C-Reactive protein in lone atrial fibrillation.

An inflammatory cause of atrial fibrillation (AF) has been proposed on the basis of the presence of lymphocytic infiltrates in the biopsy results of patients with lone AF, alterations of C-reactive protein (CRP) and interleukin-6 levels in subjects with AF, and the time course of postoperative AF. Many previous studies exploring inflammatory factors in AF have been confounded by concomitant medical illnesses. Subjects with lone AF provide a unique opportunity to eliminate the effects of associated conditions. We therefore sought to determine CRP levels in homogenous cohorts of patients with lone AF or AF and hypertension. One hundred twenty-one subjects with lone AF, 52 subjects with AF and hypertension, and 75 control subjects were enrolled and studied. Plasma CRP levels were determined using a commercially available immunoassay. There was no significant difference in CRP levels between subjects with lone AF and controls (1.34 vs 1.21 mg/L, p = 0.18). CRP levels in subjects with AF and hypertension were elevated compared with those of controls and those of subjects with lone AF, although this difference was attributable to increased body mass indexes. CRP levels were not elevated in subjects with lone AF compared with controls. In conclusion, these findings clarify previous observations of elevations in CRP levels in subjects with AF and suggest that this marker of systemic inflammation is associated not with the arrhythmia per se, but rather with underlying cardiovascular disease.