Afib Quiz: What’s a CHA2DS2-Vasc Score Got to do With It?

Test your knowledge of the nuances of this tool used to calculate risk of ischemic stroke in patients with atrial fibrillation (AF) and try a bonus question on how to treat postoperative AF.  

1. The CHA₂DS₂-Vasc score is an appropriate tool to stratify the risk of stroke in the absence of atrial fibrillation.

A. True

B. False

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Answer: B. False. Previous studies have shown that the CHA₂DS₂-Vasc risk score can be used to predict risk of stroke in patients with myocardial infarctions or heart failure even in the absence of atrial fibrillation given that the score is based on several vascular risk factors.  However, a recent prospective registry analysis published in JACC Interventions¹ showed that among ~4100 community outpatients without AF (mean age 62 years, 57% women, 22% black) matched with a group with AF, the absolute risk of stroke was quite low (5.3%) even among those with high CHA₂DS₂-Vasc score. The median follow-up was 14.7 years. The authors conclude that anticoagulation is not warranted to prevent stroke in the absence of AF despite an elevated CHA₂DS₂-Vasc score.¹

2. Patients enrolled in which of the following large atrial fibrillation clinical trials had the highest CHA₂DS₂-Vasc score?

A. RELY (dabigatran)
B. ROCKET-AF (rivaroxaban)
C. ARISTOTLE (apixaban)
D. ENGAGE-TIMI 48 (edoxaban)

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Answer:C.ARISTOTLE. The mean CHA₂DS₂-Vasc score in RELY² was 2.2 compared with 3.5 in ROCKET-AF.³ In ARISTOTLE,⁴ the mean CHA₂DS₂-Vasc score was 2.1 and in ENGAGE-TIMI 48⁵ was 2.8. As the choices for novel oral anticoagulants grow, recognizing the types of patients studied in the parent clinical trials will provide appropriate context for our patients in the real world. As an example, rivaroxaban (Xarelto) was studied in much sicker and higher risk patients than dabigatran (Pradaxa) or apixaban (Eliquis) so the bleeding results for this trial should be interpreted within this context. It has also been observed that CHA₂DS₂-Vasc score can identify a subset of patients at higher risk for bleeding.⁶ Therefore, understanding the baseline characteristics of these patients is fundamental to understanding the risk-benefit ratio for each of these NOACs. So, the next time you’re selecting a NOAC for a patient with AF, consider the CHA₂DS₂-Vasc score in your selection as well.

3. BONUS: AF after cardiac surgery is extremely common and can result in significant morbidity and mortality. Which of the following strategies is preferred for post-operative atrial fibrillation?

A. Rate control

B. Rhythm control

C. Either

D. Neither

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Answer: C. Either. Research presented at the American College of Cardiology Scientific Sessions 2016 in Chicago, IL and published in the New England Journal of Medicine⁷showed that there was no clear advantage to one strategy over the other and it was essentially “dealer’s choice.” Patients (N=523) without a prior history of AF who developed AF after cardiac surgery were randomized to rate control (usually with beta-blockers) vs rhythm control (with amiodarone and/or direct-current cardioversion). Both arms had similar rates of death, serious adverse events, and thromboembolic or bleeding events (including stroke) as well as hospital days. The rhythm control arm did achieve sinus rhythm sooner.

References:

1. Alraies MC, Chen LY. CRT-300.03: The use of CHA2DS2-VASc score to predict risk of stroke in general population without atrial fibrillation. J Am Coll Cardiol Intv. 2016;9(4_S):S34-S34. doi:10.1016/j.jcin.2015.12.153

2. Connolly SJ, Ezekowitz MD, Yusuf S. Dabigatran versus warfarin in patients with atrial fibrillation. N Engl J Med 2009; 361:1139-1151 DOI: 10.1056/NEJMoa0905561

3. Patel MR, Mahaffey KW, Garg J, et al. Rivaroxaban versus warfarin in nonvalvular atrial fibrillation. N Engl J Med. 2011; 365:883-891. DOI: 10.1056/NEJMoa1009638.

4. Granger CB, Alexander JH, McMurray JJV, et al. Apixaban versus Warfarin in Patients with Atrial Fibrillation. N Engl J Med 2011; 365:981-992. DOI: 10.1056/NEJMoa1107039.

5. Giugliano, RP, Ruff CT, Braunwald E, et al. Edoxaban versus Warfarin in Patients with Atrial Fibrillation. N Engl J Med 2013; 369:2093-2104. DOI: 10.1056/NEJMoa1310907.

6. Toyoda K, Yasaka M, Uchiyama S. CHADS2 and CHA2DS2-VASc scores as bleeding risk indices for patients with atrial fibrillation: the Bleeding with Antithrombotic Therapy Study. Hypertens Res. 2014;37:463-6. doi: 10.1038/hr.2013.150. Epub 2013 Nov 7.

7. Gillinov AM, Bagiella E, Moskowitz AJ, et al. Rate control versus rhythm control for atrial fibrillation after cardiac surgery. N Engl J Med. 2016 Apr 4. [Epub ahead of print]