The European Society of Cardiology recommends treatment for people with ischemic heart disease (IHD) to achieve low-density lipoprotein cholesterol (LDL-C) levels below 70 mg/dL, but the American Heart Association has no recommendations on LDL-C levels. This discrepancy directed scientists to explore further the effect of LDL-C levels and the cholesterol-lowering statins on patients with IHD, the subject of a study recently published in JAMA Internal Medicine.
Statins lower cholesterol levels when diet and exercise can’t do the job, and they work by disrupting the initial production of cholesterol that occurs in the liver. The new study of over 30 thousand patients with pre-existing IHD attempted to answer why statins lower the risk for a major adverse cardiac event (MACE) for some patients and not for others.
LDL-C is often known as the “bad” kind of cholesterol, and it lives up to its notoriety by building up in the arteries at elevated levels, increasing the risk for atherosclerosis, a buildup of plaque in the blood vessels. LDL-C levels are most likely to be elevated in a person who maintains a diet high in saturated and trans fats.
Researchers looked at 31,619 with preexisting IHD and at least 80 percent “adherent” to statin treatment. Each patient in the study had been receiving statin treatment for at least one year.
Approximately 30 percent of the patients presented with low levels of LDL-C, considered to be 70 mg/dL or lower, 50 percent with moderate levels (70.1 – 100 mg/dL), and 20 percent high levels (100.1 – 130 mg/dL). After an average 1.6 years of follow-up time, 9,035 patients either had a MACE or died. Researchers consider a MACE to be one of the following events:
- heart attack
- unstable angina
While the resarchers did not find low levels of LDL-C to be significantly associated with an elevated risk of a MACE as compared to patients with moderate LDL-C levels, they did find a significant reduction in risk for patients with moderate levels of LDL-C as compared to patients with high LDL-C levels.
The researchers from the study are hesitant to apply their results to a wide variety of IHD cases until further studies can be completed. "Our results do not provide support for a blanket principle that lower LDL-C is better for all patients in secondary prevention," they decided.
Regardless, most patients with stable IHD are recommended by doctors to receive long-term treatment with statins to reduce their risk of “recurring cardiovascular events.”
Sources: The JAMA Network Journals
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