New Haven, CT - Large deficiencies still exist in the performance of hospitals in providing timely treatment of ST-segment-elevation MI, with substantially longer times to treatment for percutaneous coronary intervention (PCI) in patients presenting during hospital off-hours, according to the results of a new study [1]. Investigators suggest that better systems need to be implemented to ensure that patients are treated within the American College of Cardiology and American Heart Association (ACC/AHA) guideline-recommended treatment times.

"When we're using drugs, the fibrinolytic therapy, the data suggest that there are at least no greater delays during off-hours," said lead investigator Dr Harlan Krumholz (Yale University School of Medicine, New Haven, CT). "But when the decision is to go with angioplasty, there are two findings: one is that the mean time is 21 minutes longer for patients presenting during off-hours, and the second is that the percentage of patients waiting more than two hours is greater. When patients are having a heart attack and every second counts, these are significant delays."

The results of the study are published in the August 17, 2005 issue of the Journal of the American Medical Association.

Speaking with heartwire, Krumholz explained that this study is one of a series they are conducting to understand the variation in time to reperfusion for acute MI and the factors associated with improving these times. The study is part of a large-scale effort to eliminate the delays in the time to reperfusion and to provide hospitals and clinicians with the information needed to improve their times. In this study, investigators sought to determine the pattern of door-to-drug and door-to-balloon times by time of day and day of week and whether this pattern affected mortality.

The data source for the retrospective study was the National Registry of Myocardial Infarction (NRMI), a voluntary prospective database of patients admitted with acute MI. The study cohort consisted of 68 439 patients with ST-segment-elevation MI treated with fibrinolytic therapy and 33 647 patients treated with PCI from 1999 to 2002. The primary outcome measure was reperfusion treatment time. Patient-arrival hours were categorized as either regular hours (weekdays from 7 am to 5 pm) or off-hours (weekdays from 5 pm to 7 am and weekends).

Investigators found that 67.9% of patients treated with fibrinolytic therapy and 54.2% of patients receiving PCI were treated during off-hours. Door-to-drug times were slightly longer during off-hours than regular hours, although the absolute time difference was small. Door-to-balloon times, on the other hand, were substantially longer during off-hours than during regular hours. Between 5 pm and 7 am and on weekends, the time to reperfusion for patients treated with PCI was more than 21 minutes longer.

"I think a lot of clinicians would agree that angioplasty, all things being equal, is better than lytic therapy," said Krumholz. "But all things being equal means that you can deliver both treatments rapidly, and this is clearly not what is going on right now. Off-hour angioplasty is often quite delayed."

Overall, after adjustment for patient covariates, patients presenting during off-hours had significantly higher in-hospital mortality than patients presenting during regular hours (odds ratio 1.07; 95% CI 1.01-1.14). The mortality difference was attenuated when adjustments were made for reperfusion treatment times, suggesting that the higher off-hours mortality was due in part to longer reperfusion treatment times.

Investigators also determined the proportion of patients receiving fibrinolytic therapy within the ACC/AHA guideline-recommended 30-minute door-to-drug treatment time and the proportion of patients receiving PCI within the guideline-recommended 90-minute door-to-balloon time. They found that a slightly lower proportion of patients received fibrinolytic therapy within 30 minutes during off-hours than during regular hours. For those receiving PCI, substantially fewer patients were treated within 90 minutes and more patients experienced prolonged door-to-balloon times (>120 minutes) during off-hours than during regular hours.

"What shouldn't be obscured by time of day or day of week is that the performance, with regard to time to reperfusion, is actually disappointing, both for PCI and fibrinolytics," said Krumholz. "More people are getting treated outside the guideline-suggested times than we would hope, even in the best possible scenario, which is during the day in the middle of the week when doctors are walking up and down the halls."

To see where the delays are occurring, Krumholz and colleagues examined the relationship between PCI treatment-time subintervals and patient-arrival hours. They found that during off-hours there was a significant increase in the time between when the data were collected and when the patient was sent to the cath lab. This increase in the time from ECG completion to arrival in the cath lab accounted for nearly all of the increased door-to-balloon times during this time.

Krumholz pointed out that the delays in treatment occurred in all types of hospitals, including large centers, teaching hospitals, and high-volume PCI centers. He said that allowing the emergency room to activate the cath lab, using paging systems to call multiple clinicians, and requiring those on call to live within a certain distance of the hospital are some ways to improve the time to reperfusion. Whatever means they choose to improve care, Krumholz said, hospitals must put systems in place that ensure a rapid response, where team members each have individual roles.

"What we want to see is that when a patient comes in with an ST-segment-elevation MI, the hospital and doctors are thinking that every second is precious and that they are prepared to execute a plan that has been put into place prior to the patient showing up on the front door," he said. "This way everybody knows their role and what is expected of them and we can fulfill the obligation of not having needless delays."