Does the burden of atrial fibrillation matter?

“Emerging data support the concept that there may be a duration/frequency, or burden, of atrial fibrillation that is associated with a risk of stroke in AF patients,” according to Peter Zimetbaum, MD, associate professor of medicine of Harvard Medical School, during his presentation at the American Heart Association (AHA) meeting.

For patients with AF, these new data may change the way they receive anticoagulation therapy, emphasized Zimetbaum.

Zimetbaum walked AHA participants through data collected largely from studies using implanted devices that are able to accurately identify the amount of AF. The studies, he said, have raised the possibility of an association between the burden of AF and risk of stroke. The question raised by these studies is whether anticoagulation can be started and stopped based on the burden of AF.

For example, he described a study in which the heart rhythm of patients with AF was continuously recorded using cardiac electronic implanted devices (Circ Arrhythm and Electrophysiol 2015). The study found that the risk of stroke was greatest shortly after the patients developed AF, and then dropped rapidly after 10 days to normal by 30 days.

Newer studies, the TACTIC study and REACT study, are looking at devices with remote monitoring capacity, Zimetbaum said, which would allow patients to start and stop their anticoagulants based on the presence or absence of AF.

The TACIT-AF (Tailored Anticoagulation for Non-Continuous Atrial Fibrillation) pilot study is a 12-month follow-up study of 50 patients monitored for AF. Patients who are free from continuous atrial tachyarrhythmia (AT)/AF episode >6 minute duration and >6 hours total burden per day for 30 consecutive days can be withdrawn from anticoagulation. Patients with continuous AT/AF episode > 6 minutes duration per day or total burden >6 hours per day meet the criteria for initiating anticoagulation.

In the REACT.COM (Rhythm Evaluation for AnticoagulaTion with COtinuous Monitoring) study, 59 patients were monitored daily for AF. Those with an AF that lasted for >1 hour were given anticoagulation. If they remained free from AF that lasted >1 hour for 30 consecutive days, they could stop anticoagulation and start aspirin (ASA); however, they had to continue anticoagulation if not freed from AF duration >1 hour for 30 consecutive days.

The study found that with a mean follow-up of 417 days, 98.7% of patients complied with daily transmissions. A total of 18 (31%) of patients had an AF >1 hour. The total number of days on an oral anticoagulant was 1,472 days out of 24,320 days. Overall, three patients withdrew from the study, two patients experienced a major bleed while on aspirin, two patients experienced a minor bleed (two on aspirin and one on anticoagulants), and three experienced a transient ischemic attack (TIA) (two were possible and one definite). (The study is in the Journal of Cardiovascular Electrophysiology 2015).

Commentary by Michael D. Ezekowitz, MBChB, DPhil, FACC, Sidney Kimmel Medical College, Thomas Jefferson University, Broomall, Pennsylvania

Zimetbaum discussed the important and emerging role of continuous electrocardiographic monitoring of patients with or at high risk of AF. This technology is important in estimating the risk of stroke (Trends study), but also allows the diagnosis of unrecognized AF which may be silent until the patient has a stroke. For both situations, anticoagulation is effective for stroke prevention.