Relations between implementation of new treatments and improved outcomes in patients with non-ST-elevation myocardial infarction during the last 20 years: experiences from SWEDEHEART registry 1995 to 2014

Abstract

Aims: We assessed the changes in short- and long-term outcomes and their relation to implementation of new evidence-based treatments in all patients with non-ST-elevation myocardial infarction (NSTEMI) in Sweden over 20 years.

Methods and results: Cases with NSTEMI (n = 205 693) between 1995 and 2014 were included from the nationwide Swedish Web-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies (SWEDEHEART) registry. During 20 years in-hospital invasive procedures increased from 1.9% to 73.2%, percutaneous coronary intervention or coronary artery bypass grafting 6.5% to 58.1%, dual antiplatelet medication 0% to 72.7%, statins 13.3% to 85.6%, and angiotensin-converting enzyme inhibitors/angiotensin II receptor blocker 36.8% to 75.5%. The standardized 1-year mortality ratio compared with a control population decreased from 5.53 [95% confidence interval (CI) 5.30-5.75] to 3.03 (95% CI 2.89-3.19). If patients admitted the first 2 years were modelled to receive the same invasive treatments as the last 2 years the expected mortality/myocardial infarction (MI) rate would be reduced from 33.0% to 25.0%. After adjusting for differences in baseline characteristics, the change of 1-year cardiovascular death/MI corresponded to a linearly decreasing odds ratio trend of 0.930 (95% CI 0.926-0.935) per 2-year period. This trend was substantially attenuated [0.970 (95% CI 0.964-0.975)] after adjusting for changes in coronary interventions, and almost eliminated [0.988 (95% CI 0.982-0.994)] after also adjusting for changes in discharge medications.

Conclusion: In NSTEMI patients during the last 20 years, there has been a substantial improvement in long-term survival and reduction in the risk of new cardiovascular events. These improvements seem mainly explained by the gradual uptake and widespread use of in-hospital coronary interventions and evidence-based long-term medications.