NEW figures suggest the ambulance service for Bucks has the worst survival rate for patients whose hearts suddenly stop beating.

Out of a sample of 160 incidents during 2011-12, the out-of-hospital cardiac arrest survival rate for the South Central Ambulance Service was 10.8 per cent.

The best performer out of 12 trusts was the London Ambulance Service - where the 31.7 per cent survival rate included the remarkable case of Bolton footballer Fabrice Muamba.

It is the first time all ambulance services in England have measured the cardiac arrest survival rate - with the figures submitted to the Department of Health for collation.

South Central Ambulance Service, which also covers Berkshire and Oxfordshire, urged caution when considering the stats - saying there are "real challenges" in obtaining reliable data in this area.

Spokesman James Keating-Wilkes added: "This means it’s hard to make direct performance comparisons until each ambulance service is able to get robust data back from all hospitals.

"The trust is working closely with other NHS organisations to improve the quality of data available on patient outcomes and has put a number of initiatives in place towards increasing the accuracy of data reporting.

"SCAS is very focussed on ensuring that we work together with our partners in all our emergency departments to continue to improve cardiac arrest survival rates.

"Figures are reported on a monthly basis to the Department of Health and as such fluctuations in these are inevitable."

There were about 1,500 cardiac arrests in the South Central region last year - but the stats have been drawn from 160 cases using the internationally-recognised Utstein cardiac arrest survival rate.

The figure achieved by London Ambulance Service is among best to be published in Europe and represents a marked increase in the last decade.

Bosses attributed the improvements to staff reaching patients quicker and delivering more effective clinical care.

It also appears that more members of the public than ever before are attempting cardiopulmonary resuscitation (CPR) while ambulance staff are on the way, which can double the survival chances.