HTN: Nuts & Bolts

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What & Why

Hypertension (HTN) is a sustained BP >130/80 mmHg. 

  • The 2017 ACC/AHA guidelines go further in terms of categorization:
    • normal: SBP <120 and DBP <80 mmHg
    • elevated: SBP 120-129 and DBP <80
    • stage 1 HTN: SBP 130-139 or DBP 80-89
    • stage 2 HTN: SBP ≥140 or DBP ≥90

Changes to the definition: 

  • Previous definition of HTN from the JNC7 Guidelines was a BP of >140/90
  • Current guidelines lowered the threshold because of evidence from the SPRINT trial that at BP lower than 140/90 there is still increased cardiovascular risk

Quick facts: 

  • 45% of American adults have HTN (57% of non-Hispanic blacks)
  • HTN is a major contributor to CAD, stroke, HF, and kidney disease, and increases risk of morbidity/mortality from COVID-19
  • Even “pre-hypertensive” patients have a higher risk of morbidity/mortality, and people who achieve BP control in the lower range have better cardiovascular outcomes
  • Despite multiple pharmacological antihypertensive agents on the market, BP control in US adults has worsened over time

Contributors to HTN: 

  • Overweight/obesity
    • Correlation between BMI and BP
    • Physical activity = inversely related to BP
  • Genetics
    • All identified genetic variants account for only 3.5% of BP variability
  • Sodium intake 
    • Americans on average eat 3400mg of sodium per day
    • Recommended = 2300mg
    • Potassium intake can help counteract

Screening

USPSTF recommendation (Grade A): The USPSTF recommends screening for hypertension in adults 18 years or older with office blood pressure measurement. The USPSTF recommends obtaining blood pressure measurements outside of the clinical setting for diagnostic confirmation before starting treatment.

  • Did you catch that 2nd sentence? It’s important to check BP measurements outside the clinical setting to assess the possibility of white coat HTN and masked HTN.

How to check BP in clinic:

  1. No caffeine or exercise 30 minutes before measurement
  2. Sitting alone (without talking) for at least 5 minutes prior to measurement
  3. Feet flat on the floor and legs uncrossed
  4. Arm rest at heart height (i.e., patient should not be holding their arm up)
  5. Back supported
  6. Empty bladder (see below!)
  7. Correct cuff size
  8. Automated readings may be superior to manual!
  9. New patient? Check BP in both arms!
  • Fun fact: Having a full bladder can increase BP by 10-15 mmHg in most patients!
  • The most precise way to choose the correct BP cuff size is to measure the circumference of the arm and match it with the correct size on a sizing chart. The circumference should be measured midway between the acromion and the olecranon. The bladder of the cuff should be approximately 80% of the arm circumference and the width of the cuff should be about 40% of the arm circumference.
  • Looking at the picture on the left, the patient’s arm should be smaller in diameter than the line at the bottom of the cuff (arm should fit inside the line.)
  • Looking at the picture on the right, you can see the two range lines. When you encircle the arm with the cuff, the end of the cuff (index line) should fall between the two white lines by the velcro.

24-hour BP monitoring:

  • Gold standard for home BP monitoring
  • Patient wears device for 24 hours—BP cuff inflates every 15-20 minutes (30-60 minutes overnight)
    • Nocturnal measurements tend to have a stronger association with CV risk
  • BP readings are averaged over 24 hours

Ambulatory BP monitoring:

  • Recommended for anyone on BP meds, those engaging in lifestyle interventions, or those who need monitoring for any reason
  • Same instructions as for clinic measurements
  • Inform patients to take 2 or 3 readings and average them
  • Validate BP is an interesting resource on cuff accuracy and cost

Management: Lifestyle

Lifestyle modifications are recommended for any degree of HTN: 

  • DASH diet can reduce SBP by 11 mmHg
    • Vegetarian and Mediterranean diets have also shown some benefit to reduction in BP, but not as much as DASH
  • Lower sodium intake (ideally <1500 mg/day, which can reduce SBP by 5-6 mmHg, although more reasonable goal is <2300)
  • Weight loss and physical activity (BP decreases ~1 mmHg for each 1 kg of weight loss; 150 minutes of moderate aerobic activity per week can reduce SBP by 5-8 mmHg)
  • Minimize alcohol use (Men <2 standard drinks daily; Women <1 standard drink daily)
  • Decrease caffeine consumption to 1-2 cups of coffee per day
  • Obtain 6-8 hours of uninterrupted sleep per night 
    • Poor sleep = more sympathetic stimulation, increased activity of the RAAS → increased BP

Management: Pharmacotherapy

Per the 2017 ACC/AHA Guidelines, we should consider initiating pharmacotherapy when 

  • Average BP >130/80 mmHg or higher AND
    • Previous cardiac event
    • 10-year ASCVD risk >10%
  • Average BP >140/90
    • Regardless of ASCVD risk

And remember – the above BP measurements are sustained measurements (on 2 or more occasions) that are ideally also confirmed in an out-of-office setting. 

First-line therapies: 

  • Angiotensin-converting enzyme inhibitors (ACEi) or angiotensin-receptor blockers (ARBs)
  • Thiazide diuretics
  • Calcium channel blockers

Choice of medical therapy: 

  • No right answer as to which first-line agent to choose
  • Each class of drug is roughly equivalent in amount of BP reduction
  • Some patients will respond to one drug, not another
  • All major societies (AHA/ACC, ISH, ESH) have concluded that it is the AMOUNT of blood pressure reduction, NOT the antihypertensive drug, that is the major determinant in reduction of CV risk
  • When choosing a drug, consider patient-specific characteristics and medical comorbidities

ACEi/ARBs

Already indicated for a variety of other comorbidities:

  • HFrEF
  • History of acute MI 
  • Diabetic nephropathy
  • CKD with proteinuria 
  • Glomerular disease or nephrotic syndrome

Tend to be more effective in younger people (<50), but are also teratogenic (especially in 2nd and 3rd trimester). 

Easily titratable. 

Thiazide diuretics

ALLHAT trial: Chlorthalidone lowered SBP in follow up more than ACEi (lisinopril) or CCB (amlodipine). 

  • Lower rate of heart failure compared with amlodipine and lisinopril 
  • Primary outcome (fatal coronary heart disease or non-fatal MI) – same in all 3 drugs

Stimulate tubular reabsorption of calcium, decrease urinary calcium excretion. 

  • Good bone density (decreased hip/pelvic fractures in ALLHAT)
  • Good for kidney stones associated with hypercalciuria

Also increase reabsorption of uric acid and reduce urinary excretion (i.e., bad for gout). 

Associated with hypokalemia, hyponatremia, and increased urinary frequency. 

Cannot use in renal failure (chlorthalidone only if GFR >30, HCTZ only if GFR >45)

CCB (dihydropyridine)

No absolute indication. 

No lab monitoring necessary. 

Generally benign, but can lead to peripheral edema (unrelated to fluid retention, due to vasodilation). 

Avoid in HFrEF (though amlodipine is safe and well-tolerated). 

More than 1?

  • ACC/AHA guidelines recommend initiating 2 first line agents of different classes as separate agents or in a fixed-dose combination pill if BP is Stage II (>140/90) and 20/10 mmHg above target) OR initiating 1 single antihypertensive agent if the person has stage 1 hypertension with BP goal <130/80 with appropriate dose titration and sequential addition of meds as needed

First combination recommended: ACEi/ARB + DHP CCB

  • Based on results of ACCOMPLISH trial
    • ACEi + amlodipine significantly better in the primary outcome (composite of death from CV causes, non-fatal MI, non-fatal stroke, angina w/ hospitalization, cardiac arrest or coronary revascularization)
    • ACEi/ARB can also help with CCB-related edema

ACEi/ARB + diuretic can be considered post-stroke, in HF, or with CCB intolerance. 

4th-line agent: Spironolactone (MRA)

  • PATHWAY2 trial compared spironolactone, bisoprolol, and doxazosin as 4th line therapies for resistant hypertension
    • Spironolactone had lower home SBPs compared to other agents
  • Cautions:
    • Can cause hyperkalemia (especially in CKD patients, concurrent ACEi/ARBs)
    • Gynecomastia (can switch to eplerenone) 

Medication Adherence

Single pill combination therapy:

  • Evidence suggests more effective blood pressure lowering from two moderately dosed meds, than one maxed out med
  • Compliance is better with 1 pill rather than 2

Home BP monitoring: 

  • Patients more amenable to taking medications if they see pressures are high

Time agents to minimize side effects and effectiveness

  • Known nocturnal hypertension – take meds at night! 
  • Diuretics – tend to be less disruptive in the morning
  • CCB edema – dosing in the evening can keep most of the side effect occurring overnight

BP Targets with Medical Therapy

Confirmed hypertension AND known CVD or 10-year ASCVD risk >10%, target <130/80 mmHg

  • SPRINT: Targeted SBP <120, but this group had pressures taken consistently in research settings (~7mmHg lower than true office settings); excluded patients with standing SBP <110 (no orthostatic hypotension)

Confirmed hypertension without additional markers of increased CVD risk, <130/80 “may be reasonable”

  • Not as strong of a recommendation

ISH guidelines – for patients >65, can target <140/90

  • Consider level of frailty, independence and tolerability of treatment

Aim for control in about 3 months

  • Should follow up in 1 month intervals after starting or dose-adjusting meds

Blog post based on Med-Peds Forum talk by Lindsey Mahoney, PGY4

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