Is your blood pressure rising undetected?

This study evaluated whether blood pressure levels change throughout the day. 

When blood pressure is measured, the value is given as two numbers; for example 120/80 mmHg. The first (or top number) is the pressure inside arteries when the heart is contracting (systolic blood pressure). The bottom number is the pressure inside arteries when the heart is relaxed (diastolic blood pressure).

Hypertension (high blood pressure) is defined as blood pressure greater >140/90 mmHg. When blood pressure is too high it can damage the arteries, leading to heart attacks, strokes, arrhythmias (heart rhythm disturbances), kidney damage and more.

When a patient is receiving treatment for hypertension, their blood pressure needs to be measured during regular check-ups in order to make sure their blood pressure is under control. However, it has become clear that a person’s blood pressure can change greatly throughout the day. This can lead to someone being classified as having well controlled blood pressure at their clinic visits (clinic blood pressure), but their blood pressure may rise during the night (masked uncontrolled hypertension or MUCH). This means that these patients may be at a higher risk of developing health problems associated with hypertension, as their high blood pressure is undetected.

A new way of measuring blood pressure at home is called ambulatory blood pressure monitoring’ (ABPM). ABPM involves measuring blood pressure at regular intervals (every 20-30 minutes) over a 24-hour period, even in sleep.

This study investigated if patients who were being treated for hypertension and who had apparently controlled blood pressure were experiencing masked hypertension (normal clinic blood pressure but high out-of-office blood pressure). This study analysed blood pressure levels of 14,840 patients who were receiving treatment for hypertension and who had controlled clinic blood pressure values of < 140/90 mmHg. After the clinic reading, ABPM was measured every 20 minutes for a 24-hour period.

Masked uncontrolled hypertension was diagnosed if normal seated clinic blood pressure was <140/90 and 24-hour ambulatory systolic blood pressure was ≥130 and/or diastolic blood pressure was ≥80 mmHg. This study found that 31.1% of patients had masked uncontrolled hypertension. The prevalence of MUCH was significantly higher in males, patients with borderline high clinic blood pressure (130 –139/80 – 89 mmHg), and patients at high cardiovascular risk (smokers, diabetic and obese patients). Masked uncontrolled hypertension was most often because of poor control of blood pressure at night.

The aythors suggested that clinic blood pressure monitoring alone is thus inadequate to control blood pressure and that ABPM should be more widely used to optimize blood pressure control.

Despite the advantages, patients may experience discomfort or sleep disturbance when wearing the inflatable ABPM cuff. 

If you are currently receiving medication for hypertension, or you are worried about your blood pressure, discuss with your doctor the possibility of monitoring your blood pressure at home to see if you have masked uncontrolled hypertension.