Ulrich Schotten

2012 focused update of the ESC Guidelines for the management of atrial fibrillation

ACCF : American College of Cardiology Foundation ACCP : American College of Chest Physicians ACS : acute coronary syndrome ACT : Atrial arrhythmia Conversion Trial ADONIS : American–Australian–African trial with DronedarONe In atrial fibrillation or flutter for the maintenance of Sinus rhythm AF : atrial fibrillation AHA : American Heart Association ANDROMEDA : ANtiarrhythmic trial with DROnedarone in Moderate-to-severe congestive heart failure Evaluating morbidity DecreAse APHRS : Asia Pacific Heart Rhythm Society aPTT : activated partial thromboplastin time ARB : angiotensin-receptor blocker ARISTOTLE : Apixaban for Reduction In STroke and Other ThromboemboLic Events in atrial fibrillation ATHENA : A placebo-controlled, double-blind, parallel arm Trial to assess the efficacy of dronedarone 400 mg b.i.d. for the prevention of cardiovascular Hospitalization or death from any cause in patiENts with Atrial fibrillation/atrial flutter ATRIA : AnTicoagulation and Risk factors In Atrial fibrillation AVERROES : Apixaban VErsus acetylsalicylic acid (ASA) to Reduce the Rate Of Embolic Stroke in atrial fibrillation patients who have failed or are unsuitable for vitamin K antagonist treatment AVRO : A prospective, randomized, double-blind, Active-controlled, superiority study of Vernakalant vs. amiodarone in Recent Onset atrial fibrillation b.i.d : bis in die (twice daily) b.p.m. : beats per minute CABANA : Catheter ABlation vs . ANtiarrhythmic drug therapy for Atrial fibrillation CABG : coronary artery bypass graft CAP : Continued Access to Protect AF CHA2DS2-VASc : Congestive heart failure or left ventricular dysfunction Hypertension, Age ≥75 (doubled), Diabetes, Stroke (doubled)-Vascular disease, Age 65–74, Sex category (female) CHADS2 : Congestive heart failure, Hypertension, Age ≥75, Diabetes, Stroke (doubled) CI : confidence interval CRAFT : Controlled Randomized Atrial Fibrillation Trial CrCl : creatinine clearance DAFNE : Dronedarone Atrial FibrillatioN study after Electrical cardioversion DIONYSOS : Randomized Double blind trIal to evaluate efficacy and safety of drOnedarone (400 mg b.i.d.) vs . amiodaroNe (600 mg q.d. for 28 daYS, then 200 mg qd thereafter) for at least 6 mOnths for the maintenance of Sinus rhythm in patients with atrial fibrillation EAST : Early treatment of Atrial fibrillation for Stroke prevention Trial EHRA : European Heart Rhythm Association ECG : electrocardiogram EMA : European Medicines Agency ERATO : Efficacy and safety of dRonedArone for The cOntrol of ventricular rate during atrial fibrillation EURIDIS : EURopean trial In atrial fibrillation or flutter patients receiving Dronedarone for the maIntenance of Sinus rhythm FAST : atrial Fibrillation catheter Ablation vs . Surgical ablation Treatment FDA : Food and Drug Administration Flec-SL : Flecainide Short-Long trial HAS-BLED : Hypertension, Abnormal renal/liver function, Stroke, Bleeding history or predisposition, Labile INR, Elderly, Drugs/alcohol concomitantly HF-PEF : heart failure with preserved ejection fraction HF-REF : heart failure with reduced ejection fraction HR : hazard ratio HRS : Heart Rhythm Society ICH : intracranial haemorrhage INR : international normalized ratio i.v. : intravenous J-RHYTHM : Japanese RHYTHM management trial for atrial fibrillation LAA : left atrial appendage LoE : level of evidence LVEF : left ventricular ejection fraction MANTRA-PAF : Medical ANtiarrhythmic Treatment or Radiofrequency Ablation in Paroxysmal Atrial Fibrillation NICE : National Institute for Health and Clinical Excellence NOAC : novel oral anticoagulant NSAID : non-steroidal anti-inflammatory drug NYHA : New York Heart Association OAC : oral anticoagulant or oral anticoagulation o.d. : omni die (every day) PALLAS : Permanent Atrial fibriLLAtion outcome Study using dronedarone on top of standard therapy PCI : percutaneous coronary intervention PREVAIL : Prospective Randomized EVAluation of the LAA closure device In patients with atrial fibrillation v s. Long-term warfarin therapy PROTECT AF : WATCHMAN LAA system for embolic PROTECTion in patients with Atrial Fibrillation PT : prothrombin time RAAFT : Radio frequency Ablation Atrial Fibrillation Trial RE-LY : Randomized Evaluation of Long-term anticoagulant therapY with dabigatran etexilate ROCKET-AF : Rivaroxaban Once daily oral direct factor Xa inhibition Compared with vitamin K antagonism for prevention of stroke and Embolism Trial in atrial fibrillation RRR : relative risk reduction TE : thromboembolism TIA : transient ischaemic attack t.i.d. : ter in die (three times daily) TOE : transoesophageal echocardiogram TTR : time in therapeutic range VKA : vitamin K antagonist Guidelines summarize and evaluate all currently available evidence on a particular issue with the aim of assisting physicians in selecting the best management strategy for an individual patient suffering from a given condition, taking into account the impact on …

Electropathological Substrate of Long-Standing Persistent Atrial Fibrillation in Patients With Structural Heart Disease Longitudinal Dissociation

Background—The electropathological substrate of persistent atrial fibrillation (AF) in humans is largely unknown. The aim of this study was to compare the spatiotemporal characteristics of the fibrillatory process in patients with normal sinus rhythm and long-standing persistent AF. Methods and Results—During cardiac surgery, epicardial mapping (244 electrodes) of the right atrium (RA), the left lateral wall (LA), and the posterior left atrium (PV) was performed in 24 patients with long-standing persistent AF. Twenty-five patients with normal sinus rhythm, in whom AF was induced by rapid pacing, served as a reference group. A mapping algorithm was developed that separated the complex fibrillation process into its individual elements (wave mapping). Parameters used to characterize the substrate of AF were (1) the total length of interwave conduction block, (2) the number of fibrillation waves, and (3) the ratio of block to collision of fibrillation waves (dissociation index). In 4403 maps of persistent AF, no evidence for the presence of stable foci or rotors was found. Instead, many narrow wavelets propagated simultaneously through the atrial wall. The lateral boundaries of these waves were formed by lines of interwave conduction block, predominantly oriented parallel to the atrial musculature. Lines of block were not fixed but continuously changed on a beat-to-beat basis. In patients with persistent AF, the total length of block in the RA was more than 6-fold higher than during acute AF (median, 21.1 versus 3.4 mm/cm2; P<0.0001). The highest degree of interwave conduction block was found in the PV area (33.0 mm/cm2). The number of fibrillation waves during persistent AF was 4.5/cm2 compared with 2.3 during acute AF, and the dissociation index was 7.3 versus 1.5 (P<0.0001). The interindividual variation of these parameters among patients was high. Conclusions—Electric dissociation of neighboring atrial muscle bundles is a key element in the development of the substrate of human AF. The degree of the pathological changes can be measured on an individual basis by electrophysiological parameters in the spatial domain.

Cellular Mechanisms of Depressed Atrial Contractility in Patients With Chronic Atrial Fibrillation

Background —After cardioversion of atrial fibrillation (AF), the contractile function of the atria is temporarily impaired. Although this has significant clinical implications, the underlying cellular mechanisms are poorly understood. Methods and Results —Forty-nine consecutive patients submitted for mitral valve surgery were investigated. Twenty-three were in persistent AF (≥3 months); the others were in sinus rhythm. Before extracorporal circulation, the right atrial appendage was excised. &bgr;-Adrenoceptors were quantified by radioligand binding, and G proteins were quantified by Western blot analysis. The isometric contractile response to Ca2+, isoproterenol, Bay K8644, and the postrest potentiation of contractile force were investigated in thin atrial trabeculae, which were also examined histologically. The contractile force of the atrial preparations obtained from AF patients was 75% less than that in preparations from patients in sinus rhythm. Also, the positive inotropic effect of isoproterenol was impaired, and Bay K8644 failed to increase atrial contractile force. In contrast, the response to extracellular Ca2+ was maintained, and the postrest potentiation was preserved. &bgr;-Adrenoceptor density and G-protein expression were unchanged. Histological examination revealed 14% more myolysis in the atria of AF patients. Conclusions —After prolonged AF, atrial contractility was reduced by 75%. The impairment of &bgr;-adrenergic modulation of contractile force cannot be explained by downregulation of &bgr;-adrenoceptors or changes in G proteins. Dysfunction of the sarcoplasmic reticulum does not occur after prolonged AF. Failure of Bay K8644 to restore contractility suggests that the L-type Ca2+ channel is responsible for the contractile dysfunction. The restoration of contractile force by high extracellular Ca2+ shows that the contractile apparatus itself is nearly completely preserved after prolonged AF.

Electropathological Substrate of Longstanding Persistent Atrial Fibrillation in Patients With Structural Heart Disease Epicardial Breakthrough

Background— During persistent atrial fibrillation (AF), waves with a focal spread of activation are frequently observed. The origin of these waves and their relevance for the persistence of AF are unknown. Methods and Results— In 24 patients with longstanding persistent AF and structural heart disease, high-density mapping of the right and left atria was performed during cardiac surgery. In a reference group of 25 patients, AF was induced by rapid pacing. For data analysis, a mapping algorithm was developed that separated the fibrillatory process into its individual wavelets and identified waves with a focal origin. During persistent AF, the incidence of focal fibrillation waves in the right atrium was almost 4-fold higher than during acute AF (median, 0.46 versus 0.12 per cycle per 1 cm2 (25th to 75th percentile, 0.40 to 0.77 and 0.01 to 0.27; P<0.0001). They were widely distributed over both atria and were recorded at 46±18% of all electrodes. A large majority (90.5%) occurred as single events. Repetitive focal activity (>3) happened in only 0.8%. The coupling interval was not more than 11 ms shorter than the average AF cycle length (P=0.04), and they were not preceded by a long interval. Unipolar electrograms at the site of origin showed small but clear R waves. These data favor epicardial breakthrough rather than a cellular focal mechanism as the underlying mechanism. Often, conduction from a site of epicardial breakthrough was blocked in 1 or more directions. This generated separate multiple wave fronts propagating in different directions over the epicardium. Conclusions— Focal fibrillation waves are due to epicardial breakthrough of waves propagating in deeper layers of the atrial wall. In patients with longstanding AF, the frequency of epicardial breakthroughs was 4 times higher than during acute AF. Because they provide a constant source of independent fibrillation waves originating over the entire epicardial surface, they offer an adequate explanation for the high persistence of AF in patients with structural heart disease.

PITX2c Is Expressed in the Adult Left Atrium, and Reducing Pitx2c Expression Promotes Atrial Fibrillation Inducibility and Complex Changes in Gene Expression

Background—Intergenic variations on chromosome 4q25, close to the PITX2 transcription factor gene, are associated with atrial fibrillation (AF). We therefore tested whether adult hearts express PITX2 and whether variation in expression affects cardiac function. Methods and Results—mRNA for PITX2 isoform c was expressed in left atria of human and mouse, with levels in right atrium and left and right ventricles being 100-fold lower. In mice heterozygous for Pitx2c (Pitx2c+/−), left atrial Pitx2c expression was 60% of wild-type and cardiac morphology and function were not altered, except for slightly elevated pulmonary flow velocity. Isolated Pitx2c+/− hearts were susceptible to AF during programmed stimulation. At short paced cycle lengths, atrial action potential durations were shorter in Pitx2c+/− than in wild-type. Perfusion with the &bgr;-receptor agonist orciprenaline abolished inducibility of AF and reduced the effect on action potential duration. Spontaneous heart rates, atrial conduction velocities, and activation patterns were not affected in Pitx2c+/− hearts, suggesting that action potential duration shortening caused wave length reduction and inducibility of AF. Expression array analyses comparing Pitx2c+/− with wild-type, for left atrial and right atrial tissue separately, identified genes related to calcium ion binding, gap and tight junctions, ion channels, and melanogenesis as being affected by the reduced expression of Pitx2c. Conclusions—These findings demonstrate a physiological role for PITX2 in the adult heart and support the hypothesis that dysregulation of PITX2 expression can be responsible for susceptibility to AF.

Comprehensive risk reduction in patients with atrial fibrillation: emerging diagnostic and therapeutic options-a report from the 3rd Atrial Fibrillation Competence NETwork/European Heart Rhythm Association consensus conference

While management of atrial fibrillation (AF) patients is improved by guideline-conform application of anticoagulant therapy, rate control, rhythm control, and therapy of accompanying heart disease, the morbidity and mortality associated with AF remain unacceptably high. This paper describes the proceedings of the 3rd Atrial Fibrillation NETwork (AFNET)/European Heart Rhythm Association (EHRA) consensus conference that convened over 60 scientists and representatives from industry to jointly discuss emerging therapeutic and diagnostic improvements to achieve better management of AF patients. The paper covers four chapters: (i) risk factors and risk markers for AF; (ii) pathophysiological classification of AF; (iii) relevance of monitored AF duration for AF-related outcomes; and (iv) perspectives and needs for implementing better antithrombotic therapy. Relevant published literature for each section is covered, and suggestions for the improvement of management in each area are put forward. Combined, the propositions formulate a perspective to implement comprehensive management in AF.

Renal Sympathetic Denervation Suppresses Postapneic Blood Pressure Rises and Atrial Fibrillation in a Model for Sleep Apnea

The aim of this study was to identify the relative impact of adrenergic and cholinergic activity on atrial fibrillation (AF) inducibility and blood pressure (BP) in a model for obstructive sleep apnea. Obstructive sleep apnea is associated with sympathovagal disbalance, AF, and postapneic BP rises. Renal denervation (RDN) reduces renal efferent and possibly also afferent sympathetic activity and BP in resistant hypertension. The effects of RDN compared with &bgr;-blockade by atenolol on atrial electrophysiological changes, AF inducibility, and BP during obstructive events and on shortening of atrial effective refractory period (AERP) induced by high-frequency stimulation of ganglionated plexi were investigated in 20 anesthetized pigs. Tracheal occlusion with applied negative tracheal pressure (NTP; at −80 mbar) induced pronounced AERP shortening and increased AF inducibility in all of the pigs. RDN but not atenolol reduced NTP-induced AF-inducibility (20% versus 100% at baseline; P=0.0001) and attenuated NTP-induced AERP shortening more than atenolol (27±5 versus 43±3 ms after atenolol; P=0.0272). Administration of atropine after RDN or atenolol completely inhibited NTP-induced AERP shortening. AERP shortening induced by high-frequency stimulation of ganglionated plexi was not influenced by RDN, suggesting that changes in sensitivity of ganglionated plexi do not play a role in the antiarrhythmic effect of RDN. Postapneic BP rise was inhibited by RDN and not modified by atenolol. We showed that vagally mediated NTP-induced AERP shortening is modulated by RDN or atenolol, which emphasizes the importance of autonomic disbalance in obstructive sleep apnea-associated AF. Renal denervation displays antiarrhythmic effects by reducing NTP-induced AERP shortening and inhibits postapneic BP rises associated with obstructive events.

Post-operative atrial fibrillation: a maze of mechanisms

Post-operative atrial fibrillation (POAF) is one of the most frequent complications of cardiac surgery and an important predictor of patient morbidity as well as of prolonged hospitalization. It significantly increases costs for hospitalization. Insights into the pathophysiological factors causing POAF have been provided by both experimental and clinical investigations and show that POAF is ‘multi-factorial’. Facilitating factors in the mechanism of the arrhythmia can be classified as acute factors caused by the surgical intervention and chronic factors related to structural heart disease and ageing of the heart. Furthermore, some proarrhythmic mechanisms specifically occur in the setting of POAF. For example, inflammation and beta-adrenergic activation have been shown to play a prominent role in POAF, while these mechanisms are less important in non-surgical AF. More recently, it has been shown that atrial fibrosis and the presence of an electrophysiological substrate capable of maintaining AF also promote the arrhythmia, indicating that POAF has some proarrhythmic mechanisms in common with other forms of AF. The clinical setting of POAF offers numerous opportunities to study its mechanisms. During cardiac surgery, biopsies can be taken and detailed electrophysiological measurements can be performed. Furthermore, the specific time course of POAF, with the delayed onset and the transient character of the arrhythmia, also provides important insight into its mechanisms. This review discusses the mechanistic interaction between predisposing factors and the electrophysiological mechanisms resulting in POAF and their therapeutic implications.

Electrical and Contractile Remodeling During the First Days of Atrial Fibrillation Go Hand in Hand

Background—The mechanisms of the atrial contractile dysfunction induced by atrial fibrillation (AF) are not completely understood. In particular, the relation between the atrial dysfunction and electrical remodeling has not yet been studied. Methods and Results—Seven goats were chronically instrumented with electrodes sutured to the atria and with ultrasonic piezoelectric crystals to record the atrial diameters. A pressure transducer was implanted in the right atrium. After 5 minutes, 3 hours, and throughout the first 5 days of artificially maintained AF, atrial contractile function was measured and the atrial effective refractory period (AERP) was monitored for comparison. Also, the positive inotropic effects of the L-type Ca2+-channel agonist BayY5959 and short trains of rapid atrial pacing were studied. After resumption of sinus rhythm, the recovery of atrial contractile function was followed. After 5 minutes of AF, atrial contractility was decreased by ≈55% but recovered completely within 10 minutes. Five days of AF nearly completely abolished the atrial contractile function, and recovery took 2 days. During the first days of AF, the development of the contractile dysfunction followed the same time course as the shortening of AERP (electrical remodeling). In remodeled atria, BayY5959 increased atrial contractility to the same extent as it prolonged AERP. The inotropic effect of short trains of rapid atrial pacing was similar in normal and remodeled atria. Conclusions—Depending on the duration of AF, different mechanisms contribute to the AF-induced atrial hypocontractility. Atrial contractile remodeling during several days of AF goes hand in hand with electrical remodeling and might be caused by a reduction of the L-type Ca2+-current.

Atrial fibrillation-induced atrial contractile dysfunction: a tachycardiomyopathy of a different sort

OBJECTIVE Although AF-induced atrial contractile dysfunction has significant clinical implications the underlying intracellular mechanisms are poorly understood. METHODS From the right atrial appendages of 59 consecutive patients undergoing mitral valve surgery (31 in SR, 28 in chronic AF) thin muscle preparations (diameter<0.7 mm) were isolated. Isometric force of contraction was measured in the presence of different concentrations of Ca(2+) and isoprenaline. To assess the function of the sarcoplasmic reticulum, the force-frequency relationship and the post-rest potentiation were studied. The myocardial density of the ryanodine-sensitive calcium release channel (CRC) of the sarcoplasmic reticulum was determined by [3H]ryanodine binding. Myocardial content of SR-Ca(2+)-ATPase (SERCA), phospholamban (Plb), calsequestrin (Cals) and the Na(+)/Ca(2+)-exchanger (NCX) were analyzed by Western blot analysis. Adenylyl cyclase activity was measured with a radiolabeled bioassay using [32P]ATP as a tracer. RESULTS In 72 muscle preparations of SR patients contractile force was 10.9+/-1.8 mN/mm(2) compared to 3.3+/-0.9 mN/mm(2) (n=48, P<0.01) in AF patients. The positive inotropic effect of isoprenaline was diminished but the stimulatory effect on relaxation and the adenylyl cyclase were not altered in AF patients. The force-frequency relation and the post-rest potentiation were enhanced in atrial myocardium of AF patients. The protein levels of CRC, SERCA, Plb, and Cals were not different between the two groups. In contrast, the Na(+)/Ca(2+)-exchanger was upregulated by 67% in atria of AF patients. CONCLUSIONS AF-induced atrial contractile dysfunction is not due to beta-adrenergic desensitization or dysfunction of the sarcoplasmic reticulum and thus is based on different cellular mechanisms than a ventricular tachycardia-induced cardiomyopathy. Instead, downregulation or altered function of the L-type Ca(2+)-channel and an increased Ca(2+) extrusion via the Na(+)/Ca(2+)-exchanger seem to be responsible for the depressed contractility in remodeled atria.