The Danger of AF Without Symptoms

Lucky is hardly a word associated with suffering the symptoms of atrial fibrillation (AF).

But a paper presented as a rapid-fire oral abstract here at the European Heart Rhythm Association (EHRA) EUROPACE-CARDIOSTIM 2017 meeting suggested that experiencing AF symptoms may reduce the odds of having a serious complication from the arrthymia.

Dr Steffen Christow (Ingolstadt, Germany) presented an analysis from GLORIA-AF, which is an industry-supported global observational registry from 44 countries and more than 2200 clinical sites.^[1] Inclusion into GLORIA-AF requires newly diagnosed nonvalvular AF of less than 3 months' duration and a CHA₂DS₂-VASc score ≥1.

The idea of this study was to compare patient characteristics between asymptomatic/minimally symptomatic (EHRA Class I–II^[2]) and symptomatic (EHRA Class III–IV^[2]) patients with AF from Western Europe.

The total cohort included 6011 patients, of which 4119 (69%) were asymptomatic or minimally symptomatic and 1892 (31%) were symptomatic.

Investigators noted no significant differences in mean age (72 years) or CHA₂DS₂-VASc score (3.3).

Main finding : The incidence of prior stroke was more than twofold higher in the asymptomatic/minimally symptomatic (14.7%) vs the symptomatic group (6%) (P<0.001). TIA had occurred in 19.2% of asymptomatic/minimally symptomatic group vs 10% of the symptomatic group (P<0.001).

In his discussion, Dr Christow speculated that the higher incidence of events despite similar age and risk profiles may be explained by a longer delay in diagnosing AF in subclinical patients. These findings, he said, "underlie the importance for public programs to detect AF in an older population."

Comments

These findings are relevant because lots of people have AF without knowing it. Estimates vary, but three recent observational studies report asymptomatic AF in 13% to 39% of all patients with AF.^[3–5] Multiplying these percentages to the absolute incidence of AF globally equates to a big public-health problem.

And these are striking differences in stroke rates. I was unsure of the data when I first heard it. But this association of worse outcomes in asymptomatic AF aligns well with smaller or older observational studies. (Note that these are not short episodes of subclinical AF found on devices. The paper presented and the three I discuss below deal with AF of enough duration to discover on ECGs).

It's worse, it seems, to have AF and no symptoms. The EurObservational Research Programme AF registry reported that 1-year mortality was more than twofold higher in asymptomatic patients compared with symptomatic patients (9.4% vs 4.2%, P <0.0001).^[3] In a large database analysis of residents of Olmstead County Minnesota, Mayo researchers found a more than twofold higher risk of cerebrovascular events and a threefold higher risk of mortality (CV and all-cause) in patients with asymptomatic vs symptomatic AF.^[4]

And in the Belgrade AF study, the absence of symptoms associated with a higher risk for stroke.^[5]

Taken together, these data strongly support the rationale for AF screening.^[6] Indeed, finding higher rates of adverse outcomes in patients who don't know they have the arrthymia fulfills the first of Wilson and Jungner's^[7] classic screening criteria: the issue should be an important health problem.

But . . . that's only one step. Wilson and Jungner outlined many other criteria that a screening test must fulfill. Their words, written in 1968, apply perfectly to the debate on AF screening going on now:

The central idea of early disease detection and treatment is essentially simple. However, the path to its successful achievement (on the one hand, bringing to treatment those with previously undetected disease, and, on the other, avoiding harm to those persons not in need of treatment) is far from simple, though sometimes it may appear deceptively easy."

Mobile digital technology, watches, apps, and the like stand to turn many people who were busy living life into patients. Whether this is a good thing or not remains to be seen. Stay tuned.

JMM

Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.

Cite this: The Danger of AF Without Symptoms - Medscape - Jun 23, 2017.