Abstract only Introduction: Microvascular circulation controls tissue perfusion. Its dysfunction is implicated in damage to the myocardium and is a predictor of cardiovascular events. It has been shown that short-term dietary interventions may influence microvascular endothelial function (MEF) in some populations. There is a lack of evidence on the long-term effect of healthy diet patterns on MEF in patients with coronary heart disease (CHD) and on whether this effect is modified by the risk of CHD recurrence. Hypothesis: the consumption of healthy diets (Mediterranean diet or Low-fat diet) improves the MEF of CHD patients in the long term, and this effect is interrelated with the risk of CHD recurrence. Methods: In the CORDIOPREV study, dietary intervention with a Mediterranean diet or a low-fat diet is being carried out in 1002 patients with CHD for 7 years. The effect of this dietary intervention on basal microvascular flow and the area of hyperemia reactive to hypoxia was evaluated in 664 patients by laser-Doppler flowmetry at baseline and after 6 years of intervention. The risk of recurrence of CHD in patients was evaluated according to the TRS2P risk score. Results: Basal flow and reactive hyperemia area improved after the dietary intervention in the population (basal flow 97.78 ± 2.79 vs. 179.31 ± 5.06 arbitrary perfusion units, 83.38% increase, p<0.001) (reactive hyperemia 4233.3 ± 127.73 vs. 9695.9 ± 205.23 arbitrary perfusion units per time, 129.04% increase, p<0.001), without finding differences due to the diet (p>0.05 for the diet-effect). When patients were stratified to low, medium or high risk of recurrence, the basal flow was similarly increased in all three groups, but the reactive hyperemia area was improved to a greater extent in patients in the low-risk group compared with those in the medium or high risk groups. Conclusion: Long-term consumption of a healthy dietary pattern improves MEF in patients with CHD, and this improvement is greater in patients in the low-risk category for cardiovascular recurrence compared with those in the medium and high-risk groups.