Mutsumi Miyauchi from Hiroshima University and colleagues infected the gums of mice with a highly pathogenic strain of Porphyromonas gingivalis, a bacterium that causes periodontitis. After 18 weeks, abscesses characteristic of periodontitis were found in the gums of the animals, and the DNA of the bacteria was detected in the left atrium. Moreover, the atrial tissue was more fibrotic compared with the atrial tissue of animals from the control group, not infected with P. gingivalis (21.9 percent versus 16.3 percent, p = 0.0003), and the likelihood of developing atrial fibrillation during intracardiac stimulation in infected mice was six times higher than in mice from the control group (30 percent versus 5 percent, p = 0.04). The study was published in Circulation.
Previously, scientists had found a link between periodontitis and the development of atrial fibrillation, but its causes were unclear. In addition to the experiment conducted on mice, the researchers also analyzed atrial tissue from 68 patients with atrial fibrillation who had undergone heart surgery. P. gingivalis DNA was also found in the atria of these patients, and its amount positively correlated with the area of the inflamed periodontal surface (p < 0.0001) and the degree of atrial fibrosis (p = 0.002). Thus, the treatment of periodontitis can have a positive effect not only on oral health, but also reduce the risk of atrial fibrillation.