The multivariate analysis (Table 4) shows that among young patients, a higher risk of myocardial infarction was related to gender, hypertension, hypercholesterolemia, myocardial infarction in first-degree relatives, carrier state of allele G of PECAM1 373C/G, interaction between the carrier state of allele T of MMP9 −1562C/T and hypertension, interaction between the carrier state of allele A of PECAM1 G1688A and first-degree relatives. Here, MMP9 is linked to myocardial infarction.