Treatment and outcome of myocardial infarction in hospitals with and without invasive capability. Investigators in the National Registry of Myocardial Infarction

Abstract

Objectives: We sought to determine the extent to which the capability of a hospital to perform invasive cardiovascular procedures influences treatment and outcome of patients admitted with acute myocardial infarction (AMI).

Background: Patients with AMI are usually transported to the closest hospital. However, relatively few hospitals have the capability for immediate coronary arteriography, percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass graft surgery (CABG), should these interventions be needed.

Methods: The 1,506 hospitals participating in the National Registry of Myocardial Infarction 2 were classified according to their highest level of invasive capability: 1) none (noninvasive, 28.1%); 2) coronary arteriography (cath-capable, 25.2%); 3) coronary angioplasty (PTCA-capable, 7.4%); and 4) bypass surgery (CABG-capable, 39.2%). Treatment and in-hospital outcomes were assessed for 305,812 patients admitted from June 1994 through October 1996. Follow-up through 90 days was ascertained in a subset of 30,402 patients enrolled simultaneously in both the National Registry of Myocardial Infarction (NRMI) 2 and the Cooperative Cardiovascular Project (CCP).

Results: The proportion of patients receiving initial reperfusion intervention was only slightly higher at the more invasive hospitals (noninvasive 32.5%, cath-capable 31.2%, PTCA-capable 32.9% and CABG-capable 35.9%, p < 0.001 by chi-square statistic). Among thrombolytic recipients, median door-to-drug time interval differed little among hospital types and ranged from 42 to 45 minutes. At cath-capable, PTCA-capable and CABG-capable hospitals, coronary arteriography was performed in 32.9%, 37.4% and 64.9%, respectively, and PTCA in 0.0%, 5.1% and 31.4%, both p < 0.001 by chi-square statistic. The proportion of patients transferred out to other facilities was 51.0%, 42.2%, 39.9% and 4.4% (p < 0.0001) among noninvasive, cath-capable, PTCA-capable and CABG-capable hospitals, respectively. Among patients in the combined NRMI and CCP data set, mortality at 90 days postinfarction was similar among patients initially admitted to each of the four hospital types.

Conclusions: Although patients with AMI admitted to hospitals without invasive cardiac facilities have a high likelihood of subsequent transfer to other facilities, their likelihood of receiving a reperfusion intervention at the first hospital, their door to thrombolytic drug intervals and their 90-day survival rates are similar to those of patients initially admitted to more invasively equipped hospitals. These data suggest that a policy of initial treatment of myocardial infarction at the closest medical facility is appropriate medical practice.