Adherence to the Mediterranean Diet and Its Association with LDL-Cholesterol and Subendocardial Viability Ratio in Individuals with Familial Hypercholesterolemia: A Cross-Sectional Study

Background/Objectives: An intensive lipid-lowering therapy is needed in familial hypercholesterolemia (FH) subjects; however, the adherence to the Mediterranean diet (MD) and its effects have not been fully evaluated in FH subjects. This study aimed to evaluate the impact of the MD on metabolic and vascular profiles in FH subjects. Methods: In this cross-sectional study 253 genetically confirmed FH subjects were included. Adherence to MD was assessed by the validated Pyramid-based MD Score (PyrMDS) and FH subjects were stratified according to the tertiles of PyrMDSs (low, intermediate, and high), with a higher score indicating higher adherence to MD. The lipid profile as well as the subendocardial viability ratio (SEVR), an indirect measure of myocardial perfusion, were assessed in all FH subjects. Results: Compared to the low-PyrMDS group, FH subjects with a high MD adherence showed lower levels of low-density lipoprotein cholesterol (LDL-C) (149.7 ± 71.4 vs. 176.7 ± 77.4 mg/dL, p = 0.006). After accounting for lipid-lowering therapies, smoking habit, and arterial hypertension, individuals in the high-PyrMDS group showed higher SEVR than those in the intermediate- and low-PyrMDS groups (167 ± 3.51 standard error—SE vs. 150 ± 5.03 SE vs. 148 ± 3.75 SE, all p < 0.01). After adjusting for age, sex, and lipid-lowering therapies, PyrMDS was independently associated with LDL-C (β = −0.11, p = 0.03). Conclusions: Greater adherence to the MD was associated with more favorable metabolic and vascular profiles in FH subjects independent of lipid-lowering therapies. This suggests that MD adherence should be actively promoted in clinical practice alongside pharmacological interventions.