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Evidence-Based Treatments and Outcomes in NSTEMI Patients
Study Questions:
How did the implementation of evidence-based treatments of non-ST elevation myocardial infarction (NSTEMI) affect short- and long-term outcomes?
Methods:
The authors queried the SWEDEHEART (Swedish Web-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies) registry, which routinely collects information on patients hospitalized in the coronary care unit or with suspected acute coronary syndromes in all Swedish hospitals (n = 72). They included 205,693 cases with a diagnosis of NSTEMI from 1995-2014. Data from 1995-2001 mainly relied on elevations in creatine kinase-myocardial band (CK-MB) for the diagnosis of NSTEMI, while from 2001-2014, the diagnosis was based on the more contemporary criteria using troponin levels with either symptoms or electrocardiography. They examined outcomes, specifically all-cause mortality, cardiovascular mortality, MI, hospitalization for heart failure, and stroke over the 20-year study period divided into 2-year blocks, described differences in in-hospital therapies and discharge medications, and assessed the effect of time over the outcomes.
Results:
The authors reported a dramatic decrease in in-hospital mortality (from 12.4%-3.7%), cardiovascular mortality (11.7%-3.2%), and MI (2.7%-0.6%) over time. This improvement in outcomes is despite no significant change in the median age at presentation (74 years), the number of smokers (19%), and an increase in the proportion of patients with diabetes mellitus, hypertension, and previous revascularization. Concurrently, they noted an increase in the number of cases undergoing coronary angiography (1.9%-73.2%), percutaneous coronary intervention (4.8%-52.3%), and bypass grafting (1.7%-5.8%), in addition to major increases in Class I-recommended medication prescriptions. Their analyses suggest that the decrease in in-hospital outcomes was only partially attributed to the more frequent use of an early invasive strategy, while the reduction in 1-year outcomes is mostly explained by increasing implementation of an early invasive treatment strategy and guideline-based optimization of medical therapy.
Conclusions:
In this nationwide, registry-based study, cardiovascular outcomes and mortality in patients with NSTEMI improved dramatically over a 20-year period, largely due to the increasing implementation of an early invasive strategy and use of guideline-based medical therapy.
Perspective:
The authors state it well: “This study is a unique presentation of the development of treatments and outcomes in all patients with NSTEMI in an entire country during 20 years,” and represents compelling real-world evidence that guideline-based management works. The observational nature of the study precludes confirming that the improvement in outcomes is indeed due to the evolution in the management of NSTEMI; however, the close correlation between both over time, despite little change in relevant population characteristics, the corroboration with other reports, and the lack of alternative explanations make an excellent case for it. The effect size also may have been underestimated, as a proportion of cases labeled as NSTEMI are likely to have been secondary to noncardiac processes, and thus, did not benefit from NSTEMI-based treatments. Most importantly, the study shows no plateauing in the reduction of outcomes, suggesting that there is room for further improvements.
Clinical Topics: Acute Coronary Syndromes, Cardiac Surgery, Cardiovascular Care Team, Geriatric Cardiology, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Prevention, Aortic Surgery, Cardiac Surgery and Heart Failure, Acute Heart Failure, Interventions and ACS, Interventions and Imaging, Angiography, Nuclear Imaging, Hypertension, Smoking
Keywords: Acute Coronary Syndrome, Coronary Artery Bypass, Coronary Angiography, Creatine Kinase, MB Form, Diabetes Mellitus, Electrocardiography, Geriatrics, Guideline Adherence, Heart Failure, Hypertension, Myocardial Infarction, Myocardial Revascularization, Outcome Assessment, Health Care, Percutaneous Coronary Intervention, Smoking, Treatment Outcome, Troponin
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