Comparison of incidence patterns and risk profiles of ST-elevation and non-ST-elevation myocardial infarction in type 1 diabetes in Finland: a nationwide cohort study.

BACKGROUND

The incidence and risk profiles of ST-elevation myocardial infarction (STEMI) and non-ST-elevation myocardial infarction (NSTEMI) are understudied in type 1 diabetes. We aimed to study the similarities and differences in the incidence and risk profiles of myocardial infarction subtypes in people with type 1 diabetes.

METHODS

This prospective, multicentre cohort, the FinnDiane Study includes adults with type 1 diabetes, with no previous history of myocardial infarction or coronary revascularisation. Standardised age-specific, sex-specific, and complication-specific incidence rates of myocardial infarction subtypes STEMI and NSTEMI were calculated in Fine and Gray competing risk analyses. The risk profiles were assessed with Cox regression and Fine and Gray competing risk models.

FINDINGS: 4215 adults with type 1 diabetes who were enrolled in the Finnish Diabetic Nephropathy Study between Nov 21, 1997, and Dec 31, 2012, were included in this study. We verified 449 first-ever clinically recorded myocardial infarctions, including 84 (19%) STEMIs and 297 (66%) NSTEMIs, from medical records and death certificates between 1997 and 2017. The 20-year cumulative incidence was 15·4% (95% CI 12·0-19·1) for all myocardial infarctions, 2·4% (1·9-2·9) for STEMI, and 10·9% (7·8-14·6) for NSTEMI, with no differences by sex, but increasing with older age, particularly for NSTEMI. Compared with the reference period between 1997 and 2002, the incidence of STEMI decreased, while after an initial decline, NSTEMI incidence increased during follow-up. Older diabetes onset age, increased LDL cholesterol, reduced HDL cholesterol, severe diabetic retinopathy, severe albuminuria, and kidney replacement therapy were associated with increased risk of NSTEMI, but not of STEMI. Conversely, moderately and severely decreased eGFR were associated with increased risk of STEMI, but not of NSTEMI. Longer duration of diabetes, higher HbA1c, and current smoking were associated with increased risk of both myocardial infarction subtypes.

INTERPRETATION: We report that STEMI and NSTEMI exhibit different incidence patterns depending on age and year of myocardial infarction. STEMI and NSTEMI also differed regarding risk profiles, demonstrating that myocardial infarction risk assessment involves a complex interplay between multiple risk factors in type 1 diabetes.

FUNDING: Folkhälsan Research Foundation, Wilhelm and Else Stockmann Foundation, Liv och Hälsa Society, Sigrid Jusélius Foundation, State funding for university-level health research by Helsinki University Hospital, Medical Society of Finland, Diabetes Research Foundation, and Finnish Foundation for Cardiovascular Research.