Treating subclinical atrial fibrillation with blood thinners reduces risk of stroke

Jaci Fleming
March 13, 2024
Dr. Michael Gold standing next to MUSC Health banner
Dr. Michael Gold

Investigators for the worldwide ARTESIA study of over 4,000 patients report in the New England Journal of Medicine that blood thinners, or anticoagulants, can be used to reduce the risk of stroke in patients with an implanted cardiac device and subclinical atrial fibrillation (AFib). MUSC Health cardiologist and electrophysiologist Michael R. Gold, M.D., was one of only two U.S. investigators serving on the international steering committee for the trial. He also led the MUSC site of the study. 

“Pacemakers and implanted heart monitors, which track the heart around the clock, have led us to realize that there’s much more atrial fibrillation than we knew about before,” said Gold. “Some patients have atrial fibrillation that only lasts for a few seconds, a few minutes or a few hours. They may not feel it at all.” 

"Blood thinners significantly prevented having a stroke, but the trade-off for that was more bleeding. Fortunately, it wasn’t very serious bleeding.”

-- Dr. MIchael Gold

AFib is a heart arrhythmia that occurs when electrical signals in the heart fire rapidly at the same time, causing the heart to beat faster than normal. AFib interrupts normal blood flow through the chambers of the heart, causing blood to pool in the upper chambers and allowing blood clots to form. When these blood clots form in the heart, break off and travel to the brain, they block the transport of oxygen and can cause lasting brain damage, long-term disability or even death.

Clinical AFib, or AFib lasting 24 hours or longer, can cause symptoms such as heart palpitations, chest pain and dizziness and is typically treated with blood thinners. However, the role for blood thinners in subclinical AFib, or asymptomatic episodes of AFib lasting from six minutes up to 24 hours, is not well-established.

The 2012 ASSERT trial had already found that subclinical AFib detected by implanted heart devices in patients was associated with a 2.5-fold higher risk of stroke. These subclinical episodes of rapid heart rates were seen in patients with no history of clinical AFib.

Dr. Michael Gold wearing a headset 
Dr. Michael Gold in the clinic

Building on the results of the ASSERT trial, the ARTESIA investigators wanted to discover whether blood thinners would work to decrease the risk of stroke in older patients with subclinical AFib and implanted heart devices. Patients were randomized to the blood thinner apixaban (Eliquis: Bristol Myers Squibb) or aspirin.

Patients taking apixaban had a 37% lower risk of stroke than those treated with aspirin but a higher risk of bleeding. 

“Blood thinners significantly prevented having a stroke, but the trade-off for that was more bleeding,” said Gold. “Fortunately, it wasn’t very serious bleeding.”

Apixaban is an FDA-approved drug for clinical AFib, but these new findings may result in a new indication for subclinical AFib as well. 

Currently, ARTESIA only applies to patients whose AFib has been detected by an implanted heart device and whose stroke risk is elevated.

However, the findings raise the question of whether older people without implanted heart devices may also be experiencing subclinical AFib without even realizing it. Wearable technologies could be useful for heart-rate monitoring in these patients. 

“Athletic watches or other wearable devices that people have at home for monitoring their heart rate aren’t quite as accurate as implantable devices,” said Gold. “However, they’re good screening tools for identifying those who may be experiencing subclinical AFib who could benefit from treatment.”


Healey JS, et al; ARTESIA Investigators. Apixaban for stroke prevention in subclinical atrial fibrillation. N Engl J Med. 2024 Jan 11;390(2):107-117. doi: 0.1056/NEJMoa2310234.