Around 2,500 lives a year are being lost due to a "postcode lottery" in how ambulances respond to heart attack patients, a former service boss has warned.
Roger Thayne, former chief executive of the Staffordshire ambulance service, told the BBC that figures on response times and ability to resuscitate patients were "frightening".
Data obtained by the BBC shows significant variations in the performance of England's 12 ambulance services.
When adjusted for population, they show that the top ambulance service could be attempting to resuscitate three-and-a-half times as many heart attack patients as the ambulance service at the bottom of the table.
Mr Thayne said the figures exposed a health scandal and called for an inquiry into the issue.
He said: "It's absolutely frightening and totally unnecessary. We have an NHS which should be as good in any part of the country and we should not have a postcode lottery in terms of this very acute condition, the cardiac arrest.
"I estimate that we should be saving twice as many lives a year, or around 2,500 people."
Mr Thayne said more people would survive if more crews arrived in time or were equipped to carry out resuscitations.
Factors affecting failure could include slow response times, different medical procedures at the scene, and the availability of defibrillators.
Mr Thayne also accused the Government of publishing "misleading" figures on ambulance performance, particularly with regard to the survival of cardiac arrest patients.
Currently, statistics show survival rates but not the number of attempted resuscitations.
Mr Thayne said: "When these figures first came out in the middle of 2011/12, when I saw those figures, I immediately wrote to the NHS Statistical Office and said, 'This is not the way this should be presented; it is misleading.' And they ignored my remarks."
The figures suggest South Western Ambulance Service is attempting to resuscitate almost three-and-a-half times as many cardiac arrest patients as the South Central Ambulance Service NHS Foundation Trust.
However, the Government statistics show the South Central cardiac arrest survival rate as 41%, compared with 25% for South Western.
"It strongly suggests to me that the South Central crews are not getting to people in enough time to attempt resuscitation," said Mr Thayne.
"Yet their survival rates appear much better than those of their counterparts in the South West who are attempting many more resuscitations."
Mr Thayne told the BBC poorer performers were obtaining high survival rates in part because they were attempting to resuscitate fewer people.
The figures show the South Western crews are attempting resuscitation on 848 people per million head of population, compared with 243 in South Central.
Professor Jonathan Benger, national clinical director of NHS England, told the BBC: "There has been variation between ambulance trusts since collection of ambulance clinical quality indicators started in April 2011.
"The reasons for variation are multifactorial and carefully analysed by ambulance trusts, as well as in published research. Variation may arise from differences in the interpretation of the definitions and methods used for assessment, the quality of data collection, verification and returns.
"Local demographics and individual patient factors will also lead to variation in outcomes, as will the treatments provided in hospital. It would be entirely wrong to suggest that all variation can be attributed to one single factor."
A spokesman for the South Central Ambulance Service said: "This data suggests that we may have fewer cardiac arrests in the South Central area, and regional variation in cardiac arrests has been recognised previously. When we do resuscitate, a significant number of our patients survive."