Review of Emergency Department thrombolytic therapy and changes in inpatient mortality of acute myocardial infarction on the NSW Central Coast 1986 to 1994–96

AIMS: To examine changes in inpatient mortality of acute myocardial infarction (AMI) from 1986 to 1994-96 and to review the Emergency Department (ED) use of thrombolytic therapy (TT) for AMI on the NSW Central Coast. METHOD: A retrospective review of medical records of patients presenting to the EDs of Gosford and Wyong Hospitals with a discharge diagnosis of AMI (ICD9 code 410.x) from 1 January 1986 to 31 December 1986 and 1 January 1994 to 31 December 1996. Data were collected on patients' age, sex, duration of symptoms on arrival at the ED, ECG changes and presence of positive ECG criteria for thrombolysis, agent used, contraindications to TT, and inpatient mortality. The main measure of outcome was inpatient mortality. RESULTS: There were 423 admissions for AMI in 1986 and 1,220 admissions in 1994-96. The overall inpatient mortality has declined from 18.9% in 1986 to 9% in 1994-96 (p<0.0001). The mean age of patients has increased from 67.5 years to 68.1 years (p=0.35). The proportion of patients over age 75 years has increased significantly from 24.6% to 30.3% (p<0.0001). Presentation times from onset of symptoms have not changed significantly from a median time of two hours in 1986 to 2.5 hours in 1994 to 1996 (p=0.52). The overall proportion of patients with ECG criteria for TT was 53.2% in 1994-96. TT was administered to 42.9% of patients with a mean door to needle time of 67 minutes (median 45 minutes). The Australasian College for Emergency Medicine benchmark door to needle time of 60 minutes was achieved in 71.3% of patients. Streptokinase was the predominant agent given in 78%, while recombinant tissue plasminogen activator accounted for 15.7% of patients. Patients not receiving TT due to negative ECG criteria showed a decline in mortality from 18.6% to 6.7% (p<0.0001). Patients who underwent mechanical revascularisation (by bypass graft or angioplasty) increased from 8.7% to 17.4% (p<0.0001). Inpatient mortality has declined for all age groups, for both sexes, and for all sites of AMI. CONCLUSION: There have been significant declines in inpatient mortality of patients with AMI on the Central Coast. TT has had a significant impact on this decline but has an eligibility rate of less than half. Significant declines in mortality have also been seen in patients ineligible for thrombolysis. These patients have benefited from other therapies introduced or more widely used in the last decade. The results achieved on the Central Coast compare favourably with published reviews in Australia and overseas despite the lack of facilities for coronary angiography, coronary angioplasty and cardiothoracic surgery.