The incidence of previously undiagnosed atrial fibrillation (AFib) may be substantial in patients who have AFib and stroke risk factors, according to data from the REVEAL AF study presented on Aug. 26 as part of the ESC Congress 2017 in Barcelona and simultaneously published in JAMA Cardiology.

Using an insertable cardiac monitor (ICM) for 18 to 30 months, researchers monitored a total of 385 patients (52.2 percent male/mean age of 71.5 years) from the United States and Europe with a CHADS2 score of three or greater (or a score of two with at least one additional risk factor) between November 2012 and January 2017. Roughly 90 percent of enrolled patients had nonspecific symptoms like fatigue, dyspnea and/or palpitations that could be compatible with AFib. The primary endpoint was adjudicated AFib lasting six or more minutes and was assessed at 18 months.

Results showed a 29.3 percent detection rate of AFib lasting six or more minutes at 18 months. Additionally, incidence of AFib at 18 months was similar among patients with CHADS2 scores of two (24.7 percent), three (32.7 percent) and four or greater (31.7 percent) (p = 0.23).  Researchers also noted detection rates at 30 days and six, 12, 24 and 30 months were 6.2 percent, 20.4 percent, 27.1 percent, 33.6 percent and 40.0 percent, respectively. Median time from device insertion to the first detection of an AFib episode was 123 days. Thirteen of the patients (10.2 percent) who reached the primary endpoint had one or more episodes lasting 24 hours or longer, and oral anticoagulation therapy was prescribed for 72 patients (56.3 percent).

The researchers, led by James A. Reiffel, MD, FACC, note that AFib would have gone undetected in this specific patient population had ICM monitoring been limited to 30 days. “As the AFib incidence was still rising at 30 months, the ideal monitoring duration is unclear,” they write. “Our findings have important implications for AFib screening and stroke prevention in this population.” They suggest additional trials assessing the value of detecting subclinical AFib and of prophylactic therapies are warranted.

In a related editorial comment, Jeff S. Healey, MD, MSc, writes: “The REVEAL AF study has shown that AFib is extremely common among older individuals with stroke risk factors. Over the next three to four years, subgroup analyses, economic evaluations and randomized clinical trials will help determine if this insight can be translated into a cost-effective stroke prevention strategy for high-risk individuals.”

Keywords: ESC Congress, ESC2017, Atrial Fibrillation, Cost-Benefit Analysis, Stroke, Heart Conduction System, Monitoring, Physiologic, Dyspnea

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