Abstract
Background
Primary percutaneous coronary intervention (PCI) is the standard treatment in patients with ST-elevation myocardial infarction (STEMI). However, some patients still develop ST re-elevation during PCI, resulting in further myocardial damage and a poor outcome. An undersized-stenting approach may prevent ST re-elevation. We aimed to determine the association between final stent area and ST re-elevation during primary PCI for STEMI.
Methods
Overall, 102 consecutive STEMI patients who underwent primary PCI under integrated backscatter intravascular ultrasound guidance were enrolled. The stent–reference (SR) ratio was defined as the stent cross-sectional area (CSA) divided by the average CSA of the 5-mm proximal and distal reference lumens. The patients were divided into two groups according to the SR ratio: undersize group (SR < 1.0, n = 62) and oversize group (SR ≥ 1.0, n = 40). The incidences of ST re-elevation and total ST resolution (STR) were compared.
Results
The oversize group showed a higher incidence of ST re-elevation (32.5 vs. 9.7%, p = 0.004) and a lower total STR (22.4 ± 62.7 vs. 43.4 ± 38.6%, p = 0.04). After adjustment, the oversized-stenting approach was independently associated with ST re-elevation [odds ratio: 3.74, 95% confidence interval (CI) 1.27–12.1, p = 0.02]. The peak creatine kinase-MB level was higher in the oversize group (341 ± 259 vs. 242 ± 208 IU/l, p = 0.04). The incidences of stent thrombosis and restenosis were similar between the two groups.
Conclusions
An oversized-stenting approach in patients with STEMI was associated with a higher incidence of ST re-elevation and a lower total STR, resulting in increased myocardial damage.
Highlights
- •
The impact of final stent area size in ST-elevation myocardial infarction is unclear.
- •
We hypothesized that not-oversized-stenting approach may prevent further myocardial damage.
- •
Not-oversized-stenting approach achieved a higher total ST resolution.
- •
Oversized-stenting approach was an independent predictor of ST re-elevation.
- •
The peak creatine kinase-MB level was higher in oversized-stenting approach group.
1
Introduction
Primary percutaneous coronary intervention (PCI) is the gold standard treatment in patients with ST-elevation myocardial infarction (STEMI) . However, STEMI patients sometimes show ST re-elevation after primary PCI, resulting in major myocardial damage and poor outcomes. Many studies have attempted to resolve this limitation of primary PCI; however, the problem still persists and the issue has attracted attention for decades. The mechanical effect of stent deployment causes distal embolization induced by liberated plaque debris . Inadequate stent size may play a role in distal embolization or adverse events in STEMI patients; however, previous studies have not addressed the clinical effect of final stent size. Thus, there is still no guidance with respect to the final stent size during primary PCI, and it is always left to the operator’s discretion. An undersized-stenting approach may reduce distal embolization but may also cause stent thrombosis or restenosis. In contrast, an oversized-stenting approach may increase distal embolization but may reduce the incidence of stent thrombosis or restenosis. ST re-elevation and ST resolution (STR) are reliable markers of subsequent myocardial damage in STEMI and are strongly associated with clinical outcomes . We hypothesized that the final stent size, simply expressed as the ratio of stent area to reference lumen area (SR), would be associated with ST re-elevation and STR. The present study was conducted to assess the relationship between the SR ratio, ST re-elevation, and STR during primary PCI in STEMI patients.
2
Methods
2.1
Study protocol and patient enrollment
Our prospective acute coronary syndrome (ACS) registry was started in May 2011 and included all ACS patients who were admitted to Showa University Fujigaoka Hospital. Data in the present registry were collected from each case report and included complete details of the following: vital status, physical examination, medical history, complications, biochemistry tests, echocardiography, drugs at admission, drugs at discharge, in-hospital treatment, outcomes, and other data. The registry included a total of 681 ACS patients registered between May 2011 and May 2015. Intravascular ultrasound (IVUS) was routinely used during this period. Of the total cases, 197 consecutive STEMI patients who underwent primary PCI were screened. The inclusion criteria for the present study were as follows: 1) primary PCI was attempted within 24 h of symptom onset; 2) ongoing chest pain; and 3) > 0.1 mV ST-segment elevation from baseline in at least two contiguous leads on the 12-lead electrocardiogram (ECG). The exclusion criteria were as follows: 1) cardiopulmonary arrest; 2) a history of coronary artery bypass grafts; 3) left main trunk artery lesion; 4) restenosis lesion; 5) PCI without stenting; 6) more than 2 stents deployed; 7) no paired IVUS data with adequate quality before and after stent dilatation; and 8) ECG data inadequate to measure ST re-elevation.
All patients provided informed consent for the IVUS-guided primary PCI. The present study was reviewed and approved by the local institutional review board, and the study complied with the Declaration of Helsinki. All definitions, including coronary risk factors and cardiovascular events, conformed to the 2008 Key Data Elements and Definitions for Cardiac Imaging and Clinical End Points in Coronary Stent Trials compiled by the ACC/AHA/ACR/ASE/ASNC/HRS/NASCI/RSNA/SAIP/SCAI/SCCT/SCMR/SIR .
2.2
Primary PCI and IVUS procedure
All patients were given 200 mg of aspirin and 300 mg of clopidogrel (or 20 mg of prasugrel) immediately after the diagnosis of STEMI. These doses followed the guidelines of the Japanese Circulation Society . In the catheterization laboratory, an intravenous injection of 10 IU/kg heparin was given to maintain an activated clotting time of ≥ 300 s during the PCI procedure. Glycoprotein IIb/IIIa inhibitors were not used because they have not been approved in Japan. All patients underwent an IVUS examination using a 43-MHz integrated backscatter IVUS (IB-IVUS) catheter (View It, Terumo Co., Japan) immediately after wire crossing or thrombectomy. After administration of 2–3 mg of isosorbide dinitrate, continuous ultrasound images were acquired from the distal to the proximal segment of the lesion at an automated constant pullback rate of 0.5 mm/s. Decisions on thrombectomy, type of stent, stent diameter and length, pressure during deployment, and pre- and/or post-dilatation were left to the operators. The incidences of reperfusion injury defined as no-reflow phenomenon or arrhythmia during PCI were assessed. A final IVUS study was routinely performed at the end of the procedure. The incidence of no-flow, slow-flow, and side branch loss were assessed by angiography during PCI. When the patients showed no-flow or slow-flow phenomena, standard treatment such as additional aspiration and vasodilation were performed at the operator’s discretion.
2.3
IVUS measurement and data analysis
All IVUS imaging data were stored in the console (VISIWAVE; Terumo Co., Japan). For offline analysis, digital copies of the IVUS images were saved on hard disk drives. The tissue characteristics of plaque were analyzed with an offline computer-based software system (VISIATLAS; Terumo Co., Japan). A quantitative analysis of the IVUS data was performed according to the American College of Cardiology’s clinical expert consensus document .
The external elastic membrane and lumen cross-sectional area (CSA) were measured every 1 mm to assess the culprit lesion. Plaque area was calculated as external elastic membrane CSA minus lumen CSA. The volumes of the external elastic membrane, lumen, and plaque were calculated using Simpson’s rule. The volume index of each tissue (mm 3 /mm) was calculated as each tissue volume divided by the lesion length.
The analysis of the stents was performed by experienced analysts who were unaware of the angiographic findings and lesion characteristics, using a computer-based system (EchoPlaque 4.0; INDEC Systems, Inc., Santa Clara, California, USA). The CSAs of the external elastic membrane and lumen were measured in the proximal and distal reference segments, defined as 5 mm from the proximal and distal stent edges. When a significant side branch (with vessel diameter > 2 mm) was observed, the reference segment was closer than 5 mm to the stent edge. The average of the CSA measurements in the 5-mm proximal and distal reference segments was recorded as the average reference CSA. The stent CSA was measured every 1 mm, and the stent volume was calculated using Simpson’s rule. The stent area used for the SR ratio was measured at the segment with plaque rupture or the minimum CSA of the culprit lesion because plaque debris from the culprit lesion can cause distal embolism . The SR ratio was defined as the stent CSA in the culprit lesion divided by the averaged reference CSA ( Fig. 1 ). SR ratios using the minimum and maximum stent CSA and the stent volume/reference ratio were also assessed in relation to ST re-elevation. The stent volume index (mm 3 /mm) was calculated as stent volume divided by stent length.
