The news emerging from data on 64,000 recent myocardial infarctions in the United States is not good. Life-and myocardium-saving thrombolytic therapy, it appears, has not been getting to patients as fast as it should be, and coronary care units are slowing down its delivery.
The information source is the National Registry of Myocardial Infarction, a commercially sponsored (Genentech Inc.) but independently managed (Clintrials, Lexington, Ky.) database of patients hospitalized for acute myocardial infarction between 1990 and the first half of 1992.
Analyses of data from over 800 participating hospitals presented at the American Heart Association 65th Scientific Sessions by W. Douglas Weaver, M.D., University of Washington, examined factor affecting duration of symptoms before admission and time to treatment.
WHO'S TREATED FIRST? Patients treated with thrombolytic therapy were younger (by about 8 years) and more likely to be male than those not receiving clot-busting agents. The median duration of symptoms prior to admission for all AMI patients was 2.2 hours.
The median was shorter (1.5 hours) for patients who ultimately received thrombolytic therapy than it was for those who did not (2.8 hours). Fifty-seven percent of patients were admitted within 3 hours of the onset of symptoms.
Time to treatment with thrombolytics after hospital admission spanned a wide range. Twenty percent of patients were treated in the first 30 minutes; another 38% were treated within an hour; an additional 20% from 60 to 90 minutes; and another 20% from 1.5 to 2.5 hours after hospital arrival.
Both duration of symptoms before admission and time to treatment after admission increased with the age of the patient. "This may suggest," Weaver said, "that the physician's decision to treat the elderly is more complex, and thus more time consuming." Time to treatment, while longer for both elderly men and women, was five to 10 minutes longer for women in younger age groups.
Time of day, Weaver reported, also affected these two parameters. Patients arrived at hospitals sooner after symptom onset in the late night hours, but it took longer in nighttime hours for them to receive treatment.
Although there were many individual variations within regions, analysis did reveal regional patterns. Hospital admission was most delayed after onset of symptoms in the mid-Atlantic and Southeastern states; time to treatment was longest in the Northeast and shortest in the South and West.
The 20% of patients who were given thrombolytic therapy in coronary care units received treatment an average of 25 minutes later than those treated in emergency rooms. "Some hospitals to make it a policy to administer thrombolytic therapy in the CCU instead of in the ER, and that's a big mistake. The delay occurs," Weaver speculated, "because of all the extra people who are involved in the physical transfer of patient and documentation, and the change in staff, both nurses and physicians."
Of the many statistically significant factors affecting time to treatment, the place of treatment (ER versus CCU) and treatment time of day were most influential. Still significant but less important were geographic region, age, and sex.
THE REAL CONCERN: The most disturbing finding, according to Weaver, was the lack of improvement in time to treatment. "Despite yours and my awareness of the need to initiate treatment as quickly as possible, the median time has changed a clinically insignificant amount--perhaps five minutes in the last two years," Weaver said. In addition, observational data suggest that 50% of patients wait 2.5 hours after onset of symptoms prior to getting to the hospital. "As shown in our Seattle prehospital program, hospital time of 30 minutes or less can be routinely achieved," Weaver said, "but it requires that in my hospital and yours, we evaluate each component of our delivery system and make interventions to reduce all performance delays in our time to treatment."
An American Heart Association poster presentation by Andrew J. Doorey, M.D., Hahnemann University, Philadelphia, suggested that expanded use of thrombolytic therapy through liberalizing restrictive eligibility criteria could save nearly 16,000 lives per year in the United States.
