The gut microbiota differs between patients with coronary artery disease (CAD) and healthy controls; however, it currently remains unclear whether these differences exist prior to the onset of CAD. We herein investigated the gut microbiota associated with subclinical coronary artery calcification (CAC) in a Japanese population.

A total of 663 Japanese men were enrolled in this cross-sectional study. Computed tomography and gut microbiology tests were performed, and CAC scores were calculated using the Agatston method. Participants were categorized into 4 groups based on their CAC scores: CAC = 0, 0 <CAC ≤100, 100 <CAC, and with a CAD history. The bacterial 16S ribosomal RNA gene was amplified, and DNA sequencing was conducted on a MiSeq System. QIIME2 and LEfSe were used to analyze the gut microbiota, and the results obtained were compared among the 4 CAC categories.

The mean age of participants was 68.4 years (46-83 years). The numbers of participants in CAC = 0, 0 <CAC ≤100, 100 <CAC, and with a CAD history were 219, 200, 193, and 51, respectively. The medians of the Firmicutes to Bacteroidota ratio were 1.50, 1.52, 1.67, and 1.80 for each CAC category (P = .020). One standard deviation higher phylum Firmicutes, class Bacilli, and order Lactobacillales were associated with a 1.3- to 1.4-fold higher risk of CAD. These taxa were also associated with a higher CAC score category. The family Streptococcaceae and genus Streptococcus showed a higher risk of CAD. The order Enterobacterales and family Enterobacteriaceae correlated with CAC scores. The genus Blautia showed a preventive direction for CAD but did not correlate with CAC scores.

The gut microbiota significantly differed from the phylum to genus level in a manner that was dependent on CAC scores, even before the onset of CAD.