Impact of drug eluting stents’ length and diameter on short term outcome in patients undergoing primary percutaneous coronary intervention

Globally, acute myocardial infarction (AMI) is among the leading causes of death [1]. Primary percutaneous coronary intervention (PCI) should be used to conduct rapid reperfusion to secure the compromised myocardium [2]. Even though primary PCI produces faster and more reliable reperfusion with a lower risk of complications than thrombolysis [3], managing long coronary lesions remains difficult [4]. Patients with longer and smaller diameter bare metal stents (BMS) and first-generation drug eluting stents (1G-DESs) had a significantly greater incidence of major adverse cardiac events (MACEs) than patients with shorter and larger diameter BMS and 1G-DESs [5]. But there was not much information available on new generation DESs, particularly in primary PCI settings [5]. Regarding stent diameter, the risk of restenosis and other adverse cardiovascular events with BMSs has increased with smaller stent diameters [6]. When compared to BMSs, DESs have been demonstrated to lower the risk of in-stent restenosis (ISR) after PCI [7]. In this study, we aimed to assess the impact of second-generation drug eluting stents (2G-DESs) length and diameter on angiographic and MACE outcomes during in-hospital and short term (3 months’) follow up in STEMI patients undergoing primary PCI.

To evaluate the effect of 2G-DES length and diameter on angiographic and MACE outcomes in patients receiving primary percutaneous coronary intervention (PCI) during short-term and in-hospital follow-up.

patients with STEMI were enrolled in our prospective observational study. A prior PCI, an ectatic lesion, multi-vessel disease amenable to coronary artery bypass grafting (CABG), complicated lesions, including bifurcation lesions and left main (LM) stenting, or the presentation of Killip classes III and IV were among the exclusion criteria.

All the study population were subjected to the following: a complete history, a clinical examination, an ECG and 2D echocardiography (using Vivid 5e GE Healthcare machine), which used Simpson’s technique to assess systolic function. Segmental wall motion abnormalities (SWMA), mitral regurgitation (MR) severity (using both semiquantitative and quantitative methods) and diastolic function utilizing a tissue Doppler [8] were assessed prior to catheterization, prior to discharge and following a three-month period of follow up and laboratory examination (full blood count, lipogram, and renal function).

In this study, we present the impact of 2G-DESs length and diameter on angiographic and clinical outcomes in patients with STEMI undergoing primary PCI, including both in-hospital and 3-month follow ups.

Although 2G-DESs had advantages over 1G-DESs in terms of clinical outcomes and MACEs in STEMI patients [14–15], we discovered that longer stents were linked to higher odds of SF-NR, pre-dilatation requirements, mean procedure times and mean contrast amounts. Long stents had a greater incidence of recurrent ACS during the 3-month follow-up period, but there was no discernible difference in other MACE outcomes across the stent length groups.

Chen et al. observed similar findings linking longer stents to a higher risk of myocardial damage. This association may be explained by a higher risk of complication from distal embolization. Long stent implantation was more prone to stent under-expansion and mal apposition, thus increasing the need for balloon post-dilatation [16]. Nonetheless, the stent length factor had no effect on post-stent dilatation in our investigation. The higher frequency of pre-dilatation, which reduces the need for post-stent dilatation, could account for this.

The current investigation found a strong relationship between SF-NR and the number of pre-dilatations, as well as a correlation with longer procedure times, higher radiation doses, and higher amounts of contrast. Grade II Killip classification, more pre-dilatations, longer procedure time, lower EF (%), and diastolic dysfunction all significantly affected the incidence of SF-NR in a univariate logistic regression analysis. Only a greater number of pre-dilatations, however, had a significant impact on the incidence of SF-NR on multivariate analysis. It should be mentioned that stent diameter and length had no discernible effects on the incidence of SF-NR.

Lack of pre-dilatation before stenting may reduce the risk of clots, plaque content displacement and subsequent distant embolization [17], we found that the higher the number of pre-dilatations, the higher the incidence of SF-NR (p value 0.013).

Higher pre-procedural thrombus grade was found to be an independent predictor for the SF-NR phenomena during primary PCI, according to a report by Alidoosti et al [18]. As per our findings, individuals with severe thrombus burden (≥ grade 3) had a greater percentage of SF-NR (77.2%) compared to those without SF-NR (72.7%). Nevertheless, the difference was not statistically significant (P value = 0.409). The low number of patients in the SF-NR group or the overuse of thrombus aspiration could be the cause of this.

However, Stone et al. highlighted the significance of baseline TIMI flow, noting that patients with a TIMI flow of 3 at baseline and had a 0% death rate at the 6-month follow-up after reperfusion, while patients with lower initial TIMI flow had a 3.6% mortality rate [19]. The current study found that patients with pre-TIMI ≤ 2 had a greater incidence of SF-NR (81.8% vs. 70.4%) compared to patients without SF-NR, while the difference was not statistically significant (P value=0.252).

Killip classification > I was linked to no-reflow, according to Yu et al [20] & Zhou et al [21], both of whom reported similar results to this study. However, we have already eliminated the Killip III and Killip IV classes from our analysis.

Longer stents have been linked to ST and in-stent restenosis, which can result in long-term MACEs. Ejiri K et al. also noted that patients with stent lengths greater than 50 mm had a considerably higher risk of MACEs [22]. Consistent with these findings, we discovered that patients with longer stents had a higher incidence of recurrent ACS in the three-month follow-up (P=0.003), but there was no significant difference in terms of other MACEs. Analogous results from a single-center prospective registry revealed that stent length had no effect on the short- or long-term outcomes of patients implanted with DES, significantly reducing the effects of lesion length on ISR rates and MACE-free survival [23].

In the current investigation, we discovered that patients with lower EF (%), diastolic dysfunction grade 2, side branches occlusion, longer procedure times, longer door-to-device times, final TIMI flow grades ≤2, and grade II Killip classification were more likely to experience MACEs. While stent length and diameter were not linked to an increase in MACEs in univariate analysis, we did find that patients with grade II Killip classification and those who had longer procedure times had a higher likelihood of developing MACEs in multivariate analysis.

Crucially, at the baseline, in-hospital, and three-month follow-up periods, we were unable to detect any discernible differences between the groups of stent diameters (nor angiographic data, nor MACE outcomes). These findings are in line with those of Adnan et al, who found no conclusive correlations between DES’ length and diameter and any of the clinical outcomes [6].

Although 2G-DESs have made progress in reducing procedural complications and MACEs, stent-related variables continue to impact primary PCI results. With primary PCI, longer stents are linked to a higher incidence of SF-NR. Long stents are more likely to experience restenosis, which manifests as repeated re-vascularization during follow-up and recurrent ACS. However, stent diameter has no impact on outcomes in the presence of this new generation of DESs, which eliminates the effect of stent diameter on restenosis.

The study was approved by the ethical committee of Assiut University, Faculty of Medicine under IRB number (17100890), approval date (14.01.2020), consent for participation and publication was taken.