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Question: Which home blood pressure monitors are suitable for people with atrial fibrillation?

Expert: Professor Terry McCormack, immediate past president of the British and Irish Hypertension Society, and chair of the board of directors at the Primary Care Cardiovascular Society 

None of the British and Irish Hypertension Society-validated home blood pressure monitors (HBPM) are accurate when measuring blood pressure in people with atrial fibrillation.

Automatic home blood pressure monitors use an oscillometric method to measure blood pressure. That oscillometric method requires each beat of the heart to be of a similar volume and the software forms a spheroidal shape, from which it imputes systolic and diastolic cut-offs.

The chaotic beats in atrial fibrillation distort that spheroidal shape and the cut-offs are in the wrong place. A source of confusion is that many automatic home blood pressure monitors are described as AFib suitable machines. That simply means that they can detect atrial fibrillation; it does not mean that they can accurately measure blood pressure in someone with atrial fibrillation.

The accurate way to measure blood pressure in people with atrial fibrillation is to use a stethoscope to listen for the first and fifth Korotkoff sounds with a sphygmomanometer that acts like a mercury device.

Many specialist hypertension clinics use the Accoson Greenlight 300 for this purpose.

There are monitors that can detect and listen for Korotkoff sounds, but these are not widely available and only used in a clinical setting.

It is felt that repeated measurements will give an average blood pressure that may be more accurate. Because ambulatory blood pressure monitors (ABPM) will carry out several measurements, they are felt to be more reliable.

The number of valid readings must be a minimum of 14 and that is the same for both people with atrial fibrillation and those in sinus rhythm. Therefore, for both diagnostic and follow-up measurements in an out-of-office setting, it is probably best to use ABPM.

ABPM is not generally popular with patients and there are people in whom it is contraindicated, such as those with severe mental health issues and women with bilateral mastectomies at risk of lymphoedema.

In those cases, you could use home blood pressure monitoring, but you do need at least 14 readings. Cuffless technologies may offer a solution when they are fully validated, as they do not use an oscillometric pattern to read the blood pressure. However, many of them do require a monthly brachial HBPM to check their accuracy.