Author + information
- Hugh Calkins, MD∗ ()
- ↵∗Reprint requests and correspondence:
Dr. Hugh Calkins, Department of Cardiology, Johns Hopkins Hospital, Sheikh Zayed Tower 7125R, 1800 Orleans Street, Baltimore, Maryland 21287-0001.
Management of patients with atrial fibrillation (AF) can be considered a 3-legged stool. Physicians caring for AF patients must consider the issues of rate control, rhythm control, and stroke prevention and then make specific recommendations to their patients that address each of these issues.
Although each is important, it is well recognized that the single most important management decision in AF patients concerns the issue of stroke prevention. Strokes in patients with AF are often lethal or life altering. It is for this reason that much attention in the past decade has focused on creating scoring systems to assess stroke risk in AF patients, developing and demonstrating the efficacy of new anticoagulant drugs, and publishing guidelines that make recommendations regarding which AF patients require anticoagulation. In the recently updated American College of Cardiology/American Heart Association and Heart Rhythm Society (ACC/AHA/HRS) AF guidelines and the European Society of Cardiology AF guidelines, the more sensitive CHA2DS2-VASc (congestive heart failure, hypertension, age 75 years or older, diabetes mellitus, previous stroke or transient ischemic attack, vascular disease, age 65 to 74 years, female) risk stratification system has been recommended to assess stroke risk, replacing the older and less sensitive CHADS2 score (1,2). Both guidelines advise initiation of anticoagulation in patients with a CHA2DS2-VASc score of ≥2, and both guidelines advise that patients with a CHA2DS2-VASc score of 0 not be anticoagulated. The gray area in both guidelines concerns whether to anticoagulate patients with a CHA2DS2-VASc score of 1.
In this issue of the Journal, Chao et al. (3) report the stroke risk in AF patients with a single stroke risk factor irrespective of sex (because the scoring system considers female sex an independent risk factor). This was a retrospective study using data obtained from the National Health Insurance Research Database in Taiwan, which contains detailed health information on more than 23 million enrollees in this mandatory universal health insurance program. From this large database, 12,935 men and 7,900 women were identified who met the entry criteria for this study: a CHA2DS2-VASc score of 1 in men and 2 in women, with no use of anticoagulant or antiplatelet agents. The incidence of ischemic stroke was then determined. Of the 12,935 male AF patients, ischemic stroke occurred in 14.4% during 5.2 ± 4.3 years of follow-up. The annual stroke rate was 2.75%, ranging from 1.96% per year in patients with vascular disease to 3.5% per year for those 65 to 74 years of age. Of the 9,900 women with a CHA2DS2-VASc score of 2, ischemic stroke occurred in 14.9% during 5.2 ± 4.3 years of follow-up. The overall annual stroke rate was 2.55%, ranging from 1.91% per year in patients with hypertension to 3.34% per year for those 65 to 74 years of age. The authors conclude that not all stroke risk factors in the CHA2DS2-VASc risk score carry equal weight, with age between 65 and 74 years being the most important. They also propose that their data support anticoagulation in patients with a CHA2DS2-VASc score of 1 in men and 2 in women, especially for those 65 years of age or older.
The results of this study are striking and provide important new information supporting the practice of recommending anticoagulation for all AF patients except those at a very low stroke risk (as identified by a CHA2DS2-VASc score of 0 or 1 for women). It is remarkable that men and women with AF who had a CHA2DS2-VASc score of 1 (excluding sex) had annual stroke risks of 2.75% and 2.55%, respectively. This is markedly higher than the risk of intracranial hemorrhage (0.23% to 0.5%) reported in trials of the new oral anticoagulant drugs: dabigatran (4), rivaroxaban (5), apixaban (6), and edoxaban (7), referred to as non–vitamin K antagonist oral anticoagulant agents. For both groups, age was the most potent single risk factor, with an annual stroke risk for men and women between 65 and 74 years of age of 3.5% and 3.34%, respectively. Considering the safety and efficacy of antithrombotic therapy, it seems clear that we should think long and hard before recommending that patients with a CHA2DS2-VASc score of 1 not receive anticoagulant therapy.
Another issue concerns the recently published ACC/AHA/HRS AF management guidelines (2), which state that for AF patients with a CHA2DS2-VASc score of 1, “no antithrombotic therapy or treatment with an oral anticoagulant or aspirin may be considered (IIb).” The guidelines also emphasize that “in patients with AF, antithrombotic therapy should be individualized based on shared decision making after discussion of the absolute and RRs of stroke and bleeding, and the patient’s values and preferences” (Class I) (2). A somewhat stronger approach is used in the updated European Society of Cardiology guidelines, which state that in patients with a CHA2DS2-VASc score of 1, oral anticoagulant therapy should be considered after assessment of bleeding risk and patient preferences (Class IIa) (1).
In my mind, it is not time to update the ACC/AHA/HRS guidelines based on this single study. Although the data are important and inform this discussion, they are imperfect and not definitive. After all, this was a retrospective study in which diagnosis codes were used to try to tease out a population of patients with AF who had a CHA2DS2-VASc score of 1, were not receiving anticoagulant or antiplatelet therapy, and had experienced a thrombotic stroke. This was not a prospective, randomized clinical trial comparing 2 management strategies.
At the end of the day, as recommended by the ACC/AHA/HRS 2014 guidelines for managing patients with AF, “antithrombotic therapy should be individualized based on shared decision making after discussion of the absolute and RRs (relative risks) of stroke and bleeding, and the patient’s values and preferences (Class I).” Experienced clinicians recognize that there are many nuances to predicting stroke risk. For example, hypertension is not a “yes or no” variable. A patient with a single documented blood pressure reading over the ideal range is quite different from a patient with uncontrolled hypertension. Similarly, a patient who has been in AF for 5 years continuously and has a left atrial size of 5.5 cm is at far higher stroke risk than a patient with AF and normal left atrial size who experiences 5 min of AF per year. There are many other factors that affect stroke risk, none of which are part of the CHA2DS2-VASc risk score.
We should commend Chao and colleagues for the considerable effort put forth to perform and report this study. There is no doubt in my mind that when clinicians discuss anticoagulation with their AF patients with a CHA2DS2-VASc risk score of 1, the bar has been lowered; more patients will receive anticoagulant therapy, and many strokes will be prevented.
↵∗ Editorials published in the Journal of the American College of Cardiology reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology.
Dr. Calkins is a consultant for Boehringer Ingelheim, AtriCure, and Daiichi Sankyo.
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