Usefulness of mean attenuation of pericoronary adipose tissue as a predictor of coronary microvascular dysfunction

Abstract Background/Introduction Coronary microvascular dysfunction (CMD) is a condition in which the distal microvasculature is compromised, resulting in inadequate blood flow to the subsequent arteries and myocardial ischemia. Index of microvascular resistance (IMR), which can quantify CMD, is becoming the standard for the diagnosis of CMD. Patients with CMD have a 4 to 5 times greater risk of cardiovascular death and myocardial infarction than patients without heart disease and similar cardiovascular risk. Early diagnosis of CMD may reduce cardiovascular risk and improve quality of life with therapeutic intervention. Pericoronary adipose tissue mean attenuation (PCATMA) is an indirect measure of adipocyte size and lipid content around coronary artery, reflecting inflammation status. Previous studies have shown that both PCATMA and CMD are associated with the functional severity of coronary artery disease, but no study has yet examined the relationship between PCATMA and CMD. Purpose We conducted a study comparing PCATMA in patients with and without CMD. Methods Between September 2022 and October 2023, 25 patients without significant stenosis (<50% stenosis) who underwent IMR measurement on invasive coronary angiography and coronary CT angiography (CCTA) were included. CMD was diagnosed when the IMR exceeded 25 as measured by a pressure wire inserted into the left anterior descending artery after invasive coronary angiography had excluded significant stenosis. PCATMA was measured on CCTA using the average of the values of right coronary artery, left anterior descending artery, and left circumflex artery. Multivariable logistic regression analysis with stepwise forward selection was used to assess predictors for patients with abnormal IMR. The following variables were included for adjustment: PCATMA, age, sex, diabetes, dyslipidemia, hypertension. Results The mean age of 25 patients in this study was 63 years, 48.0% were female, 29.2% had diabetes, 62.5% had dyslipidemia and 66.7% had hypertension. PCATMA was significantly higher in patients with abnormal IMR (IMR>25) (-79.6 [IQR: -82.1, -74.6] HU vs -86.3 [IQR: -89.8, -78.9] HU, p = 0.043). Multivariate logistic regression analysis demonstrated that PCATMA remained an independent predictor of patients with abnormal IMR (OR 1.27 [95% CI: 1.05–1.65], p = 0.039). Optimal cut-off value of PCATMA for predicting patients with abnormal IMR by Youden index was -82.1 HU (AUC = 0.75 [95% CI: 0.55-0.95]). Conclusions In patients without significant coronary artery stenosis, PCATMA on CCTA may be used to predict the patients with CMD, noninvasively.