Several factors [20–22] might underlie HPR on clopidogrel including patient noncompliance, intestinal absorption (ABCB1 gene polymorphism), polymorphisms in CYP2C19, drug-drug interactions (e.g. omeprazole, β-Blockers [23]), and other clinical factors (age, BMI, diabetes, chronic renal insufficiency, heart failure). This evidence concerns the gene CYP2C19 and heart failure.