Medtronic, Inc. (MDT) announced that positive results from the CRYSTAL AF (CRYptogenic STroke And underLying Atrial Fibrillation) Clinical Trial were published in the June 26, 2014 issue of The New England Journal of Medicine. The results validated the efficacy of the company's Reveal XT Insertable Cardiac Monitor (ICM.V) in identifying atrial fibrillation (AF) in patients, who had cryptogenic stroke.
A Brief Note about the Trial
In simple terms, stroke refers to loss of brain function which occurs when a blood vessel in the brain ruptures or is suddenly blocked. Stroke without an obvious explanation is termed “cryptogenic”.
Notably, patients with AF are five times more prone to suffer a stroke. However, in most cases, AF goes undetected in cryptogenic stroke patients due to lack of symptoms. In the study, 79% of the first AF episodes detected did not have any symptoms.
CRYSTAL AF – the largest global randomized clinical trial – compared continuous electrocardiographic (:ECG) monitoring with ICM to standard care for the detection of AF in patients who have suffered from recent cryptogenic strokes.
The purpose of this trial was to determine the effective duration and the most suitable type of monitoring that will increase the detection rate of AF in cryptogenic stroke patients.
The trial comprised a randomized, controlled study of 441 patients conducted at 55 centers across Europe, Canada and the U.S. from June 2009 to April 2012.
The continuous monitoring arm used the Reveal ICM to assess whether this technique can detect AF more effectively in patients with cryptogenic stroke, compared to conventional follow up. The Reveal ICM possesses an algorithm to automatically detect AF as well as other cardiac arrhythmias.
Effective detection of AF in patients who do not reveal any symptoms will eventually help determine the number of patients who suffer from incidences of cryptogenic stroke.
The study met its primary endpoint (the time to first detection of AF within 6 months of follow-up) by demonstrating that continuous monitoring with the Reveal ICM detected AF in 6.4 times more patients than standard care within 6 months. By 6 months, AF had been detected in 8.9% of patients in the ICM group against 1.4% of patients in the control group who were given standard care.
The Trial also reached its secondary endpoint (the time to first detection of AF within 12 months) by proving that within 12 months, the Reveal ICM discovered AF in 7.3 times more patients, compared to traditional care. By 12 months, AF had been detected in 12.4% of patients in the ICM group compared with 2% of patients in the control group.
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