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ASSERT-II: Subclinical AF common, not related to prior stroke in older patients

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NEW ORLEANS — Patients who have received pacemakers commonly experience short-lasting, asymptomatic subclinical atrial fibrillation episodes and an increased stroke risk, according to the results of the ASSERT-II trial presented at the American Heart Association Scientific Sessions.

"I would suggest that subclinical AF is extremely common in asymptomatic elderly patients with CV stroke risk factors and additional risk markers for AF. This is at least as common as we see in the ASSERT trial and in the CRYSTAL-AF trial,” Jeff S. Healey, MD, MSc, FRCPC, from the Population Health Research Institute at McMaster University, said in a presentation. "Interestingly, people with prior stroke or [transient ischemic attack] in our study were no more likely to have subclinical AF than other patients."

Researchers conducted a prospective cohort study at 26 sites in Canada and the Netherlands to determine subclinical incidence of AF lasting at least 5 minutes.

Jeff S. Healey

Inclusion criteria were patients aged 65 years or older with a CHADS-VASc score > 2, a history of obstructive sleep apnea, BMI over 30 kg/m², and signs of left atrial enlargement or a serum N-terminal pro-B natriuretic peptide level 290 pg/mL.

If a patient had previously documented AF or flutter, had an implanted pacemaker or defibrillator, were receiving chronic oral anticoagulation therapy or had scheduled cardiac surgery within six months, they were excluded from the study.

The 273 eligible patients who were enrolled in the study received an implantable loop recorder (Confirm DM2100, St. Jude Medical).

Patients had an average age of 74 years and 34% were women. Seventy-three percent had a history of hypertension, 25% had diabetes, 32% had vascular disease, 11% had documented sleep apnea and 20% had a history of stroke. The average CHADS-VASc score was 4.1.

Incidence measured by rate per year of subclinical AF was 34.4% (95% CI, 27.7-42.3) for episodes of at least 5 minutes, 21.8% (95% CI, 16.7-27.8) for episodes of at least 30 minutes, 7.1% (95% CI, 4.5-10.6) for episodes of at least 6 hours and 2.7% (95% CI, 1.2-5) for episodes of at least 24 hours, Healey said.

Those with subclinical AF were older (75 years vs. 73 years) than those without it (P = .008), but most other baseline characteristics between the groups did not differ, including prior stroke (subclinical AF, 52.2%; no subclinical AF, 45.8%; P = .325), he said. The exception was history of HF, which was more common in those without subclinical AF (3.3% vs. 11.4%; P = .027).

Subclinical AF was more common in those with left atrial volume of at least 73.5 ml vs. those with a volume below that (rate per year, 51.85% vs. 27.41%; HR = 1.85; 95% CI, 1.13-3.03), according to the researchers.

“The implications are really quite important, in that it substantially weakens the case of subclinical AF detection after stroke is linked to causality,” discussant, Mark M. Estes III, MD, from Tufts Medical Center. “However, perhaps the question ... is whether we should in any way change our practice based on ASSERT II.”

Healey responded that “it is perhaps premature to recommend any large change in clinical practice as a result of these data. I think this should give people pause to consider whether 45 seconds of AF a month for 6 months after stroke is really worthy of anticoagulation, because there is a lot of it out there.” – by Dave Quaile

References:

Estes MM. Healey JS. CSSR.04: Hi Impact EP Registries and Clinical Trials. Both presented at: American Heart Association Scientific Sessions; Nov. 12-16, 2016; New Orleans.

Disclosure: The study was funded in part by St. Jude Medical. Healey reports consulting and serving on an advisory board for Modest, Medtronic and Servier; receiving research grants from Bayer, Boehringer Ingelheim, Boston Scientific, Bristol-Meyers-Squibb, Medtronic, and St. Jude Medical; receiving honoraria from Bayer, Boston Scientific and Pfizer; and serving as an expert witness for Bayer. Estes reports no relevant financial disclosures.