Over an 18-month period, small, insertable cardiac monitors detected atrial fibrillation in 29% of previously undiagnosed patients who were at high risk of both AF and stroke, and in 40% of patients over 30 months, according to investigators. The study was presented at the annual congress of the European Society of Cardiology and simultaneously published in JAMA Cardiology.
More than half (56%) of patients consequently started oral anticoagulation therapy, noted James A. Reiffel, MD, of Columbia University College of Physicians and Surgeons, New York, with his associates, for the REVEAL AF investigators.
“The incidence of previously undiagnosed atrial fibrillation may be substantial in patients with risk factors for AF and stroke,” they concluded. “Atrial fibrillation would have gone undetected in most patients had monitoring been limited to 30 days. Further trials regarding the value of detecting subclinical AF and of prophylactic therapies are warranted.”
Atrial fibrillation affects millions worldwide and is associated with older age, hypertension, diabetes, and heart failure, all of which also independently increase the risk of stroke. Minimally invasive prolonged electrocardiographic monitoring with insertable cardiac monitors might help hasten detection and treatment of AF, but diagnostic yield in high-risk patients has been unclear.
In this single-arm, multicenter, prospective study, researchers inserted Reveal XT or Reveal LINQ (Medtronic) cardiac monitors in 385 adults who had either CHAD2 scores of 3, or CHAD2 scores of 2 and one additional risk factor for AF, such as coronary artery disease, sleep apnea, chronic obstructive pulmonary disease, or renal insufficiency. The primary endpoint was AF lasting at least 6 minutes (JAMA Cardiol. 2017 Aug 26. doi: 10.1001/jamacardio.2017.3180). Median follow-up time was 22.5 months. Rates of detecting AF were 6% at 30 days compared with 20% at 6 months, 27% at 12 months, 34% at 24 months, and 40% at 30 months. Patients typically had their first AF episode about 4 months (median, 123 days) after the device was inserted. Among patients who had experienced AF by 18 months, 10% had one or more episodes lasting at least 24 hours, and 72 (56%) were prescribed oral anticoagulation therapy.
The recent PREDATE AF and ASSERT-II studies also found that previously undiagnosed AF was common among high-risk patients, the researchers noted. However, whether anticoagulating patients who have only brief episodes of AF significantly reduces their risk of stroke remains unclear, they added. Three trials (ARTESiA, NOAH, and LOOP) are underway to assess whether oral anticoagulation therapy improves outcomes in patients with device-detected AF.
Medtronic funded the study. Dr. Reiffel and five coinvestigators disclosed consulting for and receiving “modest honoraria” from Medtronic. Two other coinvestigators reported employment with and stock ownership in Medtronic.
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