Hypertension: A Comprehensive Clinical Overview

Definition and Classification

2025 Update: The 2025 AHA/ACC/AANP Hypertension Guideline replaces the 2017 guideline and is now a "living document" updated with evidence from 2015 onward. Note: an erratum was issued (PMID 42160500).

Epidemiology

• Hypertension affects approximately 1 in 3 adults in the United States.
• Black adults have significantly higher prevalence than White or Hispanic adults (age-adjusted data from NHANES 2017-2018).
• Hispanic paradox: Despite similar hypertension prevalence to White adults, Hispanic Americans have ~10% lower coronary heart disease and ~30% lower heart disease mortality than Whites.
• Overweight and obesity may account for up to 75% of essential hypertension - Fuster and Hurst's The Heart, 15th Edition, p. 222.

Risk Factors

Nonmodifiable

• Older age (strongest predictor)
• Male sex
• Race/ethnicity
• Rare genetic variants
• Low socioeconomic status / psychosocial stress

Modifiable

• Obesity/adiposity - abdominal obesity (waist ≥102 cm men, ≥88 cm women) independently raises hypertension risk (OR 1.51)
• Sedentariness / physical inactivity
• High sodium / low potassium diet
• Excessive alcohol intake
• Smoking
• Obstructive sleep apnea
• Diabetes mellitus (bidirectional relationship confirmed by Mendelian randomization)

Pathophysiology

Primary (Essential) Hypertension (~90-95%)

• Renin-Angiotensin-Aldosterone System (RAAS) overactivation - Angiotensin II (AngII) causes vasoconstriction, sodium retention, and end-organ damage via AT1 receptors
• Sympathetic nervous system hyperactivity - increased cardiac output and peripheral vascular resistance
• Renal sodium retention - impaired pressure-natriuresis
• Vascular remodeling - structural changes in arterioles increasing resistance
• Kallikrein-Kinin System (KKS) dysfunction - decreased urinary kallikrein in hypertensive patients suggests a protective role of the KKS; inversely, ACE inhibitors attenuate nephrosclerosis partly via enhanced kinin activity - Brenner and Rector's The Kidney, p. 469

Secondary Hypertension (~5-10%)

• Renal artery stenosis (renovascular hypertension)
• Primary hyperaldosteronism
• Pheochromocytoma
• Obstructive sleep apnea
• Thyroid disorders
• Medication-induced (NSAIDs, oral contraceptives, sympathomimetics)

Complications (Target-Organ Damage)

Evaluation

BP Measurement

• Office BP: ≥2 readings, ≥2 visits
• Home BP monitoring (HBPM): Preferred for detecting white-coat hypertension and masked hypertension, guiding therapy
• Ambulatory BP monitoring (ABPM): Gold standard for diagnosis

Initial Workup

• History: Symptoms, medications, lifestyle, family history, secondary causes
• Physical exam: Weight, fundoscopy, cardiac/renal exam
• Labs: BMP (creatinine, electrolytes, glucose), urinalysis with microalbumin, lipid panel, TSH
• ECG: LV hypertrophy assessment

Treatment

Lifestyle Modifications (First for Stage 1 without high CVD risk)

• Weight loss (most effective single intervention)
• DASH diet (high fruits/vegetables, low sodium, low saturated fat)
• Sodium restriction (<2.3 g/day)
• Increase potassium intake
• Regular aerobic exercise (150+ min/week)
• Limit alcohol
• Smoking cessation

Pharmacologic Treatment

Important: Beta-blockers are NOT recommended as initial therapy in uncomplicated hypertension - they are less effective than other first-line drugs for stroke prevention - Goldman-Cecil Medicine, p. 755. Never combine two RAAS inhibitors (ACEi + ARB) due to minimal additive BP benefit but high risk of renal impairment and hyperkalemia.

Combination Therapy

• ACEi/ARB + CCB (e.g., ramipril + amlodipine)
• ACEi/ARB + thiazide-like diuretic (e.g., telmisartan + chlorthalidone)
• A single pill with quarter-doses of four agents (irbesartan, amlodipine, indapamide, bisoprolol) is a validated low-dose quadruple strategy.

BP Targets

Special Populations

Elderly

• Start with low doses; titrate slowly
• High risk of orthostatic and postprandial hypotension
• Monitor for hyponatremia with thiazides
• HBPM/ABPM essential to avoid overtreatment

Diabetes

• ACEi or ARB are first-line (proven renoprotective, cardioprotective)
• SGLT2 inhibitors provide additional BP reduction and CV/renal benefit
• 85% of diabetic patients in the ACCORD trial were on antihypertensives

Chronic Kidney Disease

• ACEi or ARB preferred (KDIGO 2021)
• Target SBP <130 mmHg

Pregnancy

• ACEi and ARBs are absolutely contraindicated in pregnancy (teratogenic)
• Use methyldopa, labetalol, or nifedipine

Peripheral Arterial Disease

• Beta-blockers are safe in PAD and do not worsen intermittent claudication (confirmed by meta-analysis) - Textbook of Family Medicine 9e, p. 701
• ACE inhibitors offer vascular protection beyond BP lowering alone (HOPE/EUROPA data)

Resistant Hypertension

• Medication nonadherence
• Uncontrolled secondary hypertension (especially obstructive sleep apnea, primary aldosteronism)
• Volume overload
• Interfering substances (NSAIDs, stimulants, decongestants)

Key Takeaways

1. Hypertension is defined as SBP ≥130 or DBP ≥80 mmHg (ACC/AHA 2017/2025).
2. Most patients (~90-95%) have essential (primary) hypertension with multifactorial causation.
3. Lifestyle changes are first-line but most patients eventually need pharmacotherapy.
4. First-line drugs: ACEi, ARBs, CCBs, thiazide diuretics. Beta-blockers are not first-line in uncomplicated hypertension.
5. Never combine ACEi + ARB.
6. A new 2025 AHA/ACC Guideline is now the authoritative reference, replacing the 2017 version.