Isolated Systolic Hypertension

Isolated systolic hypertension (ISH) is a systolic pressure of 140 mm Hg or more with a diastolic pressure under 90 mm Hg. Pulse pressure is usually wide, over 60 mm Hg.

It is the commonest form of hypertension after 50 years of age, and accounts for about two thirds or more of hypertension in older adults. It predicts stroke, coronary events, heart failure, atrial fibrillation, kidney disease and dementia.

In adults under 40 years, spurious ISH is common in tall, athletic young men. Brachial systolic pressure is amplified while central aortic pressure is normal, and the outlook is usually benign.

Secondary ISH is caused by high output states (thyrotoxicosis, anaemia, aortic regurgitation, arteriovenous fistula, Paget disease, wet beriberi).

Pathophysiology. Stiffening of the large arteries (elastin fragmentation, collagen deposition, calcification, glycation) raises pulse wave velocity. Reflected waves then return to the aorta in late systole and raise systolic pressure, and lower diastolic pressure and coronary perfusion.

Impaired baroreflexes and salt sensitivity in older adults add to labile pressure and orthostatic hypotension.

• Usually asymptomatic. Dizziness, falls or syncope suggest orthostatic hypotension.
• Wide pulse pressure, prominent carotid pulsation, systolic ejection murmur and a fourth heart sound.
• Target organ damage: left ventricular hypertrophy, retinopathy, reduced eGFR, albuminuria, cerebrovascular and peripheral artery disease.
• Features of secondary causes: goitre, pallor, early diastolic murmur of aortic regurgitation, fistula, bone pain.

Red flags.

• Blood pressure of 180/110 mm Hg or more with organ damage
• Fall of 20 mm Hg systolic or 10 mm Hg diastolic on standing
• Syncope, falls, or diastolic pressure under 60 mm Hg on treatment with symptoms
• Severe aortic regurgitation
• Differences between the arms of over 15 mm Hg, absent pulses or chest or back pain (aortic or subclavian disease, dissection)
• New ISH in a young patient

• Measurement. Both arms, seated and standing at 1 and 3 minutes, a validated device with the right cuff size, and ambulatory or home monitoring to confirm.
• Young adults. Ambulatory monitoring (24-hour mean under 130/80 mm Hg in spurious ISH), and central aortic pressure or pulse wave velocity where available.
• Tests. Creatinine, eGFR, urine albumin to creatinine ratio, glucose, lipids, ECG, echocardiography (left ventricular mass, aortic valve, aortic root).
• Secondary causes. TSH, haemoglobin, ferritin, alkaline phosphatase, and imaging for fistula or aortic disease when clinical features suggest them.
• Arterial stiffness by carotid femoral pulse wave velocity (over 10 m/s is raised), where available.

Differential diagnosis.

• Spurious ISH of youth
• White coat hypertension
• Pseudohypertension from calcified arteries
• High output states and aortic regurgitation
• Systolic and diastolic hypertension with a falling diastolic pressure in older age
• Anxiety, pain and drug effects
• Aortic coarctation and aortic disease
• Pheochromocytoma and other secondary hypertension

• Thresholds and targets. Treat a systolic pressure of 140 mm Hg or more in adults 65 years and over, and treat earlier with high cardiovascular risk. Aim for 130 to 139 mm Hg systolic when tolerated, individualised in frail adults and those 80 years and over. Avoid a systolic pressure under 120 mm Hg and symptomatic orthostatic hypotension.
• Lifestyle. Sodium under 2 g daily (salt under 5 g), a potassium rich diet unless kidney impairment, weight loss, exercise 150 minutes weekly, and limited alcohol.
• First line drugs. Start one drug at a low dose in frail adults and 80 years and over, and use a single pill combination in others.
  • Amlodipine 5 mg orally once daily, increased to 10 mg (maximum 10 mg daily; start 2.5 mg in older adults, frail patients and liver impairment). Ankle oedema is dose related.
  • Indapamide modified release 1.5 mg orally once daily (maximum 1.5 mg daily; avoid at eGFR under 30 mL/min/1.73 m2), or chlortalidone 12.5 mg orally once daily, increased to 25 mg (maximum 50 mg daily). Check sodium, potassium and creatinine at 2 weeks and 3 months. Stop the diuretic for sodium under 130 mmol/L.
  • Ramipril 2.5 mg orally once daily, increased every 2 to 4 weeks to 10 mg once daily (maximum 10 mg daily, and 5 mg daily at creatinine clearance under 30 mL/min). Check potassium and creatinine 1 to 2 weeks after each change. Contraindicated in pregnancy and bilateral renal artery stenosis.
  • Beta blockers and alpha blockers are not first line unless another indication exists.
• Resistant disease. Add spironolactone 25 mg orally once daily, increased to 50 mg (maximum 50 mg daily in this setting), with potassium and creatinine at 1 week and 4 weeks. Withhold at potassium over 5.5 mmol/L and avoid at eGFR under 30 mL/min/1.73 m2.
• Spurious ISH of youth. No drug treatment. Lifestyle advice, ambulatory monitoring and review every 1 to 2 years.
• Secondary causes. Treat the cause: thyroid disease, anaemia, valve surgery for severe aortic regurgitation, and bisphosphonate for Paget disease (zoledronic acid 5 mg intravenously as a single infusion, avoided at creatinine clearance under 35 mL/min).
• Orthostatic hypotension. Review drugs, avoid alpha blockers and high dose diuretics, and adjust the target.
• Statin and aspirin by cardiovascular risk (aspirin only for established vascular disease).

Special groups. Adults 80 years and over benefit from treatment when tolerated, with careful titration, falls review and sodium monitoring. Pregnancy is not affected, and ACE inhibitors and diuretics are avoided.

Monitoring. Seated and standing blood pressure at each visit. Titrate every 2 to 4 weeks until at target, then review every 3 to 6 months. Sodium, potassium and creatinine at 2 weeks and 3 months after starting a diuretic, 1 to 2 weeks after each change of ramipril, and at 1 week and 4 weeks after starting spironolactone. Falls and orthostatic symptoms at each visit.

Referral and escalation. Refer to cardiology or a hypertension service for suspected secondary causes, spurious ISH with doubt over risk, or resistant disease. Urgent for syncope, hypertensive emergency or suspected aortic disease.