The Importance of Atrial Fibrillation's Associated Comorbidities as Clinical Presentation and Outcome Contributors.

Atrial fibrillation (AF) has a heterogeneous clinical presentation. It can occur: (a) in the presence or absence of detectable heart disease, and, (b) with or without relatedsymptoms. Its prognosis in terms of thromboembolismand mortality is most benign when applied to young individuals (aged less than 60 years) without clinical orechocardiographic evidence of cardiopulmonary disease [termed "lone AF"]. However, by virtue of aging or because of the development of concomitant cardiovascular disorders, patientsmove out of the lone AF category over time, accompanied by increased risks for thromboembolism and mortality. Thus, underlying and/or associated comorbidities must play an important role in the presentation and consequences of patients with AF. While, no doubt, most clinicians likely appreciate that the majority of the AF patients they see have associated cardiovascular, pulmonary, metabolic, endocrinologic, genetic, and/or other disorders, it is not clear how much they appreciate that these disorders directly relate to the presenting symptoms and to the risks from AF in addition to their role as risk factors (or markers) for AF. This issue is the subject of this review manuscript.