Aim: Long-term prognostic impact of coronary artery disease (CAD) severity in stable post-myocardial infarction (MI) patients is not well known. We examined the impact of CAD severity and co-morbidity on the long-term (1 year and beyond) risk of cardiovascular events post-MI.

Methods and results: From nationwide administrative and clinical registers, we identified 55 747 MI patients, during 2004-2010, who had not experienced subsequent MI, stroke, or death within 7 days post-discharge. The risk for primary composite endpoint (MI, stroke, or cardiovascular death) was estimated for the first 365 days after MI (index MI) and from day 366 to study completion (stable post-MI population), corresponding to a mean follow-up of 3.6 (2.2) years. Risk was assessed using cumulative incidence, multivariable adjusted logistic regression and Cox proportional-hazards models. The 1-year cumulative incidence for primary endpoint was 20.0% [95% confidence interval (CI), (19.6-20.3)]. Correspondingly, the 4-year cumulative incidence for primary endpoint was 21.0% (95% CI, 20.6-21.4) in patients without events on the first year. In multivariable models with no significant stenosis as reference, CAD severity was the most important risk factor for cardiovascular events the first 365 days [left main stenosis (LMS): odds ratio and 95% CI, 4.37, 3.69-5.17; 3-vessel disease (VD), 4.18, 3.66-4.77; 2-VD, 3.23, 2.81-3.72; 1-VD, 2.12,-1.85-2.43] and remained from day 366 to study completion [LMS: hazard ratio and 95% CI, 1.91, 1.64-2.22; 3-VD, 1.85,1.65-2.07; 2-VD, 1.55, 1.38-1.74; 1-VD, 1.30, 1.16-1.45].

Conclusion: Despite contemporary treatment at baseline, stable post-MI patients' 4-year outcome was similar to 1-year outcome after MI, and CAD severity remained a critical risk factor the first year and thereafter.