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CRYSTAL AF: Insertable cardiac monitor superior for AF detection at 3 years
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Consistent with 6-month and 1-year results, an insertable cardiac monitor was superior to routine care at detecting atrial fibrillation in patients with cryptogenic stroke at 3 years, according to new data from the CRYSTAL AF study.
“AF can be paroxysmal and asymptomatic, thereby making detection with routine ECG methods difficult,” the researchers wrote in Circulation: Arrhythmia and Electrophysiology. “Oral anticoagulation is highly effective in reducing recurrent stroke in patients with AF, but its initiation is dependent on the detection of AF.”
They assigned 441 patients with cryptogenic stroke (mean age, 61 years; 63% men) to the insertable cardiac monitor (Reveal XT, Medtronic) or conventional monitoring.
At 3 years, AF was detected in 30% of patients assigned the insertable cardiac monitor vs. 3% of those assigned routine care (HR = 8.8; 95% CI, 3.5-22.2), an even wider gap than was seen at 6 months (8.9% vs. 1.4%) and 1 year (12.4% vs. 2%), Johannes Brachmann, MD, and colleagues reported.
Oral anticoagulation was prescribed in 94.7% of those in the insertable cardiac monitor arm detected with AF at 6 months, 96.6% in those detected at 1 year and 90.5% of those detected at 3 years, Brachmann, from the department of cardiology, Hospital Klinikum Coburg, Teaching Hospital of the University of Würzburg, Coburg, Germany, and colleagues wrote.
Of those assigned the insertable cardiac monitor, median time to detection of AF was 8.4 months, 81% had asymptomatic first AF episodes and 94.9% had at least 1 day in which AF lasted longer than 6 minutes, they wrote.
Given those figures, “it would have been unlikely to detect AF using short-term monitoring with traditional or outpatient methods in an important proportion of subjects,” Brachmann and colleagues wrote.
At 36 months, recurrent stroke or transient ischemic attack occurred in 20 patients assigned the insertable cardiac monitor and 24 assigned routine care, although the study was not powered to detect differences in that outcome, they wrote.
Five patients (2.4%) had the insertable cardiac monitor removed because of infection or pocket erosion, according to the researchers.
“Current guidelines recommend prolonged monitoring (approximately 30 days) within 6 months of a [cryptogenic stroke],” Brachmann and colleagues wrote. “However, our results strongly support use of an [insertable cardiac monitor] in [patients with cryptogenic stroke] for the detection of AF for longer periods of time.” – by Erik Swain
Disclosure: The study was funded by Medtronic. Brachmann reports receiving grants from Biotronik and Medtronic and personal fees from Biotronik. Please see the full study for a list of the other researchers’ relevant financial disclosures.
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