New Treatment Guidelines: Atrial Fibrillation
By Gina D. Moore, PharmD, MBA
In March 2014, new treatment guidelines for the management of atrial fibrillation were published by an expert panel from the American College of Cardiology, American Heart Association and Heart Rhythm Society in collaboration with the Society of Thoracic Surgery1. The new guidelines are evidence-based and include both consensus recommendations and relevant data published on the topic to date. These guidelines supersede the consensus guidelines last published in 2006.
Atrial fibrillation (AF) may be classified as paroxysmal, persistent or permanent based on the duration of episodes. Nonvalvular AF is defined as AF in the absence of mitral valve stenosis, mechanical heart valve, or mitral valve repair. AF is generally attributed to structural and/or electrophysiologic abnormalities that result in abnormal impulse formation and/or propagation. The most serious complication associated with AF is stroke; treatment decisions are based on the assessing the patient’s risk of stroke and identifying those at low, moderate and high risk for stroke. Other patient factors, such as hypertension and obesity, may further predispose patients to stroke and should also be addressed.
Risk stratification is based on the patient’s CHADS2 or CHA2DS2-VASc score. CHADS2 is an acronym for Congestive Heart Failure, Hypertension, Age ≥ 75 years, Diabetes mellitus, and Stroke. The “VASc” component further includes Vascular disease, Age 65-74 years, and Sex category. Points are assigned based on the presence of those factors. Patients with a CHA2DS2-VASc score of 2 or greater, or patients with a history of stroke or transient ischemic attack (TIA) are at higher risk and should be treated with oral anticoagulants. As opposed to previous recommendations where only warfarin was recommended, the current guidelines also include newer drugs such as dabigatran, rivaroxaban, and apixaban as potential options.
For patients with mechanical heart valves, warfarin is still recommended as the sole option. For all patients that receive warfarin, the INR should be determined at least weekly when therapy is initiated and monthly once stable. The goal INR range is 2.0 to 3.0. Renal function should be monitored at least yearly for patients receiving dabigatran, rivaroxaban, and apixaban. In patients with end-stage renal disease and patients on dialysis, dabigatran, rivaroxaban, and apixaban are not recommended. The choice of antithrombotic agent should individualized based on shared decision making between the patient and his or her provider. The patient should be knowledgeable on the risks of both stroke and bleeding, and should be made aware of the monitoring required with each therapy. The agent(s) available through the patient’s prescription benefit may also play a role in the therapy decision.
Another significant change with the new guidelines is recommendations for aspirin use. In previous guidelines, aspirin was recommended in patients with low cardiovascular risk. With the 2014 guidelines, the aspirin treatment recommendation was removed due to lack of data that attributed a decreased stroke risk with aspirin use.
As with previous guidelines, control of the ventricular rate is recommended for patients with paroxysmal, persistent or permanent AF. Recommended therapies for rate control are a beta blocker or nondiphydropyridine calcium channel antagonist. Choices for oral beta blocker therapy include metoprolol, atenolol, propranolol, nadolol, carvedilol, and bisoprolol. The two nondihydropyridine calcium channel antagonists include verapamil and diltiazem. Guidelines suggest a target resting heart rate of less than 80 beats per minute (bpm) as reasonable for symptomatic management of AF. For patients that experience AF-related symptoms during activity, pharmacologic therapy should be adjusted as necessary.
Although antiarrhythmic agents are still mentioned in the guidelines, treatment of the precipitating or reversible causes of AF are first recommended. Antiarrhythmic drug options include amiodarone, dofetilide, dronedarone, flecainide, propafenone, and sotalol. The risk of proarrhythmia is present with antiarrhythmic agents, and clinicians are cautioned to assess risk versus benefit before starting any of the agents. Although amiodarone is included as an option, because of its potential toxicities, it is suggested only when other options have failed or are contraindicated.
1January CT, Wann LS, Alpert JS, Calkins H, Cleveland Jr JC, Cigarroa JE, Conti JB, Elllinor PT, Ezekowitz MD, Field ME, Murray KT, Sacco RL, Stevenson WG, Tchou PJ, Tracy CM, Yancy CW, 2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation: Executive Summary, Journal of the American College of Cardiology (2014), doi: 10.1016/j.jacc.2014.03.021.
A version of this article was previously published on our sister site, PharmacyChoice.com.
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Gina Moore is Director of Clinical Affairs and Assistant Professor in the Department of Clinical Pharmacy at the University of Colorado Skaggs School of Pharmacy and Pharmaceutical Science. She is responsible for numerous projects and entrepreneurial partnerships with the university. Moore is also a speaker at RxSchool.com where she presents live webinar courses and contributes to the site’s CE curriculum.