We hypothesized that a short-course high-intensity statin treatment during admission for myocardial infarction (MI) could rapidly reduce LDL-C and thus impact the choice of lipid-lowering therapy (LLT) at discharge. Our cohort comprised 133 MI patients (62.71 ± 11.3 years, 82% male) treated with atorvastatin 80 mg o.d. during admission. Basal LDL-C levels before admission were analyzed. We compared lipid profile variables before and during admission, and LLT at discharge was registered. Achieved theoretical LDL-C levels were estimated using LDL-C during admission and basal LDL-C as references and compared to LDL-C on first blood sample 4–6 weeks after discharge. A significant reduction in cholesterol from basal levels was noted during admission, including total cholesterol, triglycerides, HDL-C, non-HDL-C, and LDL-C (−39.23 ± 34.89 mg/dL, p < 0.001). LDL-C levels were reduced by 30% in days 1–2 and 40–45% in subsequent days (R2 0.766, p < 0.001). Using LDL-C during admission as a reference, most patients (88.7%) would theoretically achieve an LDL-C < 55 mg/dL with discharge LLT. However, if basal LDL-C levels were considered as a reference, only a small proportion of patients (30.1%) would achieve this lipid target, aligned with the proportion of patients with LDL-C < 55 mg/dL 4–6 weeks after discharge (36.8%). We conclude that statin treatment during admission for MI can induce a significant reduction in LDL-C and LLT at discharge is usually prescribed using LDL-C during admission as the reference, which leads to insufficient LDL-C reduction after discharge. Basal LDL-C before admission should be considered as the reference value for tailored LLT prescription.