The long-term prognosis in patients with STEMI still requires improvement in the future. Different scales and factors predicting hospital and late outcomes have already been created [
5‐
8]. Most of the scales used in mortality prediction lack angiographic and procedural aspects [
9,
10]. One of the factors influencing the long-term efficacy of percutaneous interventions is the type of stent used for the procedure. Despite previous apprehension concerning drug-eluting stents (DES), they have turned out to be safe and efficient, also in the treatment of patients with acute coronary syndromes [
11]. DES have significantly limited restenosis, which potentially may improve the prognosis of patients; however, data concerning the influence of restenosis on the mortality are equivocal [
12,
13]. Nevertheless, it seems that the presence of coronary heart disease itself and its advancement are more important in the prognosis than the appearance of restenosis, which can be effectively treated today [
13]. We did not evaluate the influence of the type of stent on mortality in our study. However, there were no differences concerning the prevalence of DES in the compared groups (Table
1).
It should be borne in mind that disease affecting different segments and arteries may lead to diverse outcomes. The location of a lesion in the LAD could be of key importance in the prognosis of patients with STEMI, due to the fact that the occlusion of the proximal LAD is related to more extensive heart muscle damage and therefore worse outcomes [
10]. Nevertheless, the location of LAD occlusion did not present with differences in our analysis, which is also reflected in the lack of differentiation of the ejection fraction of the left ventricle, a direct exponent of the level of impairment of left ventricle. The Cx artery is the least frequent culprit vessel among patients treated invasively for STEMI [
3]. Furthermore, patients with Cx occlusion are less likely to present ST-segment elevation, hence they remain underdiagnosed. Nevertheless, it has not been established if the outcome differs depending on whether the stenosis is in the Cx or RCA, in patients with anterior STEMI treated invasively. In the presented study, we found that patients with Cx narrowing present with worse outcomes. The explanation for such an observation has not been clearly defined. Patients with LAD narrowing usually have collateral circulation from the RCA artery. Thus, RCA narrowing in patients with anterior STEMI should lead to worse compensatory backflow to the occluded LAD, affecting the outcome more than Cx stenosis. Moreover, some studies suggested that Cx-related STEMI is usually smaller compared with RCA-related STEMI [
14]. Such an observation should not be referred to the general population of patients with STEMI until coronary artery dominance is taken into consideration. Veltman et al. [
15] reported that the prognosis of STEMI patients during a 30-day follow-up is worse in the case of left coronary artery dominance. According to the cited observation, discrepancies in the prognosis may result from the dominance of one artery and not directly from the type of the artery—Cx or RCA. In the presented study, the prevalence of right dominance was similar in the two groups, hence it may not constitute an explanation for the differences in mortality. On the other hand, the differences in mortality may stem from the fact that Cx stenosis in patients with anterior STEMI can be interpreted as an equivalent of left main disease, leading to worse outcome. Nevertheless, all the patients in our study underwent staged PCI procedures and were fully revascularised. This is of key importance taking into consideration the debate on the justification of complete revascularisation in STEMI. The latest publications have shown that patients who underwent complete coronary revascularisation in the acute phase of STEMI have a better prognosis than the others [
16,
17]. These studies raise controversies, mainly due to the fact that the results are inconsistent with the results of large trials and meta-analyses [
18‐
21]. Newly presented and vastly discussed trials seem to only support the justification of complete revascularisation in patients with myocardial infarction regarding the aspect of the improvement of the prognosis. However, they do not report the optimal time of complete revascularisation. Undoubtedly, we will be provided with more information from large randomised ongoing trials, e.g. the COMPLETE study. In the presented study, staged revascularisation was performed during a period of 1 month in all the subjects. Consequently, it should not affect the differences in mortality between the groups. Regardless of such treatment, the prognosis of patients with Cx stenosis was worse. Poor outcomes of the Cx group of patients may finally result from missing ECG changes at the time of Cx reocclusion during the observation. This suggests that the 12-lead ECG alone is often not enough for the diagnosis of patients with suspected Cx occlusion or narrowing. According to the authors, this may stem from the fact that electrocardiographically asymptomatic Cx reocclusion during the follow-up could be more common than in the case of RCA. The issue refers to long-term follow-up and not only to the anterior infarction-related period. This may result from atherosclerosis progression, acceleration of the narrowing in already diseased vessels and finally myocardial ischaemia. Additionally, it may be caused by acute occlusion related to the atherosclerotic plaque rupture in that artery. However, these are only unconfirmed assumptions. Therefore, we should be aware of features of Cx occlusion other than ST-segment elevation, such as isolated ST-segment depression in precordial leads (the greatest in leads V2 and V3) [
22]. According to our findings, patients with anterior STEMI and Cx stenosis represent a group that requires a thorough evaluation during the follow-up period. Cx is a coronary artery requiring special attention because its stenosis in patients with anterior STEMI treated with PCI of the LAD leads to a worse prognosis in comparison with patients with RCA narrowing.
This study has a few limitations. First is the relatively small number of patients. However, to achieve a homogenous group of patients, we studied 3121 consecutive patients with STEMI. The observed correlation could be confirmed in the future with prospective and larger population studies. Moreover, we used overall mortality as an endpoint, due to the fact that it was not possible to define the cause of death in all cases. Thus, we are not certain whether all reported deaths were cardiovascular. Concluding, significant narrowing of the Cx leads to worse outcomes than narrowing of the RCA in patients with STEMI treated with PCI of the LAD. Thus, patients with Cx narrowing should be treated more cautiously and require special attention after anterior STEMI treated with PCI of LAD.