To explore the relationship between heart rate variability and coronary flow velocity reserve (CFVR) during adenosine infusion in female patients with non-obstructive coronary artery disease.

This was a single-center retrospective study. Consecutive female patients with suspected angina presenting to People's Hospital of Liaoning Province with stenosis diameter ＜50% on coronary angiography within 3 months and undergoing transthoracic echocardiography at our hospital from November 2018 to November 2020 were selected. Clinical data, conventional echocardiographic parameters, hemodynamic parameters before and after adenosine infusion, and CFVR results were collected, and the patients were divided into either a case group (CFVR＜2) or a control group (CFVR≥2) according to CFVR. The clinical characteristics of patients in the two groups were compared, and linear correlation between CFVR and each variable was assessed using correlation analysis, and multiple linear regression analysis was used to explore the risk factors associated with microcirculatory dysfunction (CMD).

A total of 60 female patients were included. Univariate analysis showed that age, peak systolic and diastolic blood pressure, resting heart rate, proportion of diabetes mellitus, proportion of hypertension, and proportion of hyperlipidemia were significantly higher, and heart rate reserve (HRR) was significantly lower in the CMD group than in the control group (P＜0.05). Correlation analysis showed that CFVR was moderately positively correlated with HRR (r=0.490, P＜0.001) and weakly negatively correlated with age (r=-0.390, P＜0.05), hyperlipidemia (r=-0.312, P＜0.05), and baseline heart rate (r=-0.327, P＜0.05). Multiple linear regression analysis showed that CFVR remained independently correlated with HRR after adjusting for hypertension, diabetes, hyperlipidemia, age, peak diastolic blood pressure, peak systolic blood pressure, and baseline heart rate (β=0.391, P＜0.05). ROC curve analysis showed that the area under the curve of HRR for prediction of CMD was 0.85 (P＜0.001), and 35% was the best cut-off value of HRR, with a sensitivity and specificity of 71% and 88%, respectively.

HRR is associated with abnormal CFVR in female patients with nonobstructive coronary artery disease and may contribute to risk stratification of CMD in such patients.