NEW ORLEANS — When thrombolysis fails to fully unblock the infarct‐related artery of a patient with an acute myocardial infarction, percutaneous coronary intervention is the best next step, according to the results of a controlled study with 427 patients.
Up to now, some physicians have treated MI patients who failed thrombolysis with percutaneous coronary intervention (PCI) because they intuitively believed that it was the right thing to do, but there was no evidence to back it up, Anthony H. Gershlick, M.B., said at the annual scientific sessions of the American Heart Association.
About 40% of patients who are treated with thrombolysis for an acute MI fail this initial treatment and do not show full resolution of their ST‐segment abnormality, said Dr. Gershlick, a cardiologist at University Hospital in Leicester, England. The results of the new study “tell us that you need to assess patients 90 minutes after thrombolysis with ECG to see if thrombolysis was successful.”
“These results should have an impact on practice,” commented Eric R. Bates, M.D., a professor of internal medicine at the University of Michigan in Ann Arbor. Community hospitals that use thrombolysis but lack a catheterization laboratory will need to collaborate with an angioplasty center that can treat their patients who fail thrombolysis, Dr. Bates said.
The study was done at 35 United Kingdom hospitals. Patients with an acute MI who received standard lytic therapy and aspirin underwent a repeat ECG 90 minutes after receiving their initial thrombolytic drug. (About 60% of patients received streptokinase, 27% received reteplase, and the remaining patients received other agents.) Patients with less than 50% resolution of their ST changes were randomized to one of three treatment strategies: conservative management in the hospital, repeat treatment with thrombolysis, or PCI (about 69% of the PCI‐treated patients received coronary stents).
The study's primary end point was the incidence of death, repeat MI, stroke, or severe heart failure at 6 months after treatment. This end point occurred in 15% of the 144 patients treated with PCI, 30% of 141 patients treated with conservative therapy, and 31% of 142 patients treated with repeat thrombolysis, a statistically significant difference in favor of PCI. PCI led to consistent reductions in death, repeat MI, and severe heart failure. Stroke incidence was similar in all three groups.
Treatment with PCI also led to a higher rate of major bleeding events, 19%, compared with 5% in the repeat lysis group and 2% in the conservatively managed group. Of the 27 patients with major bleeds in the PCI group, 22 cases involved sheath complications during coronary catheterization. The incidence of severe complications from bleeding were similar in the three groups.
The average time from the onset of pain to when patients received their first thrombolytic treatment was 140 minutes. Patients who received a second dose of a lytic drug got it an average of 190 minutes later; patients who received PCI were treated an average of 274 minutes later, an average delay of 84 minutes beyond the thrombolytic group.
Thus, the patients treated by rescue PCI got their definitive treatment nearly 7 hours after onset of chest pain. Despite this long delay to definitive treatment, these patients still did better than the comparator groups, Dr. Gershlick said.