Atrial fibrillation and congestive heart failure (CHF) are “growth industries” in 21st-century industrial nations. The rapid growth of the geriatric population in these countries plays an important role in the ever-increasing number of patients seen with these 2 clinical entities. Patients with atrial fibrillation are seen on a daily basis in both the clinic and the hospital. The most devastating complication resulting from atrial fibrillation is cerebral arterial embolism with resultant stroke. Severe disability often occurs in this setting. Anticoagulation therapy has been shown to reduce markedly the incidence of stroke in patients with atrial fibrillation, and fortunately, recently approved direct oral anticoagulants (DOACs) have rapidly replaced warfarin as the drugs of choice for stroke prevention in individuals with atrial fibrillation. The DOAC agents are as effective or more effective compared with warfarin for preventing arterial embolism, and bleeding events are significantly less likely with DOACs compared with warfarin.
Recently, the American Heart Association/American College of Cardiology (AHA/ACC) guideline committee published an update on previous atrial fibrillation guidelines with reinforced and new recommendations.1 Because patients with atrial fibrillation are so common in daily medical practice, this commentary will review the most important and most clinically relevant material from the recently updated atrial fibrillation guideline.
- 1.
The newly updated guideline reinforced the use of the CHA2DS2-VASc tool for stroke risk assessment in patients with atrial fibrillation.
A CHA2DS2-VASc score is calculated as follows: C = the presence of, or a history of, congestive heart failure – 1 point; H = hypertension – 1 point; A = age 75 or older – 2 points; D = diabetes – 1 point; S = stroke or transient ischemic attack – 2 points; V = the presence of vascular disease, for example a history of myocardial infarction, peripheral vascular disease, or atherosclerotic lesions documented by imaging – 1 point; A = ages 65-74 – 1 point; S = female sex – 1 point.
- 2.
Anticoagulant therapy is strongly recommended for atrial fibrillation related stroke prevention in men with a CHA2DS2-VASc score of 2 or more and in women with a score of 3 or more. In men with a score of 1 and in women with a score of 2, anticoagulation should be discussed with the patient and shared decision making should be exercised to decide if anticoagulation is to be initiated. Men with a score of 0 and women with a score of 1 do not need to be anticoagulated.
- 3.
DOACs are preferred to warfarin for stroke prevention in atrial fibrillation because there is less bleeding with these agents than with warfarin, and they are as effective or more effective compared with warfarin at preventing stroke in patients with atrial fibrillation. The DOACs include the following pharmaceutical agents: dabigatran, rivaroxaban, apixaban, and edoxaban.
- 4.
Patients with mitral stenosis and prosthetic mechanical heart valves should not receive a DOAC to prevent stroke. Warfarin should be prescribed. A recent clinical trial compared dabigatran with warfarin to prevent stroke in patients with a mechanical prosthetic valve.2 The trial was discontinued early because of presence of thrombus on the prosthetic valves of the patients who received dabigatran.
- 5.
In general, DOACs are not recommended at this time for patients with severe renal insufficiency or end-stage renal disease treated with dialysis. Information is lacking as to the doses of a DOAC needed for these patients. There is some data that supports the use of apixaban or edoxaban in patients with renal insufficiency, but warfarin is often preferred. It is probable that at some time in the future DOACs will be employed when dosage protocols have been firmly established for patients with atrial fibrillation and severe renal impairment.
- 6.
Anticoagulation therapy is indicated in patients with atrial fibrillation irrespective of whether the atrial fibrillation is paroxysmal, persistent, or permanent.
- 7.
Patients with atrial flutter should be handled in a manner similar to patients with atrial fibrillation. These patients are also at increased risk for arterial cerebral embolism.
In addition to these guideline recommendations, I have a few personal rules that I apply when considering anticoagulant therapy for stroke prevention in individuals with atrial fibrillation. In patients older than age 80, I usually prescribe the US Food and Drug Administration (FDA) approved lower dose of the DOACs. I do this to minimize the likelihood of bleeding in this high-risk population. In patients who are elderly and frail, I engage in shared decision making concerning the use of anticoagulants. Many of these patients choose to refuse anticoagulation because of the increased risk for hemorrhagic stroke. Unfortunately, platelet-blocking agents such as aspirin and clopidogrel have been shown to be substantially less effective at preventing stroke when compared with warfarin or DOAC anticoagulation in patients with atrial fibrillation. I therefore discourage patients with atrial fibrillation from using antiplatelet agents for this indication. Finally, I know of no solid scientific evidence implying that one DOAC is more effective or safer than another.
I encourage readers of The American Journal of Medicine to write to me if they agree or disagree with points made in my editorials. I can be reached at jalpert@shc.arizona.edu, or comment on our blog at amjmed.org.
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-Joseph S. Alpert, MDa,b,
This article originally appeared in the December 2019 issue of The American Journal of Medicine.
