Anterior vs non-anterior ST-segment elevation myocardial infarction: incidence of reinfarction and target vessel failure
Authors: Sa Couto D , Alexandre A , Faria J , Luz A , Campinas A , Frias A , Santos R , Brochado B , Silveira J , Torres S 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background and purpose
Left anterior descending (LAD) coronary artery occlusion has been associated with worse short-term outcomes and overall worse prognosis, there is still unclear data about the long-term risk of reinfarction in relation to the index culprit vessel.

Methods
In this retrospective cohort study, between 2008 and 2013, a total of 584 patients were admitted with STEMI and were subject to emergent percutaneous coronary intervention (PCI). Of those, 535 (91.6%) were alive at hospital discharge, from which 532 were considered for the analysis, after excluding the missing cases. We stratified the individuals according to the culprit vessel in two groups: anterior myocardial infarction (MI) (LAD or left main stem (LM)), and non-anterior MI (circumflex (CX) or right coronary artery (RCA)). We followed the cases for a maximum of 8 years, censoring every event beyond. The primary endpoints were reinfarction and target vessel failure (TVF). Secondary endpoints included all-cause mortality, heart failure (HF) hospitalization and stroke. Mann-Whitney-U and Chi-square tests were used to compare baseline characteristics. Kaplan-Meyer survival analysis was used to obtain the survival curves. Univariate and multivariate analysis were done using Cox regression models.

Results
Of the 532 individuals included in the analysis, 395 (74.2%) were men and the median age was 61 (+/- 19.8) years. The most common culprit vessel was RCA (45.5%), followed by LAD (41.2%), CX (13.2%), and lastly LM (0.20%). The median follow-up time was 6.94 (+/- 2.38) years. Overall, the anterior MI group presented at a higher Killip class (20.0% vs 14.8% in Killip class II-IV; p = 0.046) and had higher peak plasma level of high-sensitivity troponin T (6.16 vs 3.66 ng/ml; p &lt; 0.001), suggesting larger infarct area. Left ventricle ejection fraction (LVEF) at discharge was also lower in the anterior MI group (reduced in 78,3% vs 43.4%; p &lt; 0.001). Multivessel disease was more common in the non-anterior MI group (49.5% vs 60.9%; p = 0.005), as was PCI of non-culprit vessels (15.5% vs 22.8%; p = 0.037) and the use of bare-metal stents (20.0 vs 51.6%; p &lt; 0.001). There were no significant differences between the groups regarding the main comorbidities, except for peripheral artery disease, more common in the non-anterior MI group (4.10 vs 10.0%; p = 0.011). There was a higher risk of reinfarction in the non-anterior MI group which persisted after relevant variable adjustment (Adjusted hazard ratio 1.96; 95% CI [1.08 – 3.67]; p = 0.027) (Figure 1). There were no significant differences regarding the risk of TVF or any of the secondary outcomes.

Conclusions
Although LAD/LM occlusion is thought to carry a worse short-term prognosis, non-anterior STEMI appears to be associated with a higher long-term risk of reinfarction. Despite higher rates of reinfarction, non-anterior STEMI patients have not been shown to have an excess mortality of HF hospitalizations in this cohort.