Practices will be expected to pay for the monitors, costing around £1,000 each, but savings will come from reducing PCT drug spend and cutting GP appointments for people with 'white coat' hypertension.
A GP involved in developing the guidance said practices or consortia should look at negotiating 'invest to save' local enhanced services (LESs) with PCTs to pay for the monitors to implement the guidance.
In updated guidelines, NICE now recommends a diagnosis of primary hypertension should be confirmed using 24-hour ambulatory BP monitoring.
Analysis suggests that the diagnostic criteria would be cost-saving within a year.
Within five years, a practice with 10,000 patients would save £2,000 a year and the NHS in England would be saving £10m a year.
Professor Richard McManus, of Birmingham University and a local GP, said a practice of 10,000 patients would need just one ambulatory BP monitor.
'GP income is the thing that is going to be used to buy the machine, whereas the drug savings are nothing to do with GP income,' he said. 'It is an obvious thing to do one of these "invest to save" LESs.'
Dr Michelle Drage, chief executive of Londonwide LMCs, said practices should not worry immediately about buying new machines. A variety of ways of providing ambulatory monitoring to patients are likely to develop, and practices should not necessarily aim for contractual solutions, she said.
NICE's revised recommendations contain no major changes to the treatment thresholds and targets, but the treatment algorithm has been simplified.
The guidelines recommend a calcium channel blocker as the first-line agent for patients aged over 55 years or of African or Caribbean family origin and an ACE inhibitor or angiotensin II receptor blocker for under 55s.