Long term survival after evidence based treatment of acute myocardial infarction and revascularisation: follow-up of population based Perth MONICA cohort, 1984-2005

Objective To examine trends in long term survival in patients alive 28 days after myocardial infarction and the impact of evidence based medical treatments and coronary revascularisation during or near the event. Design Population based cohort with 12 year follow- up. Setting Perth, Australia. Participants 4451 consecutive patients with a definite acute myocardial infarction according to the World Health Organization MONICA ( monitoring trends and determinants in cardiovascular disease) criteria admitted to hospital during 1984- 7, 1988- 90, and 1991- 3. Main outcome measures All cause mortality identified from official mortality records and the hospital morbidity data, with death from cardiovascular disease as a secondary end point. Results In the 1991- 3 cohort, 28 day survivors of acute myocardial infarction had a 7.6% absolute event reduction ( 95% confidence interval 4% to 11%) or a 28% lower relative risk reduction ( 16% to 38%), unadjusted for risk of death, over 12 years after the incident admission compared with the 1984- 7 cohort, similar to the survival of the 1988- 90 cohort. The improved survival for the 1991- 3 cohort persisted after adjustment for demographic factors, coronary risk factors, severity of disease, and event complications with an adjusted relative risk reduction of 26%( 14% to 37%), but this was not apparent after further adjustment for medical treatments in hospital and coronary revascularisation procedures within 12 months of the incident myocardial infarction. Conclusion The improving trends in 12 year survival after a definite acute myocardial infarction are associated with progressive use of evidence based treatments during the initial admission to hospital and in the 12 months after the event. These changes in the management of acute myocardial infarction are probably contributing to the continuing decline in mortality from coronary heart disease in Australia.