Angioplasty unblocks the arteries
Availability of the gold standard heart attack treatment varies across England and Wales, a report says.
The Myocardial Ischaemia National Audit Project (MINAP) recorded a significant rise in the number of patients receiving a primary angioplasty.
However, the procedure - which unblocks arteries using a balloon and a stent to keep blood flowing - is still only given to around one in five patients.
Ministers have said they want all patients to receive it.
The MINAP report found that 4,472 patients were treated with primary angioplasty in England in 2007-08 - a 42% rise from the previous year.
Wales recorded a 20% rise - up from 44 to 53 patients.
However, seven out of 30 English cardiac networks had "very restricted access" to primary angioplasty services, treating fewer than 10 cases in 2007/8.
North East London treated all its patients with primary angioplasty. In contrast in Cheshire and Merseyside just 6% of patients received the treatment.
A total of 54 hospitals in England, and two in Wales carry out the procedure.
Dr Clive Weston, consultant cardiologist and associate director of MINAP, said there were not currently enough specialist doctors and centres to offer primary angioplasty across the whole of the UK.
He said some hospitals provide it only during office hours because they don't have enough specialists to be on call for a continuous rota.
However, he said patients who sought help quickly and received clot-busting drugs were still getting good treatment.
Dr Mike Knapton, of the British Heart Foundation, said significant improvements had taken place since the previous audit 12 months ago.
However, he said: "There are significant variations in the access to treatment across England and Wales and this inequality must be addressed."
Professor Roger Boyle, the government's national clinical director for heart disease and stroke, set out the clinical case for moving to a primary angioplasty service in December 2006.
He said: "We continue to see improvements in treatment at all levels of the health service, from more pre-hospital treatment given by paramedics, to increased numbers of hospitals able to provide lifesaving primary angioplasty.
"In the light of such good progress, it is immensely rewarding to see the mortality rate for heart attack patients continue to fall."
In England, more than six out of 10 patients with heart attacks receive either primary angioplasty or clot-busting drugs within three hours of the onset of their symptoms.
After this time the effectiveness of both treatments falls, although primary angioplasty may still provide some benefit.