frequently. Newer agents that offer substantial benefit over warfarin are being developed and would enhance compliance with anticoagulation in AF if these novel therapies prove to be safe and equivalent to warfarin in efficacy.     

Discrimination of ventricular tachycardia from sinus tachycardia and atrial fibrillation in a tiered-therapy cardioverter-defibrillator

Objectives. This study was conducted to evaluate criteria for discrimination of ventricular tachycardia from atrial fibrillation and sinus tachycardia in a tiered-therapy cardioverterdefibrillator (Medtronic PCD).Background. Interval stability algorithms discriminate ventricular tachycardia from atrial fibrillation. Onset algorithms discriminate ventricular tachycardia from sinus tachycardia. Neither has been validated clinically.Methods. The stability criterion requires that a ventricular tachycardia interval not vary fron any of the three previous intervals by more than the programmable stability value. The onset criterion detects initiation of ventricular tachycardia only if the ratio of an interval to the mean of four previous intervals is less than a programmed onset ratio andeither the second or third preceding interval exceeds the ventricular tachycardia detection interval.We evaluated these criteria in 100 patients at electrophysiologic study and exercise testing (65 patients) and during a mean (±SD) follow-up of 16.2 ± 7.9 months. The PCDs were programmed to tiered therapy in 54 patients. In the remaining 46 patients, the PCD's memory for detected ventricular tachycardia was used to study the specificity of the chosen onset criterion for rejecting sinus tachycardia. We used stored intervals preceding appropriate (n = 99) and inappropriate (n = 54) detections to test a new onset criterion that was less sensitive to a single index interval.Results. Programmed stability of 40 ms decreased detection of induced atrial fibrillation by 95% (20 patients), paroxysmal atrial fibrillation by 95% (6 patients) and chronic atrial fibrillation by 99% (9 patients); all episodes of spontaneous (n = 877) and induced (n = 339) ventricular tachycardia were detected. A programmed onset ratio of 87% rejected sinus acceleration (98%) but caned underdetection of 0.5% of ventricular tachycardias. The onset criterion permitted inappropriate detection of premature ventricular complexes during sinus tachycardia, but the new criterion reduced these inappropriate detections by 98%.Conclusions: The PCD's onset and stabillty criteria reduced inappropriate detection of atrial fibrillation and sinus acceleration while detecting 99.5% of ventricular tachycardias.     

Flecainide-induced ventricular tachycardia and fibrillation in patients treated for atrial fibrillation

Flecainide acetate has a recognized proarrhythmic effect in patients treated for ventricular tachycardia. Three patients developed severe ventricular arrhythmias while taking flecainide for atrial fibrillation. Patient 1 had normal ventricular function and idiopathic atrial fibrillation. Treadmill exercise tests during digoxin therapy showed no ventricular arrhythmia; however, during flecainide therapy the patient developed ventricular flutter at his peak exercise level that required cardioversion. Patient 2 had normal ventricular function and a prosthetic mitral valve. During therapy with flecainide, 150 mg twice daily, he had an episode of sustained ventricular tachycardia, also at his peak exercise level. Patient 3 had paroxysmal atrial fibrillation and hypertrophic cardiomyopathy but no previous ventricular arrhythmia. She died suddenly within 10 days of starting flecainide therapy. Judged from previous findings none of these patients was considered at high risk for proarrhythmia. These cases suggest a possible relation between vigorous exercise, atrial fibrillation, and the proarrhythmic properties of flecainide and indicate the limitations of classifying patients as "high-risk" or "low-risk" for proarrhythmic complications of anti-arrhythmic therapy.     

Atrioventricular nodal tachycardia occurring during atrial fibrillation

We describe the case of a 32-year-old woman with palpitations and atrial fibrillation (AF) as the only documented arrhythmia. The patient underwent electrophysiologic study and was found to have inducible AV nodal reentrant tachycardia (AVNRT). During a prolonged episode of AVNRT, AF developed in both atria, but AVNRT persisted. Dissociation of the atria during AVNRT is evidence that the atrium is not necessary in AVNRT. This case also illustrates the utility of an electrophysiologic study in locating a potentially curable arrhythmia as the primary cause of AF in young patients.