AIM To explore the causal relationship between endometriosis (EMs) and cardiovascular disease (CVD) using bidirectional two-sample Mendelian randomization method.

METHODS Based on the summary data from genome-wide association studies, inverse variance weighting (IVW) was used as the main analysis method, MR-Egger regression, weighted median estimation, simple model and weighted model were used as auxiliary analysis methods, and genetic variants were used as instrumental variables to analyze the association between EMs and 6 common CVD (including: angina pectoris, myocardial infarction, coronary heart disease, heart failure, cardiac hypertrophy, hypertension). Sensitivity analysis was further performed by Cochran's Q test, MR-egger regression, and leave-one-out method to test the heterogeneity, horizontal pleiotropy and robustness of instrumental variables. At the same time, the effects of the above 6 CVD on EMs were analyzed by similar methods to explore the possible reverse causality.

RESULTS IVW analysis showed that EMs was significantly associated with angina pectoris (OR = 1.11, 95% CI: 1.02～1.21, P<0.05), myocardial infarction (OR = 1.10, 95% CI: 1.02～1.17, P<0.01) and coronary heart disease (OR = 1.08, 95% CI: 1.01～1.15, P<0.05). The results of Cochran's Q test, MR-egger regression and leave-one-out method showed that the results were robust. None of the above six CVD showed causal effect on EMs.

CONCLUSION Endometriosis has positive causal effects on angina pectoris, myocardial infarction, and coronary heart disease.