Statins are a class of medications designed to manage high cholesterol levels. They work by reducing the production of low-density lipoprotein cholesterol (LDL-C), often called “bad cholesterol.” Lowering LDL-C is the main goal because high levels contribute to the buildup of plaque in arteries, increasing the risk of heart attack and stroke. The decision to begin this therapy is highly individualized and relies on a thorough assessment of a person’s overall risk for developing cardiovascular disease.
Calculating Cardiovascular Risk
The initial step in determining the need for statin therapy involves quantifying a person’s future risk of a cardiovascular event, especially for those who have not yet had one. Clinicians use a standardized tool called the Atherosclerotic Cardiovascular Disease (ASCVD) Risk Estimator, which is based on guidelines from major heart organizations. This calculator uses a specific set of clinical and personal variables to predict the likelihood of a heart attack or stroke within the next ten years.
The variables entered into the calculator include age, sex, race, and measurements of total and high-density lipoprotein (HDL) cholesterol. Additional information is gathered on systolic blood pressure and whether the patient is currently taking medication for hypertension. The assessment also accounts for the person’s history of smoking and their current diabetes status.
The resulting figure is a percentage that places the patient into one of several risk categories, such as low, borderline, intermediate, or high. This 10-year risk percentage is a crucial piece of information that guides the subsequent conversation about starting preventive medication.
Initiating Statins for Preventative Care
For individuals who have never experienced a cardiovascular event, the decision to start statin therapy is classified as primary prevention and centers on specific risk thresholds and conditions. One clear group recommended for immediate, high-intensity statin therapy are those with extremely high baseline LDL-C levels, defined as 190 milligrams per deciliter (mg/dL) or greater. This high level of cholesterol indicates a significant, inherent risk that requires aggressive intervention, regardless of the calculated 10-year ASCVD score.
Another group where statin therapy is generally recommended without needing the full risk calculation is adults aged 40 to 75 who have diabetes. For these patients, moderate-intensity statin therapy is typically indicated, even if their calculated 10-year ASCVD risk is low. If a person with diabetes also has multiple additional risk factors, a high-intensity statin may be prescribed to achieve a greater reduction in LDL-C.
The third and largest group are individuals aged 40 to 75 without diabetes or extremely high LDL-C, whose decision is based entirely on the calculated 10-year ASCVD risk. Patients who fall into the intermediate-risk category, with a score between 7.5% and less than 20%, are generally advised to have a discussion with their clinician about starting a moderate-intensity statin. This conversation includes reviewing risk-enhancing factors such as a strong family history of early heart disease or elevated inflammatory markers.
For those whose calculated risk is 20% or higher, the benefits of statin therapy become more pronounced. Clinical guidelines strongly recommend initiating statin therapy, often at a high-intensity dose, to achieve a significant reduction in LDL-C. The goal is to reduce the LDL-C level by 50% or more to substantially lower the probability of a future event.
Immediate Statin Use After a Cardiovascular Event
When a person has already experienced a cardiovascular event, the treatment strategy shifts to secondary prevention, and the decision to start statins becomes mandatory and immediate. The event itself confirms the presence of significant underlying atherosclerotic disease. The goal of therapy is to prevent a recurrence by stabilizing existing plaque and aggressively lowering cholesterol levels.
A cardiovascular event is defined as a history of:
- Myocardial infarction (heart attack)
- Ischemic stroke
- Transient ischemic attack (TIA)
- Stable or unstable angina
- Peripheral arterial disease (PAD)
For nearly all patients in this secondary prevention group, high-intensity statin therapy is recommended immediately. This high level of treatment is crucial because a lower LDL-C is directly correlated with a greater reduction in the risk of another event.
The initiation of statin therapy is generally not dependent on the person’s current LDL-C measurement because the proven risk is already so high. The standard target for reduction is often a 50% or greater decrease in LDL-C from baseline. For very high-risk patients, the goal may be to reach a specific LDL-C threshold, such as below 70 mg/dL, sometimes requiring the addition of non-statin medications if the statin alone is insufficient.
Medical Conditions That Preclude Statin Use
There are specific medical circumstances where starting statin medication is either strongly discouraged or absolutely contraindicated. The most definitive contraindications are for women who are pregnant or are currently breastfeeding. Statins should not be taken during pregnancy or lactation due to the lack of clear evidence on their safety for the developing fetus or infant.
Another absolute contraindication is the presence of active or acute liver disease. Statins are metabolized in the liver, and their use could potentially worsen existing liver inflammation or damage. Clinicians typically check baseline liver enzyme levels before initiating therapy to ensure the liver is functioning properly.
Extreme caution is required when prescribing statins for patients with severe kidney impairment or those taking certain other medications. Some statins are known to interact with drugs such as cyclosporine, specific antifungals, or certain HIV protease inhibitors, which can raise the concentration of the statin in the blood and increase the risk of serious side effects. Patients who consume large quantities of alcohol are also at higher risk and require careful monitoring.