Treatment Goals and Strategies
The treatment goals for a patient with atrial fibrillation are to control the ventricular response and prevent thromboembolic complications. The need for long-term anticoagulation to reduce the risk of stroke and TIA is based on the patient's risk level as measured by the CHADS (Cardiac failure, Hypertension, Age, Diabetes, Stroke Doubled) scoring system. Risk factors included in CHADS are HF, hypertension, age greater than 75 years, diabetes, and previous history of stroke or TIA. Patients with no CHADS risk factors are considered to be at low risk for thromboembolic events and should not receive anticoagulant therapy or aspirin monotherapy. Patients with a CHADS score of 1 or higher have a moderate-to-high risk of thromboembolism, and treatment with warfarin or one of the new anticoagulants, such as dabigatran, rivaroxaban, or apixaban, is recommended.
Strategies to control the ventricular response include rhythm control and rate control. The rate-control method allows the atria to continue to fibrillate, and pharmacotherapy (commonly, beta-blockers, nondihydropyridine calcium channel blockers, and digoxin) is used to control the ventricular rate. The rhythmcontrol strategy utilizes a pharmacologic or nonpharmacologic modality to restore the atria to normal sinus rhythm, after which pharmacologic therapy is used to maintain normal sinus rhythm.
While rhythm control offers the advantage of increased cardiac output due to preservation of synchronized atrial contraction, no studies have demonstrated a benefit in clinical outcomes versus rate control. The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) was a landmark randomized, multicenter trial of rate control versus rhythm control in 4,060 patients at high risk for stroke or death. AFFIRM found no significant difference between rhythm control and rate control in mortality incidence over 5 years (hazard ratio 1.15; 95% CI 0.99–1.34), but higher rates of hospitalization and adverse effects were seen in the rhythm-control group.
Although rhythm control with antiarrhythmic therapy does not confer a mortality benefit over rate control, it is a mainstay of therapy for atrial fibrillation patients, especially those who remain symptomatic despite adequate rate control. Antiarrhythmic agents are categorized according to the Vaughan Williams classification: class I, sodium channel blockers; class II, beta-blockers; class III, potassium channel blockers; and class IV, calcium channel blockers. This review will focus on the use of class IC and III agents for maintenance of normal sinus rhythm in patients with atrial fibrillation.
US Pharmacist. 2013;38(2):20-23. © 2013 Jobson Publishing