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Even though heart attack patients are getting faster treatment at US hospitals, death rates remain relatively unchanged, a new study finds.
Over a four-year period, researchers found that the average time from when heart attack patients entered a hospital until they underwent angioplasty – a procedure to reopen blood vessels – improved by 16 minutes. This timeframe is referred to as door-to-balloon time, because angioplasty uses a balloon-like device to push open narrowed arteries.
"The door-to-balloon time rates dropped significantly, but we were disappointed to see that there wasn't a decline in mortality," said the study's lead author, Dr Daniel Menees, an assistant professor at the University of Michigan and director of the university's interventional cardiology fellowship program.
Menees said the findings highlight the fact that hospital door-to-balloon time is only one part of heart attack treatment. "Even when we act quickly, heart cells are dying," he said. "By the time patients get to the hospital and get into treatment, it's been two to three hours and there's only so much heart we can save."
That doesn't mean that time isn't critical, he added.
"There's benefit to having a quick diagnosis and prompt treatment," he said. "People need to recognise the possibility that they could be having a heart attack and get to the hospital. I'd rather someone come in with symptoms that turn out not to be a heart attack than have someone sitting at home with a heart attack until it's too late."
Results of the study are published in the 5 September issue of the New England Journal of Medicine.
The study included nearly 100 000 people with heart attacks who underwent angioplasty to treat it. This procedure involves threading a catheter into a coronary artery to open up narrowed or blocked arteries. Once the artery is reopened, a metal mesh tube called a stent is often placed in the artery to keep it open.
Door-to-balloon times are currently considered a measure of quality, according to Menees.
Results of the study
During the first 12 months of the study – July 2005 to June 2006 – the average door-to-balloon time was 83 minutes. During the last 12 months of the study – July 2008 to June 2009 – that time dropped to 67 minutes.
By the last year of the study, 83% of patients had door-to-balloon time of 90 minutes or less, compared to just 60% during the study's first year.
However, there was no corresponding drop in in-hospital or 30-day mortality rates, according to the study.
Menees said he doesn't think it's time to abandon the idea of a faster door-to-balloon time yet. There may be benefits from a faster time that weren't quantified in this study. It's possible the shorter times might lead to long-term benefits in mortality or other measures, such as fewer people with heart failure.
He said, however, that faster door-to-balloon times likely wouldn't make any additional gains in death rates, and might increase the odds of mistakes. "There's a limitation to how fast we can go," he said. "The faster we go, the more prone to errors we might be in the race against the clock."
Difficult to go faster
Dr Kirk Garratt, director of interventional cardiovascular research at Lenox Hill Hospital in New York City, agreed. "Going much faster will be hard to do," he said. "By skipping the emergency room, we can shave another 20 minutes off the door-to-balloon time, but we don't have any evidence that it will save many additional lives. And sometimes patients really need to stop in the emergency room first, especially if they're unstable."
Garratt said it may be time to focus on something other than death rates. "Maybe we're saving everybody who can be saved if we treat them within 90 minutes, but opening a blocked artery as fast as possible will still make a heart attack as small as it can be," he said. "This means heart attack survivors might have stronger hearts with, hopefully, fewer problems."
If cutting down on the time to treatment isn't making a difference in death rates, Garratt said, "it's time to start thinking differently about heart attack management."
"[Although] door-to-balloon time gets a lot of attention, it's probably just one small part of the bigger picture," Menees said. "By focusing on door-to-balloon time, maybe we're missing out on other opportunities."
More information
Learn more about angioplasty and stenting from the US National Library of Medicine.
