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Atypical and asymptomatic presentations of atrial fibrillation are associated with a roughly tripled risk of poor outcomes, a population-based study showed.

Patients with symptoms other than the typical palpitations upon presentation had a than did those with a normal Afib presentation, after adjustment for age and CHAD₂DS₂-VASc score (95% confidence interval 1.65-7.48).

For those with asymptomatic Afib upon presentation, multiple risks were higher, , of the Mayo Clinic in Rochester, Minn., and colleagues reported online in HeartRhythm. The adjusted hazard ratios compared with typical symptomatic Afib were:

• 2.70-fold elevated risk of cerebrovascular events (95% CI 1.29-5.66)
• 3.12-fold higher risk of cardiovascular mortality (95% CI 1.50-6.45)
• 2.96-fold elevated risk of all-cause mortality (95% CI 1.89-4.64)

The associations remained statistically significant after further adjustment for comorbidities and warfarin (Coumadin) use, as well in the study of 1,000 randomly selected incident cases of Afib in Olmsted County, Minn., near the Mayo Clinic from 2000 through 2010.

Of the 476 uncomplicated cases, 40% were typical presentations with palpitations, 26% had nontypical symptoms (such as fatigue, dyspnea, or lightheadedness), and 34% were asymptomatic. During about 6 years of follow-up, 59 cerebrovascular events and 149 deaths occurred in this population.

"The type of clinical presentation may have important implications for the prognosis of new-onset AF in the community," the researchers concluded, adding that "it is possible that the ability of CHA₂DS₂-VASc score-based schemes to discriminate between low, intermediate, and high-risk patients can be improved by consideration of AF symptoms."

There are also implications for early recognition by patients and providers from the fact that only a minority of Afib patients had a typical presentation and about one in 10 presented with a complication (thromboembolism or heart failure) as the first Afib manifestation.

"We did not investigate whether these patients [with complications] had preceding AF symptoms but this observation highlights the importance of AF symptom awareness and has implications for population screening among high-risk groups," Chamberlain's group wrote.

Prior studies have shown no effect or even lower risk for asymptomatic Afib, although their inclusion of secondary Afib might have confounded the findings, they noted.

This study likewise couldn't determine the reason for the difference in prognosis among the groups.

"It is possible that patients with typical symptoms seek medical attention earlier compared to patients with no or atypical symptoms. In the myocardial infarction paradigm, the delay in recognition and delivery of treatments has been recognized as the mediator of adverse outcomes in patients with atypical ischemic symptoms," the researchers wrote.

However, "as the typical AF population had an overall lower risk profile, it is possible that the more favorable outcomes reflect the cardiovascular and general health fitness that statistical adjustments are not able to account for (due to unmeasured confounders)."

From the American Heart Association:

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