Initial assessment
Ambulatory blood pressure monitoring allows assessment of the blood pressure profile over twenty-four hours and is fundamental for confirming the diagnosis of arterial hypertension, characterising specific blood pressure patterns and stratifying cardiovascular risk. It is indicated in situations of suspected white-coat hypertension, masked hypertension, grade 1 office hypertension, elevated office blood pressure in low-risk individuals without target-organ damage, as well as in the assessment of therapeutic control, blood pressure variability and the presence of nocturnal hypertension.
Diagnostic thresholds in ABPM
Interpretation should begin with analysis of mean blood pressure values using thresholds specific to ambulatory monitoring. Arterial hypertension is considered present when the twenty-four-hour mean is equal to or above one hundred and thirty over eighty millimetres of mercury, when the daytime mean is equal to or above one hundred and thirty-five over eighty-five millimetres of mercury, or when the night-time mean is equal to or above one hundred and twenty over seventy millimetres of mercury. Exceeding these values confirms the diagnosis of arterial hypertension, even if office measurements are normal.
Classification of the twenty-four-hour blood pressure profile
When the twenty-four-hour mean is elevated, the predominant blood pressure profile should be characterised. Isolated elevation of systolic blood pressure with normal diastolic pressure defines isolated systolic hypertension, a common phenotype in older adults associated with arterial stiffness and heterogeneous prognostic significance. Isolated elevation of diastolic blood pressure defines isolated diastolic hypertension, more common in younger individuals. Concomitant elevation of systolic and diastolic blood pressure corresponds to systolic-diastolic hypertension, generally associated with higher global cardiovascular risk.
Assessment of night-time blood pressure
A normal global twenty-four-hour mean does not exclude arterial hypertension. Specific analysis of the night-time period is essential, since elevated night-time values identify nocturnal hypertension or masked hypertension. These phenotypes are associated with a higher risk of cardiovascular events, progression of target-organ damage and worse prognosis, being particularly relevant in patients with diabetes, chronic kidney disease, obstructive sleep apnoea or high cardiovascular risk.
Circadian blood pressure pattern (dipping)
ABPM interpretation should include analysis of the circadian blood pressure pattern. The dipper pattern, defined by a night-time reduction equal to or above ten percent and below twenty percent compared with the daytime period, is considered physiological and is associated with relatively lower cardiovascular risk. The non-dipper pattern, characterised by a reduction below ten percent, is associated with increased cardiovascular risk and target-organ damage. The reverse-dipper pattern, in which night-time blood pressure is higher than daytime blood pressure, corresponds to the phenotype with the worst prognosis.
Extreme dipper — clinical significance
The extreme dipper pattern, defined by a night-time reduction greater than twenty percent, has prognostic significance that depends on the clinical context. In some patients, particularly older adults or those receiving intensive antihypertensive therapy, it may be associated with an increased risk of cerebral or myocardial ischaemia, syncope and falls, and should therefore be interpreted cautiously and integrated with symptoms and current treatment.
Clinical implications and therapeutic approach
Identification of higher cardiovascular risk phenotypes, such as nocturnal hypertension and non-dipper or reverse-dipper patterns, should prompt careful clinical reassessment. In these contexts, therapeutic intensification may be considered, including adjustments to drug class, dose or timing of administration, as well as investigation of secondary causes of hypertension, such as sleep apnoea, kidney disease, autonomic dysfunction or pharmacological interference.
Hypotension and blood pressure variability
ABPM also allows identification of hypotensive episodes, including autonomic, postural, postprandial or drug-induced hypotension, which are particularly relevant in older, frail or polymedicated patients, and in individuals with compatible symptoms such as dizziness, syncope or falls. This information is essential for adjusting therapy and preventing adverse events.
Special situations
In pregnancy, ambulatory blood pressure monitoring is useful for clarifying elevated office blood pressure values and supporting the diagnosis of gestational hypertension or pre-eclampsia. It can also be used to monitor therapeutic response and reduce the risk of unnecessary interventions.
Follow-up and reassessment
Appropriate ABPM interpretation requires integrated analysis of mean blood pressure values, systolic and diastolic profiles, night-time behaviour and the circadian blood pressure pattern. This approach allows more accurate risk stratification, guides individualised therapeutic decisions and contributes to safer and more effective management of arterial hypertension, beyond isolated office blood pressure measurement.
