The Effect of Changing Diagnostic Algorithms on Acute Myocardial Infarction Rates
Introduction
Coronary heart disease (CHD), commonly manifest as acute myocardial infarction (AMI), is a major source of morbidity and mortality worldwide (1). Assessment of the incidence, prevalence and trends in AMI is critical to understanding this epidemic and explicit case definitions are essential methodologic tools. Historically, the World Health Organization (WHO) criteria form the basis for the diagnosis of an AMI case (2). Developed in the 1970s for European AMI registries, the WHO definition emphasizes classical symptoms, elevation in cardiac biomarkers, and electrocardiographic (ECG) changes. However, the WHO criteria are ambiguous, lacking precise definitions and are frequently misinterpreted (3). As a result of this ambiguity and advancing diagnostic technology, cardiovascular disease experts in the 1980s developed new criteria for AMI definitions with algorithms to better identify cases. These new criteria included efforts in the United States and Europe 4, 5.
Technological innovation in enzymes and other biomarkers in the late 1990s led to new demands for modification of the criteria. It was also apparent that the nature of the disease was changing and the classical Q-wave AMI was becoming less common with milder and more varied presentations emerging. The European Society of Cardiology (ESC) and American College of Cardiology (ACC) developed a new criteria set for clinical and research studies in 2000 (3). The new algorithm recognized modern biomarkers and the potential for imaging studies in the clinical and research settings. These criteria represented an advance but were developed for clinicians who needed to make the diagnosis in the acute clinical setting as opposed to retrospective studies where complete data are available 6, 7, 8. A 2003 workshop by the American Heart Association (AHA), World Heart Federation (WHF), and WHO developed criteria specifically for epidemiology studies and classification methods for developing countries where advanced diagnostic measures might not be available (9). In 2007, the ESC, ACC, AHA, and WHF proposed a new “universal definition of myocardial infarction” based on diagnostic advances in cardiology and concerns regarding the 2000 recommendations (10).
The current study examines the published criteria for diagnosing AMI using Minnesota Heart Survey (MHS) population-based data in 1995 and 2001 (11). We hypothesize rates for prevalence, incidence, and trends will differ significantly based on the diagnostic algorithm selected. In addition to evaluating the rates produced by the different algorithms, data are presented to quantify the impact of the newest biomarker, troponins, on AMI diagnosis.
Section snippets
Methods
Diagnostic algorithms for AMI include three basic elements: symptoms, biomarkers, and ECGs. The most advanced algorithms also include imaging techniques, such as computerized tomography and magnetic resonance imaging, but these are still rarely used in either clinical or epidemiologic applications 3, 10.
Six current algorithms are compared including: (1) MHS (11); (2) AHA/WHF/WHO (9); (3) ESC/ACC (3); (4) WHO (2); (5) monitoring of trends and determinants of cardiovascular disease (MONICA) (5);
Results
The population samples used to test the algorithms included 3197 cases in 1995 and 1617 cases in 2001. CK biomarkers were reported for all of the 1995 cases. In 2001, 748 (46%) patients had both troponin and CK measured.
Table 2 shows the 1995 hospitalization rates for definite AMI per 100,000 population using the six different published algorithms with and without the downgrade for muscle cutting procedures or trauma. The rates for men vary widely from 440/100,000 for the WHO standard to
Discussion
The accurate and rapid diagnosis of AMI has important therapeutic implications for clinicians, but consistent case definitions are critical for epidemiologists who seek to describe the epidemic and evaluate trends in incidence and prevalence (13). Research scientists must select from the various definitions to ensure consistent endpoints in clinical trials where previous AMI is used to select the target population, or, is an endpoint of the study. This study shows the dramatic effect of
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Fourth Universal Definition of Myocardial Infarction (2018)
2018, Global HeartCitation Excerpt :The standards described in this report are suitable for epidemiology studies and for international classification of diseases [199]. However, to analyse trends over time, it is important to have consistent definitions and to quantify adjustments when biomarkers or other diagnostic methods change [200], considering that the advent of cTn has dramatically increased the number of diagnosable MIs for epidemiologists [11,201]. In countries with limited economic resources, cardiac biomarkers and imaging techniques may not be available except in a few centres, and even the option of ECG recordings may be lacking.
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