Objective  To analyze the distribution and composition of intestinal flora in Tibetan patients with coronary artery heart disease (CHD) on the Qinghai-Tibet Plateau.

  Methods  From September 2018 to September 2020, following patients were recruited: Tibetan CHD patients living in the area of Qinghai-TibetPlateau altitude 3600-4500 m, Tibetan patients at high altitudes with CHD (HTC), healthy people (normal Tibetans at high altitudes(HTN), Han patients with CHD living in Xining altitude 2260 m, Han CHD at a middle altitude (MHC) and Wuhan altitude 13 m, Han CHD at a low altitude(LHC), for a long time. Among them, HTC and MHC were all from inpatients of the Department of Cardiology, Affiliated Hospital of Qinghai University. HTN were all from the Physical Examination Center of the Affiliated Hospital of Qinghai University, and LHC were all from inpatients of the Department of Cardiology, the Union Hospital Affiliated to Huazhong University of Science and Technology. The fecal samples were collected, and the 16S rRNA V3-V4 regions of the intestinal flora were DNA sequenced and bioinformatic analysis was performed.

  Results  A total of 36 CHD patients (8 HTC, 14 MHC, 14 LHC) and 34 HTN patients that met the inclusion and exclusion criteria were enrolled. α-diversity analysis showed that there was no significant difference in the Shannon index of intestinal flora between HTC and HTN (P=0.091), the Shannon index of intestinal flora in HTC was the highest, followed by MHC, and the lowest in LHC(P=0.025). β-diversity analysis showed that the intestinal flora distribution of HTC was significantly different from that of HTN, MHC and LHC. In the analysis of the composition of intestinal flora, HTC also showed different characteristics from MHC and LHC at the phylum level and genus water. The relative abundance of its pathogenic bacteria, i.e. Streptococcus, Escherichia_Shigella and Klebsiella decreased; the beneficial bacteria, i.e. Faecalibacterium, Prevotella, Catenibacterium and Lactobacillus, were increased in relative abundance.

  Conclusions  The intestinal flora of high-altitude Tibetan patients with CHD showed polymorphisms that were different from those of healthy Tibetans at the same altitude and CHD patients at medium and low altitudes.