Atypical Afib May Augur Poor Prognosis

“Do you feel it when you’re in atrial fibrillation?” 

This is a question I assume we all ask our patients with paroxysmal atrial fibrillation (AF). I always ask it because, if symptomatic, it helps me to ascertain the burden of disease and also steers me towards a rhythm control strategy. Little did I know that the answer to the question also offers important prognostic information.

Recent data presented by authors from the Mayo Clinic and reported in HeartRhythm suggest that there is a much higher risk of adverse outcomes in patients with AF who are either asymptomatic or have atypical presentations (with a typical presentation being described as palpitations). These outcomes, ascertained over approximately 6 years of follow-up, included a 2.7X higher risk of cerebrovascular events, 3.1X higher risk of cardiovascular mortality and a 3X higher risk of all-cause mortality after adjustment for age and CHA2DS2-VASc score; further adjustment for comorbidities and warfarin use did not significantly alter these findings. Surprisingly, out of the 476 cases studied, a minority (40%) were typical presenters with palpitations; 26% had atypical symptoms (fatigue, dyspnea, lightheadedness); and 34% were completely asymptomatic. The typical presenters had a lower CHA2DS2-VASc score as compared to the atypical presenters. Complicated AF presenters, such as those with heart failure or thromboembolism as initial presentation, or those in whom presence or absence of symptoms could not be well delineated were excluded.

Findings of the study, qualified by its small size and non-randomized observational nature, provide some valuable insights for clinical practice surrounding diagnosis and treatment of AF.  First, the majority of AF patients we see may be asymptomatic or have atypical symptoms.  So, our threshold for screening for AF, which is so prevalent, must remain low.  Second, this is the first report on the clinical implications for prognosis of symptomatic vs. asymptomatic/atypical presentations of new-onset AF. The reasons for the dramatic findings remain unclear but the authors postulate several hypotheses that need further study: (1) Patients and providers may recognize typical symptoms earlier, leading also to earlier treatment; (2) Asymptomatic or atypical AF is a heterogeneous type of AF that confers differential risk; or (3) Absence of symptoms is a surrogate marker for a sicker patient population. 

I know that, based on these findings, the question, “Do you feel it when you’re in AF?” has suddenly taken on a whole new meaning in my practice.

Source:

Siontis KC, Gersh BJ, Killian JM, et al. Typical, atypical, and asymptomatic presentations of new-onset atrial fibrillation in the community: characteristics and prognostic implications. HearthRhythm. 2016 DOI: http://dx.doi.org/10.1016/j.hrthm.2016.03.003