Changes in drug treatment and case fatality of patients with acute myocardial infarction. Observations from the Newcastle MONICA Project, 1984/1985 to 1988/1990

Time trends in the treatment of acute myocardial infarction in Switzerland from 1986 to 1993: do they reflect the advances in scientific evidence from clinical trials?

Three acute coronary care surveys (1986, 1990, and 1993) were conducted in the Swiss region of Vaud-Fribourg on all men aged 25 to 64 years hospitalized for a definite myocardial infarction (218, 224, and 167 cases). Nearly all patients received anticoagulants and nitrates. The proportion of patients treated increased significantly, between 1986 and 1990, for antiplatelet drugs (from 51% to 96%) and thrombolytics (from 9% to 44%) and, between 1990 and 1993, for beta-blockers (from 57% to 78%) and angiotensin-converting enzyme inhibitors (from 26% to 43%). The use of calcium antagonists and antiarrhythmics dropped over time. Coronary arteriography and angioplasty were increasingly performed (53% and 18% in 1993), although progressively postponed in-hospital stay. The observed trends reflect a rapid translation of clinical trials into medical practice. However the use of thrombolytics could be raised further by shortening the hospitalization delay (median: 3 hours in 1993) and door-to-needle time (median: 47 minutes) which remained stable over time.

Trends in in-hospital mortality following acute myocardial infarction (AMI) in Victoria, 1987-1994

BACKGROUND

Death rates from coronary hearts disease have exhibited remarkable declines in most industrialised countries. Cardiovascular mortality has been the subject of extensive research and we considered it important to analyse recent local population based data on hospital outcomes of acute myocardial infarction (AMI).

AIM

To document the trends in in-hospital mortality from AMI in Victoria from 1987-1994.

METHODS

This was a retrospective analysis of data from the Victorian Inpatient Minimum Database relating to all public acute care hospitals. All separations recording a principal diagnosis 410 (AMI) were selected. Changes in distribution of AMI separations, in-hospital mortality, and changes in length of stay were examined.

RESULTS

The mean age of women admitted was 72 years compared with 64 years for men. Women comprised around a third of the overall sample but the proportion varied from 13% in those under 50 years to 57% among those aged 80 years and over. A striking decline in mortality was observed throughout the eight year period. The relative age adjusted decline was 33.5% (40% in males and 26% in females) with rates remaining higher in women. This decline occurred despite the increasing representation of those aged over 80 years. There was a significant decline in the mean length of stay (1.8 days) over the eight year period but this is likely to have had only minimal impact on mortality rates.

CONCLUSION

We have documented welcome declines in in-hospital mortality from AMI that are not an artefact of declining lengths of stay. Our observations parallel those in similar overseas studies. Large changes in medical management have taken place from the mid 1980s and may be partly responsible, but a change in disease process cannot be ruled out.

Decreasing mortality from acute myocardial infarctions: effect of attack rates and case severity

Mortality from myocardial infarction (MI) has declined in many countries and the reasons for the decline have not been fully quantified. We used the database of the Halifax County MONICA Project to test the hypothesis that the decline of in-hospital mortality from MI can be explained by a trend toward less severe disease as opposed to improved treatment. During the study period 1984-1993, 14,130 people aged 25-74 had been admitted to hospital with suspected MI. Of these, 3774 were diagnosed as definite MI by standardized criteria (480 fatal). For each patient, clinical history, serial cardiac enzymes, and ECG treatment regimen during hospital stay were extracted from patient charts. Survival status 28 days after onset of symptoms was determined. A severity index predicting 28-day case fatality was derived from health status at admission time. During the study period the rate of definite MI in the MONICA target population showed a general downward trend from 221 to 179 per 100,000/year (p = 0.0002). The severity index increased during the observation time (p < 0.0001), predicting 25% higher mortality. Case fatality fluctuated, but showed a marginally significant decline. We conclude that part of the decreased in-hospital mortality from MI is due to lower attack rates. The remainder occurred despite increased case severity and is possibly due to improved in-hospital treatment.

Women and Mexican Americans receive fewer cardiovascular drugs following myocardial infarction than men and non-Hispanic whites: the Corpus Christi Heart Project, 1988-1990

Mortality following myocardial infarction (MI) is greater among women than men and among Mexican Americans than non-Hispanic whites. Because therapy can affect mortality following MI, we examined differences in discharge therapy among these groups. Data regarding discharge therapy of 982 patients in the Corpus Christi Heart Project showed that women received fewer cardiovascular drugs than men, and Mexican Americans received fewer cardiovascular drugs than non-Hispanic whites. In multivariate analysis adjusting for age, cigarettes smoking, diabetes, hypertension, congestive heart failure, and serum cholesterol, the odds ratio for receipt of cardiovascular medications was 0.51 (95% CI: 0.28-0.93) for women versus men and 0.62 (0.3-1.15) for Mexican Americans versus non-Hispanic whites. Beta-blockers were prescribed rarely. Thus, treatment differences between ethnic and gender groups were observed following MI. Further research is needed to determine both the reasons for these differences and the extent to which these differences contribute to the observed survival patterns following MI.

Medical care and case fatality from myocardial infarction and coronary death in Newcastle and Perth

Coronary mortality rates are significantly higher in Newcastle than Perth. In this paper we examine the extent to which this might be due to differences in medical treatment and case fatality. Population-based disease registers were used to identify all cases of non-fatal definite myocardial infarction (MI) and coronary death in people aged 25-64 years in the study populations between July 1988 and June 1990. Case fatality (at 28 days from onset of symptoms) was not significantly different between the centres. Thrombolytic therapy was used for one third of all hospitalised events in both centres. Other drugs of proven benefit were, however, used more often in Perth than in Newcastle. For example, during hospitalisation 74% of patients in Perth received beta-blockers compared with 41% in Newcastle (difference = 33%, 95% confidence interval (CI): 28%, 37%) and 85% of patients in Perth compared with 72% in Newcastle received aspirin (difference = 13%, 95% CI: 9%, 17%). Median lengths of stay in a coronary care unit (CCU) and total hospital stay were one day shorter in Perth. As case fatality was similar, the differences in mortality rates can be attributed mainly to differences in attack rates. Greater use of cardio-active drugs in Perth apparently did not result in improved short-term outcome although potential long-term benefits cannot be judged yet.