Health Secretary Steve Barclay said there was ‘still a question’ about whether ambulance services would cover all emergency calls during the strikes.
Unions have said they will respond to the life-threatening incidents – known as Category 1 appeals – when they go on strike on December 21 in a row over wages.
The GMB, Unison and Unite are coordinating industrial action across England and Wales after accusing the government of ignoring calls for a decent pay rise.
Mr Barclay said officials planned to meet on Thursday to discuss coverage for Category Two appeals – which cover heart attacks, strokes, epilepsy and burns.
But he said the “union indication” is that conditions such as heart attacks will be covered.
He told Times Radio: ‘We have further discussions with officials tomorrow about what are called waivers – what elements of the service they will provide.
“They said they would continue to offer life-threatening services, so those are the cats.
“There is a question of whether they will cover all cats – these are emergency responses to things like heart attacks and strokes – so it is extremely important that these are also covered.”
He said category three and four appeals are “still very important”, adding: “Obviously if those aren’t covered because of the strikes, that puts enormous pressure.
“Of course we can look at any contingency plans that we can put in place, but they will never cover the same amount as having 3,000 ambulances a day, which is about what we have on a day. typical.
“There is a risk if we cannot get the ambulances to people.”
He told Sky News the falls tend to be a category three emergency and ‘at the moment the unions are saying these things would not be covered’ but ‘the indication from the unions’ is that conditions such that heart attacks will be covered.
Mr Barclay said he was ‘open to discussions with the unions’ and later added ‘it’s not just about pay, there are many issues that affect staff, the quality of the NHS, technology, personnel and staffing levels”.
He said if everyone in the public sector received a pay rise in line with inflation it would cost £28billion.
Meanwhile, Mr Barclay told GB News that ‘the Prime Minister has held firm’ in the dispute.
The strike will come a day after members of the Royal College of Nursing staged their second walkout, also over pay.
The GMB said more than 10,000 paramedics from nine trusts in England and Wales would go on strike.
Union members will strike at South West Ambulance Service, South East Coast Ambulance Service, North West Ambulance Service, South Central Ambulance Service, East Midlands Ambulance Service, East Midlands Ambulance Service, West Midlands Ambulance Service, Welsh Ambulance Service and Yorkshire Ambulance Service. Service.
GMB representatives are prepared to meet with individual trusts to discuss life and membership cover requirements.
Paramedics, emergency orderlies, call handlers and other staff will also be released on December 28.
Unite General Secretary Sharon Graham said: “The root cause of the NHS crisis is a massive shortage of staff, as workers are leaving the NHS in droves due to low pay and impossible workloads.
“Steve Barclay just doesn’t seem to get it. The first step strategy to deal with the crisis is to create a decent compensation structure by making a decent compensation offer. Otherwise the exodus of personnel continues and the crisis worsens.
“On average, the real salary of each health worker is worth around 20% less than in 2010. The salary of a porter has fallen by 21% in real terms and that of a nurse by 26%.
“It seems, as one commentator recently put it, that NHS staff are too important to strike but not important enough to earn a living wage.
“The Health Secretary has said his door is open, but unless he tackles pay rises which can start to halt the exodus of staff – and incidentally reduce the billion pounds spent each year for agency staff – the NHS will continue to crumble.
“He needs to stop saying what he can’t do and start offering real compensation solutions.”
Sara Gorton, head of health at Unison, said: ‘The Health Secretary should do everything he can to stop strikes from happening in the NHS.
“That means talking to the unions now about the health of pay, something he has so far refused to do.
“Paramedics will establish coverage plans for each service.
“The unions will discuss this and ensure appropriate responses to emergencies on strike days.
“But instead of speculating on the consequences of a strike, Steve Barclay should focus all his energies on preventing the action from happening.”