Coronary thrombolysis: an important therapy for myocardial infarction

Changing patterns of medical treatment in acute myocardial infarction

TYPE OF STUDY

Descriptive study of trends in the drug therapy for acute myocardial infarction.

SETTING

Population-based register of acute coronary events compiled for the years 1984 to 1990 in the course of the Perth MONICA project.

CASES

5294 cases meeting clinical criteria for acute myocardial infarction.

RESULTS

Striking changes were seen in the use of aspirin before admission to hospital (from 4% to 18%). During the stay in hospital the use of beta-blockers increased steadily from 52% to 76%, while the use of aspirin increased 3.5-fold from 25% to 88% and the use of streptokinase increased 13.5-fold from 2.4% to 32.4%. The proportion of patients prescribed beta-blockers on discharge from hospital increased from 46% to 65% and that for aspirin rose from 16% to 83%. There were also major relative increases in the use of lipid-lowering agents and declines in the use of antiarrhythmic drugs.

CONCLUSION

These trends in the pharmacological management of myocardial infarction mirror the emerging evidence from clinical trials, although the increases in the use of certain types of drugs antedated publication of the results of major randomised studies. The changes in therapy would partly explain observed improvements in case fatality and may have contributed to the decline in coronary mortality observed in the Perth community.

Impact of a national educational campaign to reduce patient delay in possible heart attack

In 1989 the National Heart Foundation (NHF) of Australia's Heart Week campaign was directed towards encouraging those with symptoms of possible myocardial infarction (MI) to seek help as promptly as possible. To evaluate its effect, three surveys were conducted of patients admitted to 22 coronary care units (CCUs). Two (335 and 221 patients) preceded and one (253 patients) followed the public education campaign. During the third survey a subset of patients were asked why they delayed, how long they thought one should wait before seeking help, whether they were aware of the media campaign and whether this had influenced their behaviour. Overall, only 42% of 809 patients sought help within one hour (median delay 1.2 hours). The median time of arrival and the proportion of patients arriving within one, two and four hours was not altered after this campaign. Those who admitted to having been aware of the campaign sought help no more promptly. The Heart Week campaign could not be shown to have produced any clinically important change in patient delay. Future campaigns will need to be modified in the light of this experience.

Death from myocardial infarction: what are the benefits of early arrival at hospital and thrombolysis?

The potential benefits of early hospital care in the event of myocardial infarction were investigated in a community-based study of all suspected cases of heart attack among people aged under 70 years in the Hunter Region of New South Wales. Between August 1984 and December 1985 acute care data were collected for 1029 cardiovascular events classified as definite myocardial infarction or sudden coronary death; 516 (50%) resulted in death within 28 days from the onset of symptoms and 325 of these deaths (63%) occurred outside hospital. Of 703 people who are known to have reached hospital alive 205 (29%) did so more than four hours after the onset of symptoms. At the time of the study fewer than 1% of patients received streptokinase. To estimate the potential benefits of increased medical care an optimistic scenario was considered in which patients who arrived at hospital more than four hours after the onset of symptoms received medical attention earlier and all eligible patients received thrombolysis. Based on the results of the Second International Study of Infarct Survival (ISIS-2), if streptokinase and aspirin had been used 14% of deaths would have been averted. If, in addition, patients had arrived at hospital earlier and received optimal benefit from thrombolysis another 13% of deaths could have been avoided. These results provide a broader perspective of the potential benefits of improved medical care than can be obtained from hospital-based studies that deal only with those heart attack victims who survive long enough to reach hospital alive.