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REVEAL-AF: Silent AF common in high-risk patients
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CHICAGO — New data from REVEAL-AF showed that approximately 30% of patients at high risk for atrial fibrillation but previously undiagnosed had silent AF.
“We know that strokes from AF are far larger and are associated with higher disability, mortality and costs; we know that the formation of an atrial thromboembolism doesn’t depend on the presence of other AF symptoms; and we also know that risk for AF-related stroke is reduced with oral anticoagulation,” researcher James A. Reiffel, MD, professor emeritus of medicine at Columbia University in New York, said during a presentation at the Heart Rhythm Society Scientific Sessions.
Therefore, he noted, clinicians should be as concerned about silent AF as they are about symptomatic AF.
In the prospective, single-arm, open-label, multicenter study, researchers sought to determine the incidence of previously undiagnosed AF using insertable cardiac monitors (Reveal LINQ or Reveal XT; Medtronic) in a high-risk population. The primary outcome was incidence of adjudicated AF lasting at least 6 minutes at 18 months.
To qualify for inclusion, patients had to have a CHADS2 score of at least 3 or a score of 2 with at least one comorbidity such as CAD, renal impairment, sleep apnea or chronic obstructive pulmonary disease. All patients were also required to have a minimum of 24 hours of external ECG monitoring within 90 days before enrollment or before device insertion.
A total of 394 patients (mean age, 72 years; 52% men) received an insertable cardiac monitor. At baseline, patients had comorbidities such as hypertension (93.7%), diabetes (62.9%) and CAD (59.1%), and 36.5% had vascular disease such as remote stroke or remote transient ischemic attack.
At baseline, 9.6% of patients had no symptoms and the remainder had nonspecific symptoms like dizziness, fatigue or shortness of breath, among others. The mean CHADS2 score was 2.9 and the mean CHAD2DS2-VASc score was 4.4.
“The population that we used to screen is a fairly typical, high-risk population that most clinicians would see in their office every day. We did not use imaging or other data that would be outside the everyday clinical criteria,” researcher Atul Verma, MD, FRCPC, FHRS, medical director of the Heart Rhythm Program at Southlake Regional Health Center, Southlake Regional Health Center, University of Toronto, told Cardiology Today.
The detection rate of AF was 6.2% at 30 days, 29.3% at 18 months and 40% at 30 months, according to the data, with a median time to detection of 123 days. Notably, AF would have gone undetected in more than three-quarters of patients if monitoring had been limited to 30 days, Reiffel said.
Additionally, incidence of AF did not differ significantly among CHADS2 subgroups (P = .23).
The researchers also evaluated time to onset of daily AF burden in the entire cohort. At 18 months, 45.8% experienced 6 minutes of AF per day, 30.9% experienced 30 minutes of AF per day, 24.2% experienced 1 hour of AF per day and 12% experienced 6 hours of AF per day. At 30 months, these percentages increased to 53.2%, 40.6%, 35.6% and 19.1%, respectively. Further, 10.2% of the 128 patients who met the primary endpoint experienced an AF episode lasting 24 hours or more.
Two sensitivity analyses were performed including all patients who exited the study prematurely. One analysis assumed all patients had AF while the other assumed no patients had AF. The incidence of AF at 18 months would have been 41.1% in the first analysis and 28.2% in the second analysis. Given the observed rate, Reiffel noted, the true incidence would likely be higher had no patients exited early.
The only independent predictors of AF were age (HR = 1.079; P < .001) and BMI (HR = 1.042; P = .0198), according to the data.
Importantly, among patients who met the primary endpoint, 56.3% were prescribed oral anticoagulants and 14.8% were prescribed rhythm control medication during follow-up.
“Not only was AF identified, but in more than half of the cases, clinicians who were following those patients felt that it was important enough to start the patients on anticoagulation or stroke prevention therapy. So, it was really actionable,” Verma said in an interview.
He noted that screening with the insertable cardiac monitor could be considered for patients with suspicious symptoms and risk factors similar to those included in the study, but more studies are required before determining that the device could be used on a wider scale. Cost-effectiveness must also be assessed, as well as patient preference, he said.
“A lot of people ask whether patients are even interested in receiving these monitors,” Verma said. “We found that uptake of the technology was surprisingly good from the patient perspective and that the complication of putting the monitor in is very low.” – by Melissa Foster
Reference:
Reiffel JA. C-LBCT02-05. Presented at: Heart Rhythm Society Annual Scientific Sessions; May 10-13, 2017; Chicago.
Disclosure: Reiffel reports financial ties with Medtronic, Portola Pharmaceuticals, Boehringer Ingelheim and Johnson and Johnson. Verma reports receiving compensation for steering committee purposes from Medtronic and grants from Biosense Webster.
Perspective
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Andrea M. Russo, MD, FACC, FHRS
These data were very exciting in that they found a surprisingly high occurrence of AF in patients who have multiple risk factors for developing stroke as well as multiple risk factors for developing AF. An incidence of 40% is even higher than we’ve seen in patients who have cryptogenic stroke.
We need to see more details about this study population, as it seems like some patients had symptoms beforehand and we will need more details about that. However, it seems that the monitor has a credible ability to detect arrhythmias without very long follow-up. It makes you think because some patients had significant durations of AF, so these data could have strong implications in that we now have ways of detecting AF.
We have ongoing studies to evaluate whether or not treatment for AF of duration less than 24 hours is going to improve outcomes, so that is a next step.
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