Incident MI and Very Late Stent Thrombosis in Stable CAD
What is the residual risk of myocardial infarction (MI), together with relevant associated factors, and related mortality, in stable coronary artery disease (CAD) outpatients?
The investigators analyzed data from the multicenter CORONOR registry, which enrolled 4,184 unselected outpatients with stable CAD (i.e., MI and/or coronary revascularization >1 year previously). Five-year follow-up was achieved for 4,094 (98%) patients and is the focus of this analysis. Incident MI, coronary revascularization, and the cause of death were adjudicated by two investigators with a third opinion in cases of disagreement. Univariate and multivariate assessments of baseline variables associated with incident MI were performed using competitive risk regression with death as a competing event.
The investigators identified a linear risk of incident MI (0.8% annually), with ST-segment elevation MI (STEMI) constituting one-third of all cases. Current smoking, low-density lipoprotein cholesterol, multivessel CAD, diabetes with hemoglobin A1c >7%, and persistent angina were all associated with increased risk, and prior bypass surgery with decreased risk. When used as a time-dependent variable, incident MI was associated with an increased risk of death (hazard ratio [HR], 2.05; p < 0.0001). Among patients with prior stent implantation, very late stent thrombosis (VLST) was causal in 20% of MI cases, and presented more often as STEMI versus MI not related to a stented site (59% vs. 26%, p = 0.001). Adjusted mortality was four times higher in patients with VLST versus MI not related to a stented site.
The authors concluded that in stable CAD outpatients, incident MI occurs at a stable rate of 0.8% annually and is related to VLST in one-fifth of cases.
This study reports that patients with stable CAD have a linear risk of MI of 0.8% per year in contemporary practice, and that a significant proportion of MI is related to VLST with important prognostic implications. In fact, VLST was frequently associated with STEMI, and predicted a higher risk of death. This study highlights multivessel CAD and other uncontrolled risk factors as variables associated with recurrent events, and underscores the need for intensive risk factor modification to mitigate this risk.
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