Antihypertensives

Antihypertensives / Pharmacotherapy of Hypertension

1. Definition, epidemiology & rationale for treatment

• Hypertension (HT) is the most common cardiovascular disease and the single most common reason for physician office visits; it is a risk factor, not a disease in itself, and the normotensive/hypertensive cut-off is arbitrary — operationally, "that level of BP at or above which long-term treatment reduces cardiovascular mortality" (KDT 8e Ch.41, pp.604–5).
• Prevalence rises with age: ~50% of people aged 60–69 are hypertensive, increasing further beyond 70; using the 2017 ACC/AHA ≥130/80 mmHg definition, 45% of US adults and 74% of those ≥60 yr are hypertensive (G&G 14e Ch.32, p.625; Katzung 16e Ch.11, p.177).
• Sustained arterial HT damages vessels in kidney, heart, brain and retina, causing left-ventricular hypertrophy (LVH) and vascular pathology; it is the principal cause of stroke, a major risk factor for coronary artery disease (CAD), MI and sudden cardiac death, and a major contributor to heart failure, renal insufficiency and aortic dissection (G&G 14e Ch.32, p.625).
• Cardiovascular risk is continuous and graded: lowest at SBP <120 and DBP <80 mmHg, and doubles for every 20/10 mmHg increment from 115/75 mmHg upward — this continuity is why any single definition of HT is necessarily arbitrary (G&G 14e Ch.32, p.625; Katzung 16e Ch.11, p.178).
• In adults >50 yr, systolic BP predicts adverse outcomes better than diastolic; pulse pressure (SBP − DBP) adds predictive value, reflecting large-artery stiffening with ageing/atherosclerosis (G&G 14e Ch.32, p.625).
• Isolated systolic hypertension (ISH) — raised SBP with normal DBP — indicates large-artery stiffening in the elderly; in young men it is strongly associated with smoking and is not benign (G&G 14e Ch.32, p.625; Katzung 16e Ch.11, p.178).
• Concomitant target-organ damage (retinal haemorrhages/exudates/papilloedema, ECG/echo LVH) worsens prognosis at any given BP; coexisting smoking, diabetes and ↑LDL compound morbidity and mortality multiplicatively (G&G 14e Ch.32, p.626).
• Purpose of treatment is to reduce cardiovascular risk and improve life expectancy, NOT merely to lower a number; effective therapy reduces stroke, heart failure and CAD (reduction in MI risk is comparatively smaller). Drug selection should be driven by morbidity/mortality evidence, not BP reduction alone (G&G 14e Ch.32, p.626; DiPiro 12e Ch.30).
• Quantified benefit of treatment: stroke ↓30–50%, heart failure ↓40–50%, CAD ↓~15% (KDT 8e Ch.41, p.615).
• Control remains poor: in US surveys only ~50–52% of treated hypertensives are controlled — addressing clinical inertia (no therapeutic change at a visit despite uncontrolled BP) and adherence is as important as drug choice (Katzung 16e Ch.11, p.177; DiPiro 12e Ch.30; G&G 14e Ch.32, p.625).