BOSTON — A common stroke risk calculator can help electrophysiologists and cardiologists distinguish which patients with subclinical atrial fibrillation (SCAF) are most likely to benefit from anticoagulation from those who probably wouldn't.
"This is a great starting place where we can use CHA2DS2-VASc to put patients into three unique categories where the recommendations are to treat, don't treat, or to consider treatment," Jeff Healey, MD, of the Population Health Research Institute at McMaster University in Hamilton, Ontario, Canada, told theheart.org | Medscape Cardiology.
Healey presented results of a subanalysis of the ARTESiA trial comparing apixaban and aspirin in patients with SCAF at the Heart Rhythm Society (HRS) 2024 annual meeting. The results were published simultaneously in the Journal of the American College of Cardiology.
4 Appears to Be the Sweet Spot
CHA2DS2-VASc is a stroke risk assessment tool for people with AF that uses a scale of 0-9, with 0 the lowest risk and 9 the highest, based on age, sex, and medical history. The subanalysis broke out stroke/systemic embolism and major bleed risk by subgroups with a CHA2DS2-VASc score less than, equal to, or greater than 4.
Healy and his colleagues calculated the number of strokes prevented, and major bleeding events caused per 100 patients by anticoagulation, along with number needed to treat (NNT) for stroke prevention and number needed to harm (NNH) for bleeds at 3.5 years. The results in each CHA2DS2-VASc group were:
- < 4 — 0.4 strokes prevented (NNT = 2500) and 1.28 major bleeds (NNH = 78)
- 4 — 2.25 strokes (NNT = 44) and 0.5 bleeds (NNH = 2000)
- > 4 — 3.95 strokes (NNT = 25) and 1.7 bleeds (NNH = 59)
Healey concluded that having a score of 4 was the point at which doctors should consider anticoagulation. "Based on these data, patients with subclinical atrial fibrillation lasting between 6 minutes and 24 hours who have a CHA2DS2-VASc score of greater than 4 have an annual [stroke] risk of 2.25% per year, and we can prevent four strokes per 100 patients treated at the cost of slightly less than two major bleeds. In general, these patients should be recommended for oral anticoagulation," Healey said in presenting the results.
Patients with a CHA2DS2-VASc score equal to 4 had 2.3 fewer strokes per 100 patients with no excessive bleeding. "The use of anticoagulation is quite reasonable and should be considered but should be based on discussions and patient preference and other factors," he continued.
For those with a CHA2DS2-VASc score < 4, the stroke risk was less than 1%, and the bleeding risk was excessive, Healey said. "These patients, in general, should not receive oral anticoagulation," he said.
The subanalysis "gives clinicians a tool they already know how to use, the CHA2DS2-VASc score, and a good place where they can start, with more to follow," Healey said after he presented the results. "I think this gets people out of a confused approach to these patients where there's no clear best approach."
The findings also "shift the focus" of how to manage patients with AF, Healey added. "As arrhythmia specialists in particular, we've been very focused on arrhythmia burden and duration and these sorts of markers. We like looking at the arrhythmia, but that's not panned out as a very useful marker, at least in the range of burden that we see in these trials."
A Good Start?
The ARTESiA results, along with results from a subanalysis of the NOAH-AFNET 6 trial, put the emphasis back on clinical risk factors, Healey said. "It's a good starting reference on how to manage patients we see tomorrow," he said.
Greg Flaker, MD, professor emeritus at the University of Missouri in Columbia, Missouri, said the ARTESiA subanalysis use of the CHA2DS2-VASc calculator brings some clarity to decision-making, and the investigators deserve credit for focusing the subanalysis on device-detected AF lasting less than 24 hours, which seemed to carry the same stroke risk as no AF.
But the picture is complicated by the seemingly conflicting findings from ARTESiA and the NOAH-AFNET 6 trial, which was also presented at the meeting. That trial was halted early because it didn't show any benefit from anticoagulation with edoxaban in preventing strokes.
"Sometimes, studies are performed, and the results are clear," Flaker told theheart.org | Medscape Cardiology. "Sometimes, they shape conventional knowledge. Other times we don't get the complete picture."
He said a meta-analysis of the two trials highlights the importance of shared clinical decision-making when considering anticoagulation for AF.
Healey disclosed financial relationships with Pfizer, Bristol Myers Squibb, and Boston Scientific. Flaker had no relevant relationships to disclose.