# Preventive Cardiology and Lipid Management

## Atherosclerotic Cardiovascular Disease Risk Assessment

### Pooled Cohort Equations (PCE)

The Pooled Cohort Equations provide the foundation for estimating 10-year atherosclerotic cardiovascular disease risk, encompassing myocardial infarction and stroke, in adults aged 40 to 79 years without established atherosclerotic cardiovascular disease. The model incorporates age, sex, race categorized as White or African American, total cholesterol, high-density lipoprotein cholesterol, systolic blood pressure, blood pressure treatment status, diabetes, and smoking status. Risk categories are stratified as low at less than 5%, borderline at 5 to 7.4%, intermediate at 7.5 to 19.9%, and high at 20% or greater. Important limitations of the equations include potential overestimation of risk in certain populations such as Asian and Hispanic individuals, and the absence of variables for family history, inflammatory markers, and coronary calcium.

### Risk Enhancers (Favor Statin Therapy in Borderline/Intermediate Risk)

Multiple risk-enhancing factors support the decision to initiate statin therapy in patients at borderline or intermediate risk. A family history of premature atherosclerotic cardiovascular disease in a first-degree male relative before age 55 or female relative before age 65 is among the most important. Persistently elevated low-density lipoprotein cholesterol of 160 mg/dL or greater, metabolic syndrome, chronic kidney disease with an estimated glomerular filtration rate below 60, and chronic inflammatory conditions including systemic lupus erythematosus, rheumatoid arthritis, psoriasis, and HIV all enhance risk assessment. South Asian ancestry carries additional risk. Persistently elevated triglycerides of 175 mg/dL or greater, a high-sensitivity C-reactive protein of 2 mg/L or greater, and an ankle-brachial index below 0.9 are additional risk enhancers.

Lipoprotein(a) at 50 mg/dL or greater, equivalent to 125 nmol/L or greater, represents an independent, genetically determined risk factor that is not lowered by statin therapy and should be measured at least once during a patient's lifetime. An apolipoprotein B of 130 mg/dL or greater provides additional risk information particularly when low-density lipoprotein cholesterol may be discordantly low relative to atherogenic particle burden.

### Coronary Artery Calcium (CAC) Scoring

Coronary artery calcium scoring has its strongest indication in intermediate-risk patients with a 10-year risk of 7.5 to 19.9%, where the statin therapy decision remains uncertain after clinical risk assessment. A calcium score of zero indicates a very low event rate of less than 1% over 10 years, making it reasonable to defer statin therapy in the absence of diabetes, active smoking, or a strong family history. Scores of 1 to 99 indicate moderate risk favoring statin initiation, while scores of 100 to 299 strongly support statin therapy. A score of 300 or greater, or a score at or above the 75th percentile for age and sex, indicates high risk with a strong recommendation for statin therapy. Data from the Multi-Ethnic Study of Atherosclerosis demonstrated that coronary artery calcium scoring improves risk reclassification beyond traditional risk factors, with a net reclassification improvement of 25 to 30% in intermediate-risk patients.

## Lipid-Lowering Therapy

### Statin Intensity Classification

| Intensity | LDL-C Reduction | Agents |
|---|---|---|
| High (>=50% reduction) | >=50% | Atorvastatin 40-80 mg; Rosuvastatin 20-40 mg |
| Moderate (30-49%) | 30-49% | Atorvastatin 10-20 mg; Rosuvastatin 5-10 mg; Simvastatin 20-40 mg; Pravastatin 40 mg |
| Low (<30%) | <30% | Simvastatin 10 mg; Pravastatin 10-20 mg; Lovastatin 20 mg |

### Non-Statin Lipid-Lowering Agents

| Agent | Mechanism | LDL-C Reduction | Key Trial | Notes |
|---|---|---|---|---|
| Ezetimibe | NPC1L1 transporter blockade | 15-20% | IMPROVE-IT (NNT 50 over 7 yrs, post-ACS) | First-line add-on to statin |
| Evolocumab (PCSK9i) | PCSK9 monoclonal antibody | ~59% | FOURIER: 15% MACE reduction; 27% MI reduction | SC q2 weeks |
| Alirocumab (PCSK9i) | PCSK9 monoclonal antibody | ~63% | ODYSSEY: 15% MACE reduction; mortality signal in high-LDL tertile | SC q2 weeks |
| Inclisiran (siRNA) | Hepatic PCSK9 synthesis silencing | ~50% | ORION trials (no CV outcomes trial yet) | SC q6 months after loading |
| Bempedoic acid | ATP citrate lyase inhibitor | ~20% | CLEAR Outcomes: 13% MACE reduction (statin-intolerant) | No myalgia (not activated in skeletal muscle) |
| Icosapent ethyl (EPA) | Purified EPA; anti-inflammatory + TG reduction | TG: 18% | REDUCE-IT: 25% MACE reduction (NNT 21) | For TG 135-499 on statin |

### Statin Therapy

Statin therapy is classified by intensity of low-density lipoprotein cholesterol reduction. High-intensity statins, including atorvastatin 40 to 80 mg and rosuvastatin 20 to 40 mg, reduce low-density lipoprotein cholesterol by 50% or more. Moderate-intensity options include atorvastatin 10 to 20 mg, rosuvastatin 5 to 10 mg, simvastatin 20 to 40 mg, and pravastatin 40 mg, achieving 30 to 49% reductions. Low-intensity statins, including simvastatin 10 mg, pravastatin 10 to 20 mg, and lovastatin 20 mg, provide less than 30% reduction and have limited indications.

### Statin Indications by Category

Four primary clinical categories guide statin prescribing. In patients with established clinical atherosclerotic cardiovascular disease for secondary prevention, high-intensity statin therapy is recommended for all patients aged 75 years or younger, with consideration in those over 75 based on individual risk-benefit assessment. Patients with low-density lipoprotein cholesterol of 190 mg/dL or greater, suggesting an underlying genetic dyslipidemia, warrant high-intensity statin therapy without the need for risk calculator assessment. All patients with diabetes mellitus aged 40 to 75 should receive at least moderate-intensity statin therapy, escalated to high-intensity when the 10-year risk is 7.5% or greater or multiple risk enhancers are present. In the primary prevention population aged 40 to 75 with low-density lipoprotein cholesterol of 70 to 189 mg/dL and a 10-year risk of 7.5% or greater, moderate-to-high-intensity statin therapy is recommended after a shared risk discussion.

### LDL-C Targets

The ACC/AHA 2018 guidelines employ thresholds for therapy escalation rather than strict numerical targets. For very high-risk atherosclerotic cardiovascular disease, defined by recent acute coronary syndrome, multiple cardiovascular events, multivessel coronary artery disease, or the combination of peripheral arterial disease with diabetes and smoking, a low-density lipoprotein cholesterol threshold below 70 mg/dL is used, with ezetimibe added if not at goal and a PCSK9 inhibitor added if the threshold is still not achieved on maximally tolerated statin plus ezetimibe. The 2019 ESC/EAS guidelines adopt more aggressive strict targets: less than 55 mg/dL with at least a 50% reduction from baseline for very high-risk patients, less than 70 mg/dL with at least a 50% reduction for high-risk, less than 100 mg/dL for moderate risk, and less than 116 mg/dL for lower risk.

### Statin Safety and Side Effects

Myalgias represent the most commonly reported statin side effect, occurring in 5 to 10% of patients in clinical trials but at higher rates of 10 to 20% in clinical practice. True statin intolerance, confirmed by rechallenge and crossover methodology, affects only approximately 5 to 7% of patients. The SAMSON trial demonstrated that 90% of statin-attributed symptoms were from the nocebo effect. Rhabdomyolysis is rare at less than 0.01%, with risk increased by drug interactions involving CYP3A4 inhibitors affecting simvastatin, atorvastatin, and lovastatin metabolism. New-onset diabetes carries a relative risk increase of approximately 10 to 12%, with a number needed to harm of approximately 250 over 4 years, though the net cardiovascular benefit far exceeds the diabetes risk. Hepatotoxicity with alanine aminotransferase elevation exceeding 3 times the upper limit of normal occurs in less than 1%, with clinically significant liver injury extremely rare. Baseline liver function tests are recommended, but routine monitoring is not required unless symptoms develop. No proven causal relationship with cognitive impairment has been established, with the EBBINGHAUS trial conducted alongside the FOURIER PCSK9 inhibitor trial finding no cognitive decline. Management of statin intolerance includes dose reduction, alternate-day dosing with rosuvastatin or atorvastatin given their long half-lives, switching to a different statin, or adding non-statin therapy if no statin is tolerated.

### Ezetimibe

Ezetimibe blocks the NPC1L1 cholesterol transporter in the small intestine, reducing low-density lipoprotein cholesterol by 15 to 20%. The IMPROVE-IT trial demonstrated that adding ezetimibe to simvastatin reduced cardiovascular events compared to simvastatin alone in post-acute coronary syndrome patients, achieving a low-density lipoprotein cholesterol of 54 mg/dL with a number needed to treat of 50 over 7 years. Ezetimibe at 10 mg daily is the first-line add-on to statin therapy when low-density lipoprotein cholesterol goals are not met and is well tolerated.

### PCSK9 Inhibitors

PCSK9 inhibitors represent a major advance in lipid-lowering therapy. Evolocumab (Repatha) was evaluated in the FOURIER trial, which demonstrated a 59% reduction in low-density lipoprotein cholesterol to a median of 30 mg/dL, a 15% reduction in the primary cardiovascular composite endpoint, a 27% reduction in myocardial infarction, and a 21% reduction in stroke, though no mortality benefit was observed at 2.2 years. Alirocumab (Praluent) was evaluated in the ODYSSEY Outcomes trial in post-acute coronary syndrome patients, showing a 63% reduction in low-density lipoprotein cholesterol, a 15% reduction in major adverse cardiovascular events, and a signal for mortality benefit in the highest baseline low-density lipoprotein cholesterol tertile of 100 mg/dL or greater.

Inclisiran (Leqvio) represents a distinct approach using small interfering RNA technology targeting hepatic PCSK9 synthesis, administered as a subcutaneous injection twice yearly after two loading doses. The ORION trials demonstrated approximately 50% low-density lipoprotein cholesterol reduction with a durable effect, though the drug has not yet been powered for a cardiovascular outcomes trial. Indications for PCSK9 inhibitors include atherosclerotic cardiovascular disease patients not at low-density lipoprotein cholesterol goal despite maximally tolerated statin plus ezetimibe, familial hypercholesterolemia with low-density lipoprotein cholesterol of 100 mg/dL or greater, and statin-intolerant patients with high cardiovascular risk.

### Bempedoic Acid

Bempedoic acid inhibits ATP citrate lyase, reducing cholesterol synthesis upstream of HMG-CoA reductase, and is dosed at 180 mg daily. The CLEAR Outcomes trial demonstrated a 13% reduction in major adverse cardiovascular events in statin-intolerant patients, with an approximately 20% reduction in low-density lipoprotein cholesterol. A key advantage is the absence of myalgia, as bempedoic acid is a prodrug that is not activated in skeletal muscle. Potential side effects include hyperuricemia and a low incidence of tendon rupture. It is available as a combination pill with ezetimibe (Nexlizet).

<image>
A stepped lipid-lowering treatment algorithm for patients with ASCVD. Start with "Established ASCVD" at top. Step 1: "Maximally tolerated high-intensity statin (atorvastatin 80mg or rosuvastatin 40mg)." Arrow down with LDL-C check at 4-6 weeks. Decision: "LDL-C >= 70 mg/dL (ACC/AHA) or >= 55 mg/dL (ESC for very high risk)?" If yes → Step 2: "Add ezetimibe 10 mg." Arrow down with LDL-C check. Still above goal? → Step 3: "Add PCSK9 inhibitor (evolocumab 140mg SC q2wk or alirocumab 75-150mg SC q2wk) OR inclisiran 284mg SC q6months." Side pathway for statin-intolerant patients: "Bempedoic acid 180mg + ezetimibe 10mg ± PCSK9 inhibitor." Bottom box: "Additional considerations for residual risk: elevated TG (>= 150): icosapent ethyl 2g BID if TG 135-499; elevated Lp(a): awaiting olpasiran/muvalaplin trials; elevated hsCRP: consider colchicine 0.5mg daily." Show target LDL values in green boxes: <70 mg/dL (ACC/AHA) and <55 mg/dL (ESC very high risk). Each step should show expected LDL reduction percentage.
</image>

## Triglyceride Management

### Severe Hypertriglyceridemia (TG >= 500 mg/dL)

The primary goal when triglycerides reach 500 mg/dL or higher is prevention of acute pancreatitis. Fibrates serve as first-line therapy, with fenofibrate at 145 mg daily or gemfibrozil at 600 mg twice daily reducing triglycerides by 30 to 50%. When combining with statins, fenofibrate is preferred because gemfibrozil inhibits statin glucuronidation, significantly increasing the risk of myopathy. Prescription-grade omega-3 fatty acids at high doses of 4 grams daily of combined EPA and DHA reduce triglycerides by 25 to 35%. Dietary measures include adoption of a very low-fat diet with less than 15% of calories from fat and avoidance of alcohol and refined carbohydrates. Genetic causes such as familial chylomicronemia syndrome and familial hypertriglyceridemia should be considered in patients with severely elevated levels.

### Moderate Hypertriglyceridemia (TG 150-499 mg/dL) with ASCVD

The REDUCE-IT trial established that icosapent ethyl (Vascepa), a purified eicosapentaenoic acid formulation, at 2 grams twice daily in patients with triglycerides of 135 to 499 mg/dL on statin therapy reduced major adverse cardiovascular events by 25%, with a number needed to treat of 21 over 5 years. The mechanism likely extends beyond the modest 18% triglyceride reduction, encompassing anti-inflammatory, membrane-stabilizing, and anti-thrombotic effects. The STRENGTH trial, which used a combined EPA and DHA formulation, showed no benefit, suggesting an EPA-specific effect rather than a general omega-3 benefit. Controversy surrounds the mineral oil placebo used in REDUCE-IT, which may have increased LDL cholesterol and C-reactive protein in the control arm, potentially inflating the apparent benefit. Current recommendations support icosapent ethyl at 2 grams twice daily for patients with atherosclerotic cardiovascular disease or diabetes and triglycerides of 135 to 499 mg/dL despite statin therapy, carrying a Class IIa recommendation in the 2019 ACC/AHA focused update.

## Lipoprotein(a)

### Clinical Significance

Lipoprotein(a) is a genetically determined lipoprotein whose levels are not significantly altered by diet, exercise, or statin therapy. It has been established as an independent causal risk factor for both atherosclerotic cardiovascular disease and calcific aortic stenosis. Levels at or above 50 mg/dL, equivalent to 125 nmol/L, are associated with a 2 to 3-fold increased risk of atherosclerotic cardiovascular disease. Elevated lipoprotein(a) affects 20 to 25% of the general population, with disproportionate prevalence in African American and South Asian populations. Current guidelines recommend measuring lipoprotein(a) at least once per lifetime for all adults, with earlier measurement for those with a family history of premature atherosclerotic cardiovascular disease or personal atherosclerotic disease.

### Emerging Therapies

Several therapeutic strategies for lowering lipoprotein(a) are in advanced development. Olpasiran, a small interfering RNA targeting hepatic lipoprotein(a) synthesis, achieved a 97% reduction in lipoprotein(a) with subcutaneous injection every 12 weeks in the OCEAN(a)-DOSE trial, with the OCEAN(a)-Outcomes cardiovascular outcomes trial ongoing. Muvalaplin, an oral small molecule that blocks lipoprotein(a) assembly, has demonstrated 60 to 70% lipoprotein(a) reduction in Phase 2 data. Pelacarsen, an antisense oligonucleotide, achieves approximately 80% lipoprotein(a) reduction and is being evaluated in the Lp(a)HORIZON outcomes trial. Currently, no approved lipoprotein(a)-lowering therapy exists, and management of residual risk in patients with elevated lipoprotein(a) focuses on intensifying low-density lipoprotein cholesterol lowering and addressing other modifiable risk factors.

## Anti-Inflammatory Therapy

### Colchicine

Colchicine has emerged as the first anti-inflammatory therapy with proven cardiovascular event reduction in atherosclerotic disease. The COLCOT trial demonstrated that colchicine at 0.5 mg daily initiated after acute coronary syndrome reduced the primary composite of cardiovascular death, myocardial infarction, stroke, coronary revascularization, and hospitalization for unstable angina by 23%. The LoDoCo2 trial confirmed these findings in chronic coronary disease, showing a 31% reduction in cardiovascular events. The 2023 ACC/AHA guidelines state that colchicine 0.5 mg daily may be considered for secondary prevention of atherosclerotic cardiovascular disease, carrying a Class IIb recommendation. Side effects include gastrointestinal symptoms such as diarrhea and nausea, and monitoring of complete blood count and renal function is required. The drug should be avoided in severe chronic kidney disease and hepatic impairment, with attention to drug interactions involving CYP3A4 inhibitors and P-glycoprotein inhibitors.

### CANTOS (Canakinumab)

The CANTOS trial represented a landmark proof-of-concept study demonstrating that targeting inflammation with canakinumab, an anti-interleukin-1beta monoclonal antibody, reduced high-sensitivity C-reactive protein and cardiovascular events by 15%. However, an increase in fatal infections was observed, and the drug was not commercially developed for the atherosclerotic cardiovascular disease indication. The trial's enduring significance lies in its validation of the inflammatory hypothesis of atherosclerosis.

## Hypertension Management in CV Prevention

### Targets (2017 ACC/AHA)

The 2017 ACC/AHA hypertension guidelines established a blood pressure target of less than 130/80 mmHg for the general population. For high-risk patients, the SPRINT trial demonstrated that intensive targeting to below 120 mmHg systolic reduced major adverse cardiovascular events by 25% and mortality by 27% compared to the standard target of below 140 mmHg, though the trial excluded diabetic patients. The SPRINT-CKD subgroup confirmed benefit in patients with chronic kidney disease with a target below 120 mmHg systolic. For elderly patients aged 65 and above, targeting below 130 mmHg systolic is recommended if tolerated, with attention to balancing fall risk and hypotension.

### First-Line Agents

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers are preferred in patients with diabetes, chronic kidney disease with proteinuria, heart failure, and post-myocardial infarction. Thiazide diuretics, with chlorthalidone at 12.5 to 25 mg preferred over hydrochlorothiazide for its longer duration of action and stronger outcomes data, represent another first-line option. Calcium channel blockers including amlodipine and nifedipine extended-release are effective, well-tolerated, and preferred alongside thiazide diuretics in African American patients.

## Key Clinical Pearls

- CAC scoring is the most powerful tool for reclassifying intermediate-risk patients -- a CAC of 0 gives a "warranty period" of ~5-10 years of very low risk and may allow deferral of statin therapy; CAC >= 100 strongly favors statin initiation
- PCSK9 inhibitors can achieve LDL-C levels as low as 10-20 mg/dL with no evidence of harm at these levels -- "lower is better" has no identified lower bound for LDL-C safety
- Measure Lp(a) at least once in every patient with established ASCVD or family history of premature ASCVD -- it is the most common inherited lipid risk factor and will have targeted therapies within the next few years
- Statin intolerance is real but overdiagnosed -- SAMSON trial showed that 90% of statin-attributed symptoms were from the nocebo effect; rechallenge with a different statin at lower dose is successful in most patients
- Icosapent ethyl (purified EPA) reduces CV events by 25% in patients with elevated TG on statin therapy -- this is a larger relative risk reduction than adding ezetimibe or a PCSK9 inhibitor, yet remains underutilized
- Colchicine 0.5 mg daily is the first anti-inflammatory therapy with proven CV event reduction in chronic coronary disease -- COLCOT and LoDoCo2 provide complementary evidence for its role in secondary prevention

## References

- Grundy SM, et al. 2018 AHA/ACC Guideline on the Management of Blood Cholesterol. Circulation. 2019;139:e1082-e1143.
- Sabatine MS, et al. Evolocumab and Clinical Outcomes in Patients with Cardiovascular Disease (FOURIER). NEJM. 2017;376:1713-1722.
- Bhatt DL, et al. Cardiovascular Risk Reduction with Icosapent Ethyl for Hypertriglyceridemia (REDUCE-IT). NEJM. 2019;380:11-22.
- Tardif JC, et al. Efficacy and Safety of Low-Dose Colchicine After Myocardial Infarction (COLCOT). NEJM. 2019;381:2497-2505.
- Nissen SE, et al. Bempedoic Acid in Statin-Intolerant Patients (CLEAR Outcomes). NEJM. 2023;388:1353-1364.