The incidence of atrial fibrillation (AF) and congestive heart failure is rising rapidly in the U.S., because the population is growing older. The birth rate in the U.S. is declining, making the average age rise. The most devastating complication of AF is cerebral artery embolism (blood clot) with resultant stroke. Severe disability often results in this setting. Anticoagulation therapy has been shown to markedly reduce the incidence of stroke from AF, and direct oral anticoagulants (DOACs), some of which have been approved only recently, have replaced warfarin (Coumadin) as the drug of choice for stroke prevention in AF. DOACs are as effective or more effective than warfarin in this setting and bleeding events are significantly less likely as compared to warfarin. Commonly used DOACs include dabigatran (Pradaxa), rivaroxaban (Xarelto), apixaban (Eliquis), and edoxaban (Savaysa). Platelet inhibitors like aspirin are not effective at stroke prevention in AF.
Late last year, the American Heart Association/American College of Cardiology published new guidelines and recommendations for the treatment of AF as it pertains to stroke prevention. The updated guidelines reinforced the use of the CHA2DS2-VASc tool to assess stroke risk. A CHA2DS2-VASc score is calculated as follows: the presence of or history of Congestive heart failure – 1 point; Hypertension – 1 point; Age 75 or older – 2 points; Diabetes – 1 point; Stroke or TIA – 2 points; Vascular disease (i.e. heart attack or peripheral arterial disease) – 1 point; Age 65-74 – 1 point; Sex female – 1 point. Anticoagulation is strongly recommended for AF stroke prevention in men with a score of 2 or more, and in women with a score of 3 or more. In men with a score of 1 and women with a score of 2, shared decision making with the treating physician regarding anticoagulation should occur. Men with a score of 0 and women with a score of 1 do not need anticoagulation. Patients with mitral stenosis and prosthetic mechanical heart valves should be given warfarin, not a DOAC. A recent trial that compared dabigatran to warfarin for stroke prevention in patients with mechanical heart valves had to be discontinued early because of the presence of blood clots on the mechanical heart valves in the dabigatran group.
In general, DOACs are not recommended for those with severe kidney disease or on dialysis. At present, warfarin is recommended for these patients. Anticoagulation therapy is indicated for AF irrespective of whether the AF is paroxysmal, persistent, or permanent. Patients with atrial flutter should be handled in a manner similar to those with AF. In patients over 80, the lowest DOAC dose should be used to minimize the risk of bleeding, although many patients in this category refuse anticoagulation because, if a stroke occurs while on a DOAC, it is more likely to be hemorrhagic, which usually results in more severe consequences. Lastly, there is no solid scientific evidence that one DOAC is more effective or safer than any of the others. On a practical note, all the DOACs available at present are still on patent, which means they are brand-named and no generics yet exist making them expensive and often not covered by health plans. If you or someone you know has AF and is not on a DOAC, get to your doctor to have your risk of stroke assessed.
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By Peter Galvin, MDBLOG COMMENTS POWERED BY DISQUS