A growing body of evidence suggests that the underlying cause for many cryptogenic strokes is atrial fibrillation (AF). However, many of these patients do not receive additional cardiac monitoring after an initial stroke work up, leaving them at risk for a recurrent stroke. To address this issue, a new multidisciplinary Cryptogenic Stroke Pathway was developed by Lynn Hundley, Kent Morris and Nadeem Talpur at Norton Healthcare in Louisville, USA. The pathway includes a joint collaboration between neurologists, electrophysiologists, cardiologists and other stroke care health professionals and incorporates long-term monitoring with an implantable cardiac monitor. In this commentary, Hundley, Morris and Talpur explain the details of this pathway and its positive outcomes.
Stroke is the leading cause of long-term disability,1 impacting 15 million people worldwide.2 Ischaemic strokes account for 85% of all strokes. Of these ischaemic strokes, approximately 25‒40% are deemed “cryptogenic,” or a stroke of unknown cause.3
As clinicians, it is critically important to understand the root cause of cryptogenic strokes to prevent recurrence as secondary strokes have a higher rate of death and disability.4
For cryptogenic stroke patients, a growing body of evidence suggests that the underlying cause for many is atrial fibrillation (AF), a common and often undertreated heart rhythm disorder. AF is a major risk factor for stroke, increasing risk by five-fold on average.5 Strokes caused by AF are twice as likely to be fatal than non-AF strokes.6 When these stroke patients receive in-hospital care, many do not receive additional cardiac monitoring after an initial stroke work up. This practice leaves stroke patients at risk for a recurrent stroke.
At Norton Healthcare in Louisville, USA, our goal is to provide state-of-the-art, evidence-based care so that every stroke patient has an opportunity for the best possible outcome. It is in this spirit that we developed a Cryptogenic Stroke Pathway that promotes a multidisciplinary collaboration between neurologists, electrophysiologists, cardiologists and other stroke care health professionals by incorporating long-term monitoring with an implantable cardiac monitor.
AF and long-term cardiac monitoring
Diagnosing AF is challenging as paroxysmal AF episodes are unpredictable, intermittent, and in many cases, do not cause symptoms.7 Historically, a stroke work up has included electrocardiogram, hospital telemetry, and short-term event or Holter monitoring as the standard of care for AF detection with 30-day or longer monitoring only occasionally employed. However, a significant and growing body of evidence supports longer-term monitoring for AF with an implantable cardiac monitor in this patient group as a best practice.
One such study is CRYSTAL AF, which concluded that long-term monitoring with the Reveal LINQ Insertable Cardiac Monitor (ICM) from Medtronic was superior to standard medical care for AF detection in patients with cryptogenic stroke, and found that the median time to AF detection was 84 days—making the practice of 30-day monitoring or less suboptimal.8 The recommendation for long-term cardiac monitoring has also been reinforced in neurology clinical practice guidelines, and was recently incorporated in the Clinical Practice Guidelines on Atrial Fibrillation by the European Society of Cardiology.
Cryptogenic Stroke Pathway at Norton Healthcare
Norton Healthcare is one of the top 100 healthcare delivery systems in the USA, and has achieved advanced certification by the Joint Commission for all four of its adult hospitals; three are primary stroke centres and one is a comprehensive stroke centre.
In 2013, we began a multidisciplinary collaboration to build a Cryptogenic Stroke Pathway. Given the increasing body of evidence that shows a significant number of cryptogenic strokes may be due to occult AF, we felt this was critical to implement in order to prevent future morbidity and mortality in our patients due to recurrent stroke. Our team initially attended a multidisciplinary stroke conference during which we outlined our initial pathway by building upon our existing stroke protocol. Then, the referral process and monitoring protocol were determined. As part of this process, after a stroke is deemed cryptogenic by the neurology team, the cardiologist is then consulted for TEE, if appropriate, and for an implantable cardiac monitor implantation; this is then completed prior to discharge when possible (Figure 1 shows the Cryptogenic Stroke Pathway protocol at Norton Healthcare).
As a result, 308 patients to date have received a Reveal LINQ ICM. Of these, AF was detected in 23 patients for a current detection rate of 7.5%. It is important to note that 15 of the 23 AF detections were greater than 30 days (65%)—meaning that these patients would not have had their AF detected with traditional, short-term cardiac monitoring methods. Following AF detection, all patients were then started on oral anticoagulation with the agent that was identified as optimal for them.
Getting your Cryptogenic Stroke Pathway started
Before you start a Cryptogenic Stroke Pathway, below are some insights to help with implementation:
The groundwork: Initial efforts at Norton Healthcare included identifying physician champions from cardiology, electrophysiology and neurology; defining the Cryptogenic Stroke Pathway; and coordinating the implant procedure amongst multiple hospital locations and outpatient implantable cardiac monitor follow-up.
Openly communicate and define roles: Establishing effective channels of communication early was critical to the success of our programme because it allowed for rapid feedback and improvement of our pathway, as well as timely communication of results and treatment changes for patients. The relationship and communication between the cardiology and neurology teams is paramount. This importance cannot be overstated as the success of your programme will depend on this relationship.
Identify barriers (overcoming challenges): Initial challenges in our programme included underestimating the importance of communication needed to bring stakeholders fully on board with the pathway, and the need to more clearly define roles post implantable cardiac monitor implant in regard to communicating results with providers and patients. To address these challenges, we conducted educational events both at outset and periodically. We also facilitated ongoing discussions with the Cryptogenic Stroke Pathway team, which centred on process refinement to improve and streamline results, communication and tracking.
Measure success: As each AF detection represents a potential stroke prevented and improvement in the lives of our patients, measuring success by tracking implants, detections, timing of detections and anticoagulation starts was critically important.
Stroke survivors that leave your hospital with an undetermined cause of their stroke are at great risk. We are obliged to find the cause and provide secondary prevention, or we have not served our patients well. Identifying AF and starting anticoagulation greatly decreases the risk of recurrent stroke, thereby decreasing risk of further disability or even death. New, long-term monitoring technology has provided us with a tangible way to make a change in secondary stroke prevention. It is vital that neurologists and cardiologists form relationships, communicate and collaborate to manage, diagnose and treat stroke patients. By forming these working relationships through a Cryptogenic Stroke Pathway, you can begin working together to help reduce recurrent strokes and improve outcomes for your stroke patients.
1. Mozaffarian D, Benjamin EJ, Go AS, et al. Heart disease and stroke statistics—2015 update: a report from the American Heart Association. Circulation 2015;e29‒322
3. Adams HP, Jr, Bendixen BH, Kappelle LJ, et al. Classification of subtype of acute ischaemic stroke. Definitions for use in a multicenter clinical trial. TOAST. Trial of Org 10172 in Acute Stroke Treatment. Stroke 1993;24:35‒41
5. Wolf PA et al. Stroke 1991;22:983‒988
6. Lin HJ et al. Stroke 1996;27:1760‒1764
7. Kamel. Detection of atrial fibrillation and secondary stroke prevention using telemetry and ambulatory cardiac monitoring. Curr Atheroscler Rep 2011;13:338‒343
8. Sanna T, Diener HC, Passman RS, et al. Cryptogenic stroke and underlying atrial fibrillation (CRYSTAL AF). N Engl J Med 2014;370(26):2478‒2486
Lynn Hundley is Clinical Effectiveness director for the Stroke Program at Norton Healthcare, Louisville, USA. Kent Morris is a cardiologist/electrophysiologist also at Norton Healthcare and Nadeem Talpur is medical director for the Stroke Program also at Norton Healthcare