The relationship between coronary microvascular dysfunction and left ventricular longitudinal systolic function in patients with diabetes mellitus
Authors: Wang Y , Zhao Y U E , Wang Y A N , Liu L P , Ma X J 
Published: October 2024

Abstract

Background
Coronary microvascular dysfunction (CMD) often accompanies diabetes mellitus (DM), leading to myocardial ischemia despite normal or mildly narrowed coronary arteries (&lt;50% stenosis). CMD causes myocardial hypoperfusion, resulting in impaired systolic function. Coronary flow reserve (CFR) serves as a marker of microvascular function, particularly in the absence of significant epicardial coronary stenosis. Myocardial contrast echocardiography (MCE) is a key tool for clinically assessing CFR. Global longitudinal strain (GLS) derived from two-dimensional speckle tracking echocardiography (2D-STE) offers early insights into left ventricular systolic dysfunction during subclinical stages but is underexplored in diabetic CMD patients.

Objective
This study aimed to assess myocardial microcirculatory dysfunction in diabetic patients using stress myocardial ultrasound enhancement imaging, investigate its relationship with left ventricular longitudinal systolic function, and evaluate the utility of 2D-STE in assessing left ventricular systolic function in CMD patients. The findings provide insights for early detection and prevention of left ventricular longitudinal systolic dysfunction in diabetic patients with myocardial microcirculatorydysfunction.

Methods
Seventy type 2 diabetic patients who underwent coronary CT or angiography within the past three months without obstructive coronary artery disease were included. Clinical data, biochemical parameters, and blood glucose levels were collected. Left ventricular longitudinal strain indices were obtained using 2D-STE, and microvascular function was assessed based on CFR measured via transthoracic stress MCE. Patients were categorized into CMD (CFR&lt;2) and control (CFR≧2) groups, with clinical and echocardiographic parameters compared. Strain parameters included GLS at rest, GLS under stress, and ∆GLS. Correlations between these indices and CFR were analyzed.

Results
1. Seventy patients, with 41 males (41.4%) and 58 females (58.6%), averaging 56.14±10.84 years, were included. The mean BMI was 25.53±3.40. Among them, 23 patients were smokers (32.8%), 41 had hypertension (58.6%), and 36 had hyperlipidemia (51.4%).
2. Patients in the CMD group had significantly shorter diabetes duration (6.59±2.18 years vs. 8.13±2.17 years) and lower glycosylated hemoglobin (7.99±1.52% vs. 8.78±1.55%) (P&lt;0.05). No significant differences were observed in other parameters.
3. GLS and ∆GLS differed significantly between groups, while other echocardiographic parameters did not.
4. Logistic regression analysis identified GLS as an independent predictor of CMD in diabetic patients under stress.

Conclusions
1. Diabetic patients with CMD exhibit lower GLS and ∆GLS under stress, indicating early reductions in left ventricular systolic function reserve.
2. 2D-STE can detect early left ventricular systolic impairment in diabetic patients.MCE quantitative analysisGLS in normal and CMD group