BACKGROUND
Guidelines recommend nonstatin lipid-lowering agents in patients at very high risk for major adverse cardiovascular events (MACE) if low-density lipoprotein cholesterol (LDL-C) remains ≥70 mg/dL on maximum tolerated statin treatment. It is uncertain if this approach benefits patients with LDL-C near 70 mg/dL. Lipoprotein(a) levels may influence residual risk.
OBJECTIVES
In a post hoc analysis of the ODYSSEY Outcomes (Evaluation of Cardiovascular Outcomes After an Acute Coronary Syndrome During Treatment With Alirocumab) trial, the authors evaluated the benefit of adding the proprotein subtilisin/kexin type 9 inhibitor alirocumab to optimized statin treatment in patients with LDL-C levels near 70 mg/dL. Effects were evaluated according to concurrent lipoprotein(a) levels.
METHODS
ODYSSEY Outcomes compared alirocumab with placebo in 18,924 patients with recent acute coronary syndromes receiving optimized statin treatment. In 4,351 patients (23.0%), screening or randomization LDL-C was <70 mg/dL (median 69.4 mg/dL; interquartile range: 64.3–74.0 mg/dL); in 14,573 patients (77.0%), both determinations were ≥70 mg/dL (median 94.0 mg/dL; interquartile range: 83.2–111.0 mg/dL).
RESULTS
In the lower LDL-C subgroup, MACE rates were 4.2 and 3.1 per 100 patient-years among placebo-treated patients with baseline lipoprotein(a) greater than or less than or equal to the median (13.7 mg/dL). Corresponding adjusted treatment hazard ratios were 0.68 (95% confidence interval [Cl]: 0.52–0.90) and 1.11 (95% Cl: 0.83–1.49), with treatment-lipoprotein(a) interaction on MACE (
P
interaction
= 0.017). In the higher LDL-C subgroup, MACE rates were 4.7 and 3.8 per 100 patient-years among placebo-treated patients with lipoprotein(a) >13.7 mg/dL or ≤13.7 mg/dL; corresponding adjusted treatment hazard ratios were 0.82 (95% Cl: 0.72–0.92) and 0.89 (95% Cl: 0.75–1.06), with
P
interaction
= 0.43.
CONCLUSIONS
In patients with recent acute coronary syndromes and LDL-C near 70 mg/dL on optimized statin therapy, proprotein subtilisin/kexin type 9 inhibition provides incremental clinical benefit only when lipoprotein(a) concentration is at least mildly elevated. (ODYSSEY Outcomes: Evaluation of Cardiovascular Outcomes After an Acute Coronary Syndrome During Treatment With Alirocumab;
NCT01663402
)
Patients with high-risk AMI at hospitals without a catheterization laboratory may have an improved outcome when transferred for primary PTCA versus on-site thrombolysis; however, this will require further study. The marked delay in the transfer process suggests a role for triaging patients directly to specialized heart-attack centers.
Secretion of plasminogen activator inhibitor type-1 (PAI-1) by cultured cells is increased after exposure to specific cytokines and growth factors. We have shown previously that incubation of Hep G2 cells with epidermal growth factor (EGF) results in a marked increase in steady state levels of PAI-1 mRNA (Lucore, C.L., et al. (1988) J. Biol. Chem. 263, 15845-15848). The present study was undertaken to determine whether the regulation of expression of PAI-1 mRNA by EGF is mediated at the level of transcription and/or by post-transcriptional mechanisms. The rate of transcription of the PAI-1 gene measured by nuclear run-on assays was found to be increased within 2 h after stimulation of the cells with EGF (5 ng/ml) (3.2 fold increase relative to control, n = 2, range 3.0-3.4). It reached a maximum in 3 h, (9.2 fold increase relative to control, n = 2, range 8.8-9.6) and returned to baseline in 5 h. Exposure of the cells to EGF did not increase the rate of transcription of the glyceraldehyde-3-phosphate dehydrogenase gene. The half life of PAI-1 mRNA in Hep G2 cells was 120 min as determined by RNA blot analysis after exposure of the cells to actinomycin D to inhibit transcription. Stimulation of the cells with EGF did not result in significant change in the half life of PAI-1 mRNA. The results demonstrate that exposure of Hep G2 cells to EGF increases PAI-1 gene transcription.
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