NICE guidance - WatchBP Home A for opportunistically detecting atrial fibrillation (AF) during diagnosis and monitoring of hypertension

NICE state (1):

• case for adopting WatchBP Home A in the NHS, for opportunistically detecting asymptomatic atrial fibrillation during the measurement of blood pressure by primary care professionals, is supported by the evidence
  • available evidence suggests that the device reliably detects atrial fibrillation and may increase the rate of detection when used in primary care. This would allow prophylactic treatment to be given to reduce the incidence of atrial fibrillation-related stroke
  • WatchBP Home A should be considered for use in people with suspected hypertension and those being screened or monitored for hypertension, in primary care
    
    
• people suspected of having atrial fibrillation after use of WatchBP Home A should have an electrocardiogram (ECG)

Notes:

• the WatchBP Home A device (Microlife) is an oscillometric blood pressure monitor
  • while recording blood pressure, it automatically detects pulse irregularity that may be caused by symptomatic or asymptomatic atrial fibrillation
  • device measures blood pressure based on the guidelines from the European Society of Hypertension (ESH), the American Heart Association (AHA) and the British Hypertension Society (BHS)
  • can be used for diagnosing hypertension in a clinical setting with the measurement taken under the supervision of a clinician. If hypertension is detected or suspected, the instructions for use state that the device could also be used by the person in their home for monitoring blood pressure over a longer period
    
    
• WatchBP Home A device
  • has an embedded algorithm that calculates the irregularity index (standard deviation divided by mean) based on interval times between heartbeats. If the irregularity index exceeds a defined threshold value, atrial fibrillation is likely to be present and an atrial fibrillation icon is displayed on the device
  • if atrial fibrillation is persistent, the diagnosis will be confirmed by an ECG in line with the NICE clinical guideline on atrial fibrillation
  • if atrial fibrillation is intermittent (paroxysmal), further ambulatory electrical monitoring tests may be needed to establish the diagnosis. To minimise the potentially misleading effect of premature beats when detecting pulse irregularity, each of the pulse beat intervals that deviates more than 25% from the average interval time is excluded from analysis
    
    
• The WatchBP Home A device
  • can be used either in 'diagnostic' mode (4 measurements, 2 between 6 am and 9 am, and 2 between 6 pm and 9 pm, taken on 7 consecutive days) or in 'usual' mode (single measurements taken at any time)
  • results are stored in an internal memory or can be downloaded to a removable memory device and taken to the clinician for evaluation
  • in diagnostic mode, this would be after 7 days of monitoring, whereas a variable interval would be agreed with the clinician for monitoring in 'usual' mode. The device automatically displays the mean morning, evening and overall blood pressure results in a table

Reference:

• NICE (January 2013). WatchBP Home A for opportunistically detecting atrial fibrillation during diagnosis and monitoring of hypertension