Blood Pressure Measurement and Monitoring

Blood Pressure Measurement

• Manual blood pressure cuffs need to be calibrated, and human interpretation can introduce errors.
• Automated blood pressure machines can have varying fidelity, validateBP.org can be used to check the fidelity.
• Correct cuff size is essential for accurate blood pressure readings:
  • A cuff too small will lead to a falsely high reading.
• Avoid caffeine, smoking, or exercising within 30 minutes of taking blood pressure.
• Do not talk during the reading.
• The cuff should cover 80% of the upper arm, with its bladder being ~40% of the arm circumference.

Home Blood Pressure Monitoring

• Automated blood pressure machines make at-home monitoring easier.
• Home measurements are more closely related to left ventricular mass than in-clinic measurements.
• CPT codes 99473 and 99474 are used for interpretation of out-of-office BP readings.
• Home BP readings are generally lower than office readings.
• Nighttime readings are more accessible with ambulatory 24-hour monitoring.
• Nocturnal BP readings have stronger predictive power for cardiovascular events.

Wrist Cuffs

• Radial systolic BP is generally 5.5 mm Hg higher than brachial systolic BP, with >20% of individuals having a difference of >10 mm Hg.
• Currently, there's no validation procedure to translate radial BP to brachial BP.
• At-home measurement using wrist BP cuffs can be unreliable.

Choosing a Treatment Target

• The first step for treating hypertension is choosing a blood pressure target.
• For most patients, including those with high cardiovascular risk, the target should be <130/80 mm Hg.
• If a patient doesn't respond to the maximum dose of a single medication, add another agent.
• Combining medications with different mechanisms of action is more effective in lowering BP.
• Maxing out on single medications can lead to more side effects without achieving the BP goal.

Diuretics

• Hydrochlorothiazide (HCTZ) is a commonly used first-line diuretic, well tolerated.
• HCTZ inhibits sodium and chloride reabsorption in the distal convoluted tubule, leading to decreased blood volume, sodium, potassium, and magnesium, resulting in reduced peripheral vascular resistance (PVR).
• Chlorthalidone (thiazide-like) is useful when HCTZ isn't achieving the goal, as it's more potent and has a longer half-life.
• Monitor potassium levels closely, especially with initiation.
• Lasix isn't a first-line antihypertensive diuretic for patients with intact renal function.

Calcium Channel Blockers (CCBs)

• CCBs are modest negative inotropes, reducing contractility of the heart.
• Commonly used CCBs include:
  • Amlodipine
  • Diltiazem
  • Verapamil
• Red Flags: Contraindicated in heart failure (HF), renal or hepatic impairment.

Beta-Adrenergic Antagonists

• Beta-blockers commonly used for hypertension:
  • Atenolol
  • Metoprolol
  • Carvedilol
  • Labetalol
  • Bisoprolol
  • Propranolol
• Block beta-1 adrenergic receptor sites, blunting catecholamine response.
• This decreases cardiac output and sympathetic outflow.
• Commonly used for post-myocardial infarction patients.
• Carvedilol and labetalol block beta-1, beta-2, and alpha-1 receptors, decreasing heart rate, stroke volume, and PVR.
• Non-cardioselective agents (beta-1 & beta-2) include propranolol and nadolol.
• Avoid non-cardioselective agents in asthma, COPD, pulmonary lung disease, and peripheral artery disease (PAD).
• Red Flags: Sinus bradycardia, depression, HF decompensation. Avoid abrupt cessation.

Aldosterone Antagonists

• Aldosterone antagonists commonly used for hypertension:
  • Spironolactone
  • Eplerenone
• Useful for hypertension resistance or primary aldosteronism.
• Consider spironolactone for a higher dose (150-300mg).
• Spironolactone has an androgen-blocking effect.
• Red Flags: Risk of hyperkalemia.

Statins

• Atorvastatin and rosuvastatin have longer half-lives and higher bioavailability.
• Diltiazem and grapefruit juice are 3A4 inhibitors, which can interact with some statins.

Association vs. Causation

• Emphasize diet and lifestyle modifications to avoid type 2 diabetes progression.
• Consider the risk-benefit ratio when making treatment decisions.

Ezetimibe (Zetia)

• Ezetimibe can further lower LDL cholesterol by about 17% on top of statin therapy.
• It's a selective cholesterol absorption inhibitor.
• Anticipated LDL-C reduction is 15-20%.
• Well tolerated, no drug-to-drug interactions, and no renal or hepatic dysfunction.
• Drug combination: Simvastatin + Ezetimibe = Vytorin.
• IMPROVE-IT trial showed that ezetimibe plus statin lowered cardiovascular events compared to statin plus placebo.

PCSK9 Inhibitors

• PCSK9 is a proprotein convertase involved in the degradation of LDL receptors in the liver.
• PCSK9 inhibitors:
  • Evolocumab (Repatha)
  • Alirocumab (Praluent)
• Excess cholesterol is primarily cleared by liver cells' receptors, but PCSK9 blocks this action by destroying the receptors.
• PCSK9 inhibitors block the action of PCSK9, allowing more receptors to function and lowering LDL cholesterol.
• Can further reduce LDL-C by ~60% for patients already on optimized statin therapy.
• FOURIER Trial: Statins plus PCSK9 inhibitors achieved a significantly lower median LDL than statins alone.
• GLAGOV Trial: Statins plus PCSK9 inhibitors achieved coronary plaque regression.

Bempedoic Acid (Nexletol)

• Bempedoic acid is a newly approved adenosine triphosphate-citrate lyase (ACL) inhibitor.
• Indication: Heterozygous familial hyperlipidemia or established ASCVD risk with a goal of achieving LDL-C targets despite maximized tolerated statin therapy.
• MOA: ACL enzyme upstream of HMG CoA reductase in cholesterol synthesis.
• Inhibition of ACL reduces cholesterol biosynthesis in the liver and decreases LDL.
• Anticipated LDL-C reduction is 18%.
• Drug combination: Bempedoic acid + Ezetimibe (Nexlizet) = LDL reduction of 38% when used maximally with statin.
• Monitor uric acid levels and be aware of the risk of gout flare and tendon rupture.

Homozygous Familial Hypercholesterolemia

• Rare condition characterized by dysfunctional LDL receptors on the liver.
• Leads to severely elevated LDL levels, >600mg/dl.
• Treatment includes specialized training and consultation, with medication options including:
  • Juxtapid
  • Kynamro
• Management often includes PCSK9 inhibitors, maximum statin therapy, and ezetimibe.
• Adding bile acid resins can be challenging due to absorption issues.
• Limited data on statin and niacin benefits.

Fibrates

• Fibrates (gemfibrozil, fenofibrate): Mainly lower triglycerides, mildly increase HDL.
• MOA: Unclear stimulation of lipoprotein lipase, enhancing the breakdown of very-low-density lipoprotein (VLDL) to LDL cholesterol.
• Studies show that fibrates added to statins may trend toward fewer cardiovascular events in patients with triglycerides >500 mg/dl and low HDL despite dietary modifications.
• Efficacy is limited, contraindicated in patients with cholecystitis, cholelithiasis, hepatic or renal disease.
• Higher risk of myopathy reported when used with statins.
• No studies in pregnant women.

Other Non-Statin Medications for Lipid Management

• 1. Niacin: Lowers triglycerides and lipoprotein (a). Poorly tolerated.
• 2. Bile Acid Resins: Indicated for triglycerides >300mg/dl fasting, heavy routine adherence burden.
• 3. Fish Oil: Need at least 4gm/day to lower triglycerides. Over-the-counter preparations have only 400-500 mg per capsule versus 1,000mg per capsule Rx strength. No proven benefit on cardiovascular outcomes.

Interactive ASCVD Risk Calculator

• Download MDCalc.
• Save the ASCVD Risk Algorithm to favorites.
• Use the calculator for different scenarios, including:
  • History of ASCVD (yes or no)
  • LDL cholesterol level
  • Age
  • Diabetes status
  • Gender
  • Total cholesterol
  • HDL cholesterol
  • Blood pressure
  • Smoking status

Lipid Management Points

• Lifestyle changes are essential for cardiovascular prevention and should never be neglected.
• "Primordial prevention" is key!
• Plaque burden risk is influenced by both the magnitude of LDL elevation and the duration of exposure.
• The new ASCVD risk categories include:
  • Low risk (<5%)
  • Borderline risk (5-10%)
  • Intermediate risk (>10%)
  • High risk (≥20%)