Isolated Atrial Microvascular Dysfunction in Patients With Lone Recurrent Atrial Fibrillation

Abstract

The purpose of this study was to assess atrial myocardial perfusion in patients with lone recurrent atrial fibrillation (LRAF). Although acute atrial ischemia has been implicated in the pathogenesis of atrial fibrillation, there are few data concerning human atrial myocardial perfusion and none for patients with LRAF. Sixteen patients with LRAF and 15 control subjects with suitable coronary anatomy underwent time-averaged peak coronary blood flow velocity (APV) measurements (cm/s), using a Doppler guidewire in the proximal left circumflex coronary artery (LCx) and in the left atrial circumflex branch (LACB), at baseline (b) and after adenosine administration to achieve maximal hyperemia (h). Coronary flow reserve was defined as h-APV/b-APV. Although there were no statistically significant differences in b-APV between patients with LRAF and control subjects or between the LACB and LCx, there were significant group (p = 0.002), artery (p = 0.001), and interaction (p < 0.001) effects at maximal hyperemia. In patients with LRAF, the h-APV and coronary flow reserve of the LACB (30.4 +/- 9.5 cm/s and 2.2 +/- 0.4, respectively) were significantly lower than in the LACB of the control subjects (45.8 +/- 12.8 cm/s [p < 0.001] and 2.9 +/- 0.5 [p = 0.001], respectively) or in the patients' LCx (43.0 +/- 10.9 cm/s [p = 0.001] and 3.1 +/- 0.6 [p < 0.001], respectively). This study confirms for the first time isolated atrial myocardial perfusion abnormalities in patients with LRAF and coronary flow reserve impairment, indicating that microvascular dysfunction is a pathophysiological substrate associated with this arrhythmia.