A Plant-Based Diet in the Treatment of Coronary Microvascular Dysfunction

Change in Brachial Artery Flow-Mediated Dilation (FMD)

Brachial artery flow-mediated dilation (FMD) will be assessed by ultrasound and reported as the percentage increase in brachial artery diameter from the resting pre-occlusion diameter to the peak post-occlusion diameter. FMD is a continuous physiological measurement. Higher FMD percentages indicate greater endothelium-dependent vasodilation and better peripheral endothelial function. Change from baseline will be calculated as the FMD percentage at each post-baseline visit minus the baseline FMD percentage and reported in percentage points.

Change in Cutaneous Microvascular Function

Cutaneous microvascular function will be assessed using laser Doppler flowmetry during standardized local heating. Mean cutaneous vascular conductance during the stable local-heating plateau will be calculated by dividing laser Doppler flux by concurrently measured mean arterial pressure and reported in perfusion units per millimeter of mercury (PU/mmHg). Cutaneous vascular conductance is a continuous physiological measurement. Higher values during local heating indicate greater cutaneous microvascular vasodilatory responsiveness. Change from baseline will be calculated as the value at each post-baseline visit minus the baseline value.

Change in Digital Endothelial Function

Digital endothelial function will be assessed using peripheral arterial tonometry and reported as the Reactive Hyperemia Index (RHI). RHI is a continuous, dimensionless physiological index derived from the post-occlusion digital pulse-amplitude response and normalized to the control finger. RHI has no fixed minimum or maximum. Higher RHI values indicate better digital endothelial function. Change from baseline will be calculated as the value at each post-baseline visit minus the baseline value.

Change in Central Arterial Stiffness

Central arterial stiffness assessed by carotid-femoral pulse wave velocity (PWV) using the SphygmoCor system. Pulse wave velocity will be analyzed in meters per second, with lower values reflecting lower arterial stiffness.

Change in Systemic Redox Status

Plasma aminothiol redox status measured by concentrations of reduced and oxidized aminothiol species, including cysteine, cystine, glutathione, and glutathione disulfide.

Percentage of Prescribed Study Foods Consumed Assessed by ASA24 Dietary Recalls

Dietary adherence will be quantified using repeated Automated Self-Administered 24-Hour Dietary Assessment Tool (ASA24) recalls. Adherence will be calculated as the proportion of prescribed study foods reported as consumed relative to the foods assigned, expressed as a percentage. Possible values range from 0% to 100%, with higher percentages indicating greater adherence. Average adherence of at least 85% will define adherence for sensitivity analyses.

Number of Participants With Animal-Food DNA Detected by FoodSEQ

FoodSEQ will be performed on a randomly selected subset of stool specimens to determine whether animal-food-derived DNA is detected. The outcome will be reported as the number of participants with animal-food-derived DNA detected in at least one evaluable specimen. A lower number indicates greater biological corroboration of adherence to the prescribed plant-based diet.

Number of Participants Who Complete the 12-Week Intervention

The outcome will be reported as the number of enrolled participants who remain in the study through the end of the 12-week dietary intervention and complete the Week 12 assessment. Participants who withdraw before completing the intervention will not be counted as completers.