Introduction 2/9/2015

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1 Thomas Haffey, D.O. FACC, FACOI, FNLA, CSOM February, 2015 Atrial Tachycardias Diagram summarizing types of atrial tachycardias often encountered in patients with a history of AF, including those seen after catheter or surgical ablation procedures. P-wave morphologies are shown for common types of atrial flutter; however, the P-wave morphology is not always a reliable guide to the reentry circuit location or the distinction between common atrial flutter and other macroreentrant atrial tachycardias. *Exceptions to P-wave morphology and rate are common in scarred atria. AF indicates atrial fibrillation; bpm, beats per minute; and ECG, electrocardiogram (72,80). Introduction Atrial Fibrillation (AF) is the most common sustained arrhythmia. The incidence and prevalence of AF is increasing. Lifetime risk over the age of 40 years is ~25%. 1

2 Introduction Complications of AF include hemodynamic instability, cardiomyopathy, cardiac failure, and embolic events such as stroke. Characterized by disorganized atrial electrical activity and contraction. Mechanism of Atrial Fibrillation The mechanisms underlying AF are not fully understood but it requires an initiating event (focal atrial activity / PACs) and substrate for maintenance (i.e. dilated left atrium). Mechanism of Atrial Fibrillation Focal activation In which AF originates from an area of focal activity. This activity may be triggered, due to increased automaticity, or from micro re entry. Often located in the pulmonary veins. Multiple wavelet mechanism In which multiple small wandering wavelets are formed. The fibrillation is maintained by re entry circuits formed by some of the wavelets. This process is potentiated in the presence of a dilated LA the larger surface area facilitates continuous waveform propagation. 2

3 Causes of Atrial Fibrillation Ischemic heart disease Hypertension Valvular heart disease (esp. mitral stenosis / regurgitation) Acute infections Electrolyte disturbance (hypokalaemia, hypomagnesaemia) Thyrotoxicosis Drugs (e.g. sympathomimetics) Pulmonary embolus Pericardial disease Acid base disturbance Pre excitation syndromes Cardiomyopathies: dilated, hypertrophic. Pheochromocytoma ECG Features Irregularly irregular rhythm. No P waves. Absence of an isoelectric baseline. Variable ventricular rate. QRS complexes usually < 120 msec unless pre existing bundle branch block, accessory pathway, or rate related aberrant conduction. Fibrillatory waves may be present and can be either fine (amplitude < 0.5mm) or coarse (amplitude >0.5mm). Fibrillatory waves may mimic P waves leading to misdiagnosis. Other features: Ashman s Phenomenon presences of aberrantly conducted beats, usually of RBBB morphology, due a long refractory period as determined by the preceding R R interval. The ventricular response and thus ventricular rate in AF is dependent on several factors including vagal tone, other pacemaker foci, AV node function, refractory period, and medications. 3

4 Variations Commonly AF is associated with a ventricular rate ~ AF is often described as having rapid ventricular response once the ventricular rate is > 100 bpm. Variations Slow AF is a term often used to describe AF with a ventricular rate < 60 bpm. Causes of slow AF include hypothermia, digoxin toxicity, medications, and sinus node dysfunction. Classification First episode initial detection of AF regardless of symptoms or duration Recurrent AF More than 2 episodes of AF Paroxysmal AF Self terminating episode < 7 days Persistent AF Not self terminating, duration > 7 days Long standing persistent AF > 1 year Permanent (Accepted) AF Duration > 1 year in which rhythm control interventions are not pursued or are unsuccessful 4

5 Classification of Atrial Fibrillation Note paroxysmal AF of > 48 hours duration is unlikely to spontaneously revert to sinus rhythm and anticoagulation must be consider Management of Atrial Fibrillation Management of atrial fibrillation is complex depending on duration of atrial fibrillation, co morbidities, underlying cause, symptoms, and age Management of atrial fibrillation Diagnosis of atrial fibrillation. Assessment of duration. Assessment for anticoagulation. Rate or rhythm control. Treatment of underlying / associated diseases. 5

6 Risk of Stroke and Anticoagulation Atrial fibrillation is associated with disorganized atrial contraction and stasis within the left atrial appendage with associated thrombus formation and risk of embolic stroke. AF associated with valvular disease has a particularly high risk of stroke. Guideline recommendations for stroke prevention and anticoagulation also include atrial flutter due to the high likelihood of these patients developing AF. Risk of Stroke and Anticoagulation Anticoagulation strategies may include warfarin, aspirin, clopidogrel and newer agents such as dabigatran. Anticoagulation guidelines are based on risk of stroke vs. risk of bleeding. Stroke risk stratification requires either an assessment of risk factors or application of a risk score e.g. CHADS 2 or CHA 2 DS 2 VASc. Risk of bleeding can be estimated by the HAS BLED score New oral Anticoagulants Update 6

7 NOA agents Vitamin k antagonists Factor Xa inhibitors Factor IIa (thrombin) NOA Dabigatran (Pradaxa) Rivaroxaban (Xarelto) Apixaban (Eliquis) Atrial Fibrillation in WPW Atrial fibrillation can occur in up to 20% of patients with WPW The accessory pathway allows for rapid conduction directly to the ventricles bypassing the AV node Rapid ventricular rates may result in degeneration to VT or VF 7

8 ECG features Atrial Fibrillation in WPW Rate > 200 bpm Irregular rhythm Wide QRS complexes due to abnormal ventricular depolarization via accessory pathway QRS Complexes change in shape and morphology Axis remains stable unlike Polymorphic VT Treatment Treatment with AV nodal blocking drugs e.g. adenosine, calcium channel blockers, beta blockers may increase conduction via the accessory pathway with a resultant increase in ventricular rate and possible degeneration into VT or VF Treatment In a hemodynamically unstable patient urgent synchronized DC cardioversion is required. Medical treatment options in a stable patient include procainamide or ibutilide, although DC cardioversion may be preferred. 8

9 Antithrombotic Therapy to Prevent Stroke in Patients Who Have Nonvalvular AF (Meta-Analysis) ACTIVE-W indicates Atrial Fibrillation Clopidogrel Trial With Irbesartan for Prevention of Vascular Events-W; AF, atrial fibrillation; AFASAK, Atrial Fibrillation, Aspirin and Anticoagulant Therapy Study; ATAFS, Antithrombotic Therapy in Atrial Fibrillation Study; BAATAF, Boston Area Anticoagulation Trial for Atrial Fibrillation; CAFA, Canadian Atrial Fibrillation Anticoagulation; CI, confidence interval; EAFT, European Atrial Fibrillation Trial; ESPS, European Stroke Prevention Study; JAST, Japan AF Stroke Prevention Trial; LASAF, Low-Dose Aspirin, Stroke, Atrial Fibrillation; NASPEAF, National Study for Prevention of Embolism in Atrial Fibrillation; PATAF, Primary Prevention of Arterial Thromboembolism in Nonrheumatic Atrial Fibrillation; SAFT, Swedish Atrial Fibrillation Trial; SIFA, Studio Italiano Fibrillazione Atriale; SPAF, Stroke Prevention in Atrial Fibrillation Study; SPINAF, Stroke Prevention in Atrial Fibrillation; and UK-TIA, United Kingdom Transient Ischemic Attack. 2/9/2015 Mechanisms of AF AF indicates atrial fibrillation; Ca ++, ionized calcium; and RAAS, renin-angiotensin-aldosterone system. Coagulation Cascade AT indicates antithrombin and VKAs, vitamin K antagonists. 9

10 Pooled Estimates of Stroke or Systemic Embolism in Patients With AF Treated With Warfarin ACTIVE W indicates Atrial Fibrillation Clopidogrel Trial With Irbesartan for Prevention of Vascular Events-W; AF, atrial fibrillation; Amadeus, Evaluating the Use of SR34006 Compared to Warfarin or Acenocoumarol in Patients With Atrial Fibrillation; ARISTOTLE, Apixaban Versus Warfarin in Patients With AF; BAFTA, Birmingham Atrial Fibrillation Treatment of the Aged Study; CI, confidence interval; RE-LY, Randomized Evaluation of Long-Term Anticoagulation Therapy; ROCKET AF, Rivaroxaban Versus Warfarin in Nonvalvular Atrial Fibrillation; and SPORTIF, Stroke Prevention Using Oral Thrombin Inhibitor in Atrial Fibrillation. Approach to Selecting Drug Therapy for Ventricular Rate Control *Drugs are listed alphabetically. Beta blockers should be instituted following stabilization of patients with decompensated HF. The choice of beta blocker (e.g., cardioselective) depends on the patient s clinical condition. Digoxin is not usually first-line therapy. It may be combined with a beta blocker and/or a nondihydropyridine calcium channel blocker when ventricular rate control is insufficient and may be useful in patients with HF. In part because of concern over its side-effect profile, use of amiodarone for chronic control of ventricular rate should be reserved for patients who do not respond to or are intolerant of beta blockers or nondihydropyridine calcium antagonists. COPD indicates chronic obstructive pulmonary disease; CV, cardiovascular; HF, heart failure; HFpEF, heart failure with preserved ejection fraction; and LV, left ventricular. Strategies for Rhythm Control in Patients With Paroxysmal* and Persistent AF *Catheter ablation is only recommended as first-line therapy for patients with paroxysmal AF (Class IIa recommendation). Drugs are listed alphabetically. Depending on patient preference when performed in experienced centers. Not recommended with severe LVH (wall thickness >1.5 cm). ǁShould be used with caution in patients at risk for torsades de pointes ventricular tachycardia. Should be combined with AV nodal blocking agents. AF indicates atrial fibrillation; AV, atrioventricular; CAD, coronary artery disease; HF, heart failure; and LVH, left ventricular hypertrophy. 10