NEW ORLEANS — A mere 4% of U.S. acute MI patients transferred from one hospital to another for primary percutaneous intervention are treated within 90 minutes as recommended in recent guidelines, Brahmajee K. Nallamothu, M.D., reported at the annual scientific sessions of the American Heart Association.
This finding from the large National Registry of Myocardial Infarction (NRMI) database indicates an urgent need for improved process-of-care systems in order to minimize time delays for transferred MI patients, said Dr. Nallamothu of the University of Michigan, Ann Arbor.
The sense of urgency stems from the growing national and international momentum to widen the availability of primary percutaneous intervention. PCI, when performed expeditiously, yields outcomes clearly superior to thrombolytic therapy. But at present, only about 20% of U.S. acute care hospitals have the capacity to perform primary PCI.
When a patient presents to a hospital without such capacity, the only options are on-site thrombolysis or immediate transfer to another facility for the procedure. The pro-transfer argument is bolstered by several favorable European randomized controlled trials.
However, these trials were conducted in countries with better-organized care and shorter transfer distances than are the norm in the United States. As a result, total door-to-balloon times in the randomized trials—that is, the time delay between presentation at the first hospital and balloon inflation for primary PCI at the second—was only about 90 minutes. And the great majority of transferred American patients don't even come close to that speed of care.
Dr. Nallamothu's analysis of the NRMI-3 and -4 cohorts underscores that point. Of 4,278 consecutive acute MI patients transferred for primary PCI at 419 hospitals participating in the registry, only 4.2% had a door-to-balloon time of 90 minutes or less, as recommended in the recently issued AHA/American College of Cardiology guidelines (J. Am. Coll. Cardiol. 2004;44:671–719). The median door-to-balloon time was 180 minutes.
Only 16.2% of transferred patients had a door-to-balloon time of 120 minutes or less, as recommended in earlier AHA/ACC guidelines.
The great bulk of the time delay occurred because of prolonged transit times. More than 50% of transferred patients had transfer times in excess of 120 minutes.
Such delays may influence patient outcome. “The full benefits of primary PCI may not be realized in transfer patients until times to treatment are minimized,” Dr. Nallamothu said.
Beyond transit problems, several patient and hospital factors were also independently associated with prolonged total door-to-balloon times in a multivariate analysis. These included absence of chest pain, confusing ECG findings, prior coronary artery bypass surgery, arrival at the first hospital during off-hours, and presentation to a rural or nonteaching hospital.
Dr. Nallamothu said time delays would be greatly reduced if emergency departments in community hospitals that don't offer primary PCI set up efficient systems to promote early identification of patients with acute MI and promptly contact other facilities.
Another important measure will be to revise emergency medical services protocols so that in cases of suspected acute MI ambulances are encouraged proceed directly to the nearest hospital that offers primary PCI, bypassing closer hospitals that do not perform the service. Currently, most counties set up their own emergency medical services networks. In many locales, ambulance services are provided by a bewildering number of companies with minimal oversight, he added.
NRMI is an ongoing project funded by Genentech. Dr. Nallamothu's study was supported by the National Heart, Lung, and Blood Institute.