Prognosis after first-ever myocardial infarction in type 1 diabetes is strongly affected by chronic kidney disease

Objective: To study the prognosis after a first-ever myocardial infarction (MI) in type 1 diabetes, as well as how different MI- and diabetes-related factors affect the prognosis and risk of secondary cardiovascular events. 

Research Design and Methods: Observational follow-up study of 4,217 individuals from the Finnish Diabetic Nephropathy Study with no prior MI or coronary revascularization. We verified 253 (6.0%) MIs from medical records or death certificates. Mortality from cardiovascular or diabetes-related cause was our main endpoint, while hospitalization due to heart failure, coronary revascularization, and recurrent MI were secondary endpoints, while accounting for death as a competing risk.

Results: Of the individuals, 187 (73.9%) died during the median post-MI follow-up of 3.07 (IQR 0.02–8.45) years. Independent risk factors for cardiovascular and diabetes-related mortality were eGFR categories G3 (hazard ratio, HR 3.27 [confidence interval 1.76–6.08]), G4 (3.62 [1.69–7.73]), and G5 (4.03 [2.24–7.26]), prior coronary heart disease diagnosis (1.50 [1.03–2.20]), and older age at MI (1.03 [1.00–1.05]). Factors associated with lower mortality were acute revascularization (HR 0.35 [0.18–0.72]), and subacute revascularization (0.39 [0.26–0.59]). In Fine-Gray competing-risk analyses, kidney failure was associated with a higher risk of recurrent MI (subdistribution hazard ratio 3.27 [2.01–5.34]), heart failure (3.76 [2.46–5.76]), and coronary revascularization (3.04 [1.89–4.90]).

Conclusions: Individuals with type 1 diabetes have a high cardiovascular and diabetes-related mortality after their first-ever MI. Particularly poor kidney function is associated with high mortality and excessive risk of secondary cardiovascular events.