Mutsumi Miyauchi of 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 animals' gums, and bacterial DNA was detected in the left atrium. Moreover, atrial tissue was more fibrotic than atrial tissue in control animals 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 was six times higher in infected mice than in control mice (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 the causes were unclear. In addition to the mouse experiment, the researchers also analyzed atrial tissue from 68 patients with atrial fibrillation who had undergone heart surgery. P. gingivalis DNA was also detected in the atria of these patients, and its amount positively correlated with the area of inflamed periodontal surface (p < 0.0001) and the degree of atrial fibrosis (p = 0.002). Thus, treating periodontitis may not only improve oral health but also reduce the risk of atrial fibrillation.
