Atrial fibrillation

Diagnosis

Routine office evaluation

A study of routine pulse checks or electrocardiograms during routine office visits, found that the annual rate of detection of atrial fibrillation in elderly patients improved from 1.04% to 1.63%. This implies that the sensitivity of the routine examination is 64% (1.04/1.63).

Electrocardiogram

Regarding the accuracy of the electrocardiogram:

• Interpreted by software:
  • sensitivity = 83%
  • specificity = 99%
• Interpreted by a primary care physician:
  • sensitivity = 80%
  • specificity = 92%
• Interpreted by a primary care physician with software:
  • sensitivity = 92%
  • specificity = 91%

Prognosis

Risk of stroke

The risk of stroke in a patient with atrial fibrillation can be predicted with the CHADS2 score.

Treatment

Clinical practice guidelines by the American College of Physicians and the American Academy of Family Physicians address treatment.

Rate control versus rhythm control

Medications

"Rate control with chronic anticoagulation is the recommended strategy for the majority of patients with atrial fibrillation. ... Rhythm control is appropriate when based on other special considerations, such as patient symptoms, exercise tolerance, and patient preference."

The goal rate is "80 beats per minute during resting ... and of less than 110 beats per minute during a 6-minute walk test."

As compared to rate control, rhythm control was associated with slight, although statistically insignificant, increase in adverse outcomes in randomized controlled trials. In addition, "the incidence of the components of the primary end point did not differ significantly according to whether the patient had sinus rhythm or atrial fibrillation at the end of follow-up." Whether the index episode was the initial or a recurrent episode did not effect results.

Randomized controlled trial of rhythm versus rate control

Study	Patients	Intervention in rhythm control group	Results
			Rhythm control group	Rate control group
Van Gelder 2002	All had prior episode of atrial dysrythmia requiring electrical cardioversion. All had current atrial dysrythmia for median of 32 days. 50% has previous heart failure.	Cardioversion followed by sotalol for median of 2.3 years. 86% to 99% received anticoagulation.	Sinus rhythm: 39% Cardiovascular death: 6.8% Thromboembolism: 5.5%	Sinus rhythm: 10% Cardiovascular death: 7% Thromboembolism: 7.9%
AFFIRM 2002	65% had prior episode of atrial dysrythmia. All had current atrial dysrythmia with 69% lasting 2 or more days. 23% has previous heart failure.	"antiarrhythmic drug used was chosen by the treating physician" for 5 years. 70% received anticoagulation.	Sinus rhythm: 63% Any death: 23.8% Ischemic stroke: 5.5%	Sinus rhythm: 35% Any death: 21.3% Ischemic stroke: 7.1%
Roy 2008	All had prior episode of atrial dysrythmia. 55% to 60% with current atrial dysrythmia. All with a history of heart failure and systolic dysfunction.	Amiodarone for median of 3 years. 90% received anticoagulation.	Sinus rhythm: 73% Cardiovascular death: 27% Any stroke: 3%	Sinus rhythm: 30% Cardiovascular death: 25% Any stroke: 4%

Episodic therapy

Episodic medical therapy has conflicting results with a positive uncontrolled before and after trial of flecainide and propafenone and a negative randomized controlled trial of episodic amiodarone versus continuous amiodarone.

Pulmonary-vein isolation

Randomized controlled trial have found that using ablation to cause pulmonary-vein isolation was superior to medical therapy and to atrioventricular-node ablation.

Anticoagulation

"Patients with atrial fibrillation should receive chronic anticoagulation with adjusted-dose warfarin, unless they are at low risk of stroke or have a specific contraindication to the use of warfarin (thrombocytopenia, recent trauma or surgery, alcoholism). "

Anticoagulation can prevent recurrent stroke. Among patients with nonvalvular atrial fibrillation, anticoagulation can reduce stroke by 60% while antiplatelet agents can reduce stroke by 20%. . However, a recent meta-analysis suggests harm from anti-coagulation started early after an embolic stroke.