Threshold level of low-density lipoprotein cholesterol for the short-term benefit of statin therapy in the acute phase of myocardial infarction.

BACKGROUND: Little is known about the threshold level of low-density lipoprotein cholesterol (LDL-C) for statin therapy in acute myocardial infarction (AMI).

HYPOTHESIS: The aim of this study was to investigate the short-term benefit of the statin in post-MI patients with low LDL-C levels.

METHODS: Between November 2005 and January 2008, 6866 statin-naive patients were selected from the Korea AMI registry. Major adverse cardiac event (MACE) was defined as a composite of death, recurrent MI, and revascularizations.

RESULTS: The 6-month MACE and mortality showed a U-shaped curve, with the lowest rate at 114-122 mg/dL. Propensity scores for statin use were calculated for patients with LDL-C ≤ 113 mg/dL, and they were used to match the patients who received statin (statin user, n = 1031) with those who did not receive it (statin nonuser, n = 1031). The 6-month MACE was not significantly different between statin users and statin nonusers (9.4% vs 11.0%; hazard ratio [HR]: 0.847, 95% confidence interval [CI]: 0.646-1.111, P = 0.230), whereas the 6-month mortality was significantly lower in statin users (7.2% vs 9.7%; HR: 0.728, 95% CI: 0.539-0.984, P = 0.039). However, when the analyses were repeated in the patients with LDL-C ≤ 105 mg/dL, not only the 6-month MACE (9.5% vs 9.9%; HR: 0.945, 95% CI: 0.700-1.277, P = 0.713) but also the 6-month mortality (7.0% vs 8.7%; HR: 0.793, 95% CI: 0.566-1.111, P = 0.177) was not significantly different between statin users and statin nonusers (n = 876 in each group).

CONCLUSIONS: The beneficial effects of statin therapy seem to vanish when LDL-C is below a certain level in AMI patients.