Atrial fibrillation (AF) is the most common cardiac arrhythmia and carries some serious consequences when untreated, in particular stroke. Several recent studies have tested the use of extended cardiac monitoring for atrial fibrillation screening, whether with a wearable or implantable device, in patients with cryptogenic stroke and found high rates of silent AF.
Newer technology like small, lower cost, nonobstrusive patch devices for continuous monitoring like the Zio Patch or Medtronic’s SEEQ Patch could offer an opportunity to make atrial fibrillation screening much more scalable, practical, and cost effective. The AliveCor Heart Monitor, which offers spot rhythm checks, was tested in a large population screening study in Australia; there, it had a detection rate of 2% for silent AF.
The mSToPS study, being run out of the Scripps Translational Science Institute, will enroll a total of 2,000 patients over the age of 55 (men) or 65 (women) and a risk factor for atrial fibrillation like prior stroke, sleep apnea, or history of heart attack. Patients will be randomized to either routine care or 2-weeks of continuous ECG monitoring with the Zio patch for the first and last 2 week period of the 4 month monitoring period of time 0 to 4 months. The primary outcome will be AF detection. Secondary outcomes include costs as well as rates of stroke, heart attack, or systemic embolism.
The SCREEN-AF study is being run by several collaborating organizations in Canada including the Canadian Stroke Prevention Intervention Network and the Population Health Research Institute. They will be enrolling about 800 patients over the age of 75 and randomizing them to routine care (control) or 2-weeks of continuous ECG monitoring using the Zio Patch at the start of the study and again at 3 months. Their primary outcome is AF detection and they will be looking at a variety of secondary outcomes including initiation of oral anticoagulants, adherence, and tolerability.
Interestingly, both studies include sub-studies of other devices: a home blood pressure monitor with an irregular heart beat detector for SCREEN-AF and a heart rate sensing wristband for mSToPS. Based on the study description, it appears both devices are being tested as alternative strategies for AF screening. If effective, they would have really interesting implications for screening as these devices would be lower cost and arguably simpler in some ways. The latter in particular would have some really interesting implications for smartwatches, many of which are being outfitted with PPG-based heart rate detection.
Another fact about these trials worth noting is that they are slated to until 2017 (SCREEN-AF) and 2019 (mSToPS). So by the time study results get published around 2020, there’s a good chance today’s technology will seem pretty archaic. It’s also possible that by then, the technology supporting AF screening will be a lot cheaper which would have big effects on the ever important cost-effectiveness question as well.