What are the ambulatory blood pressure monitoring thresholds that define hypertension, and how should they be applied to a patient with a clinic blood pressure of 190/115 mm Hg but no target‑organ damage?

Ambulatory Blood Pressure Monitoring Thresholds for Hypertension

Hypertension is defined by ambulatory blood pressure monitoring (ABPM) as a 24-hour average ≥130/80 mmHg, daytime average ≥135/85 mmHg, or nighttime average ≥120/70 mmHg. 1

ABPM Diagnostic Thresholds

The 2024 ESC Guidelines provide the most current and authoritative thresholds for defining hypertension using ABPM 1:

• 24-hour average: ≥130/80 mmHg
• Daytime average: ≥135/85 mmHg
• Nighttime average: ≥120/70 mmHg

These thresholds correspond to an office blood pressure of ≥140/90 mmHg 1. The ACC/AHA guidelines similarly define hypertension using ABPM with a 24-hour threshold of ≥130/80 mmHg, daytime ≥135/85 mmHg, and nighttime ≥120/70 mmHg 1.

Application to Your Patient with Office BP 190/115 mmHg

For a patient with office BP of 190/115 mmHg and no target organ damage, ABPM is not required for diagnosis—this patient has confirmed Grade 2 hypertension and requires prompt treatment initiation within one week. 1

Here's the algorithmic approach:

When ABPM is NOT Needed:

• Office BP ≥180/110 mmHg requires assessment for hypertensive emergency, then prompt confirmation (preferably within a week) before starting treatment if no emergency exists 1
• Your patient's BP of 190/115 mmHg falls into this category—the diagnosis is already established 1
• The absence of target organ damage does not change this recommendation at this BP level 1

When ABPM IS Indicated:

ABPM should be used for diagnostic confirmation in these specific scenarios 1:

• Office BP 130-159 mmHg systolic or 80-99 mmHg diastolic (to exclude white coat hypertension before starting treatment) 1
• Office BP 160-179/100-109 mmHg (confirmation within 1 month using office or out-of-office methods) 1
• Suspected white coat hypertension (office BP elevated but clinical suspicion of normal out-of-office BP) 1
• Suspected masked hypertension (office BP normal but risk factors present) 1

Technical Requirements for Valid ABPM

For accurate interpretation, ABPM must meet these criteria 1:

• Minimum 70% usable BP recordings required (typically ≥27 measurements over 24 hours) 1
• Measurements at 15-30 minute intervals during daytime (7 AM to 11 PM) 1
• Measurements at 30-60 minute intervals at night (11 PM to 7 AM) 1
• Preferably seven nocturnal readings obtained 1
• Patient diary recording activities, medications, and sleep times 1
• Review raw BP values for outliers or erroneous readings before using mean values 1

Critical Clinical Pitfall

The most important caveat: Do not delay treatment in patients with markedly elevated BP (≥180/110 mmHg) waiting for ABPM confirmation. 1 The 2024 ESC Guidelines are explicit that delays in treatment for BP 160-179/100-109 mmHg are associated with increased cardiovascular event rates 1. Your patient with BP 190/115 mmHg requires even more urgent action.

Comparison with Home BP Monitoring

While ABPM remains the gold standard, home BP monitoring (HBPM) uses a threshold of ≥135/85 mmHg to define hypertension 1. However, approximately 15% of patients show diagnostic disagreement between ABPM and HBPM, with about half representing clinically significant differences >5 mmHg 1. For your patient with such markedly elevated office BP, either method would confirm hypertension, but neither is necessary for diagnosis 1.