RESUMO
BACKGROUND: Injury to the heart causes hematopoietic progenitor cells (HPCs) to migrate to the site of damage and to undergo cell differentiation. Studies suggest that myocardial progenitor cells invade atrial tissue. So far it is unclear, however, whether an atrial disease per se affects circulating HPCs. METHODS AND RESULTS: Seventeen patients with persistent atrial fibrillation (persistAF), 12 with paroxysmal AF (paroxAF), and 17 matched patients with sinus rhythm (SR) were studied. HPCs (CD34+ and CD34+/CD117+) were quantified with the use of a fluorescence-activated cell sorter; stromal cell-derived factor-1alpha (SDF-1alpha), vascular endothelium growth factor (VEGF), and atrial natriuretic peptide (ANP) were determined by immunoassays. In patients with persistAF, blood samples were obtained before as well as 10 minutes, 24 hours, and 48 hours after electrical cardioversion. CD34+HPCs (AF, 7.0+/-2.3x10(3)/mL versus SR, 5.0+/-1.6x10(3)/mL; P<0.01) were increased during persistAF only. Highest SDF-1alpha levels were also observed during persistAF. Successful and unsuccessful cardioversion decreased CD34+HPCs temporarily (7.0+/-2.3x10(3)/mL versus 24 hours: 5.0+/-1.5x10(3)/mL; P<0.05). Forty-eight hours after successful cardioversion, SDF-1alpha and CD34+HPC levels started to decline, reaching control levels after 59+/-19 days. CD34+/CD117+ and VEGF levels, however, were increased by DC energy but not by AF. ANP levels correlated with CD34+HPC (r=0.76; P<0.01) and SDF-1alpha (r=0.56; P<0.01). HPCs from patients with AF had a greater tendency to differentiate into cells expressing (cardio)myocyte markers ANP and myocyte enhancer factor-2. CONCLUSIONS: PersistAF appears to increase the potential of HPCs for (cardio)myogenesis. Restitution of CD34+HPC levels, mediated by SDF-1alpha and possibly ANP, occurs within several weeks after successful cardioversion.