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August 10, 2022
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In cryptogenic stroke, cardiac monitoring technology can help prevent recurrence

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In the time that it takes to read this article, at least one person will experience a stroke. Of the nearly 800,000 people in the United States who experience a stroke this year, one in four will have a second one.

More alarming, the second stroke is often more dangerous and deadly than the first.

Graphical depiction of source quote presented in the article
Peacock is an electrophysiologist at White Plains Hospital in White Plains, New York.

In my practice, these statistics mirror the question I am asked most often by patients, “What is my risk for having a second stroke?” For patients with cryptogenic stroke, these fears are exacerbated, as patients are left wondering what caused their original stroke. This only underscores just how critical it is for providers of patients with stroke to work together to identify and address the root cause of cryptogenic stroke, as well as additional risk factors that could lead to secondary stroke. For cardiologists and neurologists, open and ongoing communication is key. Together, we have the opportunity to intervene by leveraging the latest cardiac monitoring technology.

Addressing AF head on

Current research shows us that atrial fibrillation is directly and transiently associated with ischemic stroke. In fact, patients with AF have a fivefold increase in ischemic stroke risk. AF-related ischemic strokes are twice as fatal as strokes not related to AF, making it more important than ever to detect AF early and consider prescribing anticoagulation therapy that can help reduce the risk for stroke.

This adds a key understanding to the bigger picture: Undiagnosed AF may be a cause of cryptogenic strokes. But as we know, detecting AF can be challenging, since episodes happen infrequently and often without symptoms. For patients with cryptogenic stroke, this means long-term monitoring with cardiac monitoring devices is critical to potentially address an underlying, life-threatening arrhythmia, and to ultimately help prevent a recurrent stroke.

Detecting the 30:70 risk for AF

At White Plains Hospital in New York, we include long-term monitoring of our patients with cryptogenic strokes. In fact, we consider loop recorders like insertable cardiac monitors (ICMs) and cardiac implantable electronic devices (CIEDs) the standard for long-term monitoring because the data behind them are so clear.

Starting in 2014 with the landmark study CRYSTAL AF, we have strong evidence that ICMs are superior to standard monitoring for AF detection in patients with a cryptogenic stroke. The study showed that AF was detected in up to 30% of patients with cryptogenic stroke when monitored with a cardiac device over 3 years, validating the need to monitor and the importance to treat this patient population.

Evidence has only continued to build for AF detection in patients with ischemic stroke since then. Findings from the STROKE AF study showed a sevenfold increase in detecting AF at 12 months using an ICM over conventional monitoring strategies. The PER DIEM study, published in JAMA in June 2021, found that ICMs were more effective in detecting AF in patients with cryptogenic, large- and small-vessel ischemic stroke at 12 months compared with external monitors for 30 days. And now, a study published in September 2021 in JAMA Cardiology indicates a temporal relationship between AF and stroke for the first time. In 2021, the American Heart Association and American Stroke Association updated their guidelines for secondary prevention of stroke to recommend ICMs for patients with cryptogenic stroke.

CIEDs allow us to monitor our patients to identify where they fall in 30:70 split in developing AF that we saw in the CRYSTAL AF study. This has major implications for patients, as we may need to start them on anticoagulation therapy if they are among the 30% of patients that have AF.

Recurrent stroke prevention: Applying insights to practice

Sometimes a leap must be made between data and applying insights in a real-world patient setting. With loop recorders, we’ve actually seen the devices better prepare us for possible patient events. We are able to receive real-time, meaningful insights into what is happening with our patients and detect AF that may have otherwise gone unseen. We are gaining more and more data that directs us on what to watch for — for example, the September 2021 JAMA Cardiology study found that patients are most vulnerable to stroke risk within the first 5 days after an AF event, making this a key window of time to monitor. If a patient does not have an ICM, there is no way for us to know if they experience an AF episode.

AF episodes can also be infrequent, meaning short-term monitors lack real-time data and may miss an episode, delaying a patient’s diagnosis. We have several patients with cryptogenic stroke who had no history of AF and no AF on inpatient telemetry, only to have AF diagnosed by ICM within the first week of discharge. Short-term monitors and traditional long-term monitors without daily transmission would either miss or delay the diagnosis and treatment of these patients.

So where do we go from here? The key is collaboration between neurologists and cardiologists. This collaboration is critical to making sure the next step for this population of patients with stroke is a CIED. Not only does this allow us to help patients receive the best treatment pathway, but it also gives patients a sense of empowerment. Patients feel reassured that they are being monitored by their doctors at all times and are working to find dangerous, potential risk factors that could lead to another stroke. That’s our shared goal, to work together to ensure patients with stroke receive the critical multidisciplinary care they need so that we can prevent a secondary stroke.

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James Peacock, MD, MS, is an electrophysiologist at White Plains Hospital in White Plains, New York. He can be reached at jpeacock@wphospital.org.