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Risk factors for 'microsize' vs. usual myocardial infarctions in the REasons for Geographic and Racial Differences in
Zaid I Almarzooq1, Lisandro D Colantonio2, Peter M Okin3
1Division of Cardiovascular Medicine, Brigham and Women's Hospital, 75 Francis Street, Boston, MA, USA.
Aims:
A recently described phenomenon is that of myocardial infarction (MI) events that meet criteria for MI, but that have very low peak troponin elevations, so-called 'microsize MI'. These events are very common and associated with increased risk of all-cause mortality. Our aim is to compare risk factors for microsize MI vs. usual MI events.
Methods And Results:
Among 24 470 participants of the Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort free of coronary heart disease at baseline, heart-related hospitalizations were expert adjudicated for MI using published guidelines. Myocardial infarctions were classified as microsize MI (peak troponin <0.5 ng/mL) or usual MI (peak troponin ≥0.5 ng/mL). Competing risk analyses assessed associations between baseline risk factors and incident microsize vs. usual MI. Between 2003 and 2013 there were 891 MIs; 279 were microsize MI and 612 were usual MI. Risk factors for both usual MI and microsize MI include age, gender, diabetes, and urinary albumin to creatinine ratio. Risk factors for only usual MI include Residence in the Stroke Belt and Buckle regions and current smoking. Black race was associated with a uniquely lower risk of usual MI.
Conclusion:
The similarities in risk profiles suggest a possible common aetiology and should encourage clinicians to both treat reversible risk factors for microsize MI and to initiate secondary prevention strategies following these events until this emerging clinical entity is better understood. Future studies should further assess the clinical outcomes of these two entities and their effect on future management.
Insights
Microsize myocardial infarction (MI) shares risk factors with usual MI, including age, diabetes, and urinary albumin. Clinicians should manage reversible risk factors and initiate secondary prevention for microsize MI.
Area of Science:
- Cardiology
- Epidemiology
- Biomarkers
Background:
- Myocardial infarction (MI) with low peak troponin levels, termed 'microsize MI', is a common phenomenon.
- Microsize MI is associated with an increased risk of all-cause mortality.
- Understanding the distinct risk factors for microsize MI is crucial for effective management.
Purpose of the Study:
- To compare the risk factors associated with microsize MI versus usual MI.
- To identify specific risk factor profiles for each type of MI.
Main Methods:
- Analysis of 24,470 participants from the REGARDS cohort, excluding those with pre-existing coronary heart disease.
- Expert adjudication of heart-related hospitalizations to classify MIs as microsize (peak troponin <0.5 ng/mL) or usual (peak troponin ≥0.5 ng/mL).
- Competing risk analyses were used to assess associations between baseline risk factors and incident microsize vs. usual MI.
Main Results:
- A total of 891 MIs occurred between 2003-2013, with 279 classified as microsize MI and 612 as usual MI.
- Common risk factors for both microsize and usual MI included age, gender, diabetes, and elevated urinary albumin to creatinine ratio.
- Risk factors exclusive to usual MI were residing in the Stroke Belt/Buckle regions and current smoking. Black race was associated with a lower risk of usual MI.
Conclusions:
- The shared risk profiles suggest a potential common etiology between microsize and usual MI.
- Clinicians should address reversible risk factors and implement secondary prevention strategies for microsize MI.
- Further research is needed to elucidate the clinical outcomes and optimal management of microsize MI.