Summary
Background
Primary angioplasty with immediate stenting (IS) is the gold standard for ST-segment elevation myocardial infarction (STEMI). Deferred stenting (DS) has been proposed to limit periprocedural complications, and may influence stent size because of thrombus and spasm alleviation.
Aim
We sought to study the effect of DS on stent size.
Methods
Over the study period, 258 patients underwent primary angioplasty for STEMI (DS, n = 84; IS, n = 174). An informative coronary angiogram run – i.e. allowing for proper lesion analysis – was selected and anonymized by an independent operator. Two experienced operators randomly analysed these runs, and proposed stent dimensions after having measured vessel diameter and lesion length by quantitative coronary analysis. The primary objective was the variation in stent size between the two coronary angiograms.
Results
The median delay between the two coronary angiograms was 2 days. Overall, the stent length was shorter (–1.64 mm; P = 0.030) and its diameter was larger (+0.13 mm; P < 0.001) during the second coronary angiogram, especially in the right coronary arteries.
Conclusions
DS led to the implantation of a larger and shorter stent; this is probably because DS allows for more accurate assessment of the residual lesion after relief of spasm and thrombus, and may have clinical consequences in terms of stent thrombosis and restenosis.
Résumé
Contexte
L’angioplastie primaire avec stenting immédiat (SI) est le traitement de référence du syndrome coronarien aigu avec élévation du ST. La stratégie de « stenting différé » (SD) a été développée afin de limiter les complications péri-procédurales et pourrait influencer les dimensions du stent implanté du fait de la régression des phénomènes de spasme et de thrombose. La stratégie SD pourrait modifier la taille du stent implanté.
Objectif
Nous avons cherché à étudier l’effet de la stratégie SD sur la taille du stent.
Méthodes
Deux cent cinquante-huit patients pris en charge pour angioplastie primaire ont été inclus, 84 ont été traités par stratégie SD et 174 par la stratégie SI. Pour chaque patient, une séquence permettant l’analyse de la lésion avant stenting a été sélectionnée et anonymisée par un opérateur indépendant. Les séquences préalablement randomisées ont été analysées par 2 angioplasticiens afin de mesurer la lésion par Quantitative Coronary Assessment et de proposer une taille (diamètre, longueur) de stent. L’objectif principal était d’étudier la variation de dimensions des stents proposés entre les 2 coronarographies dans le groupe SD.
Résultats
Le délai médian entre 2 coronarographies était de 2 jours. La stratégie SD a conduit au choix de stents plus courts (–1,64 mm ; p = 0,030) et plus larges (+0,13 mm ; p < 0,001) lors de la seconde coronarographie, essentiellement pour les artères coronaires droites.
Conclusions
La stratégie SD permet de réaliser une angioplastie avec implantation de stents plus courts et plus larges. Ceci est probablement lié à une estimation plus précise de la lésion coupable après la levée du spasme coronaire et la réduction de la charge thrombotique intra-coronaire. Cela pourrait avoir un impact clinique en termes de resténose intra-stent et de thrombose.
Background
During primary percutaneous coronary intervention (PCI) in ST-segment elevation myocardial infarction (STEMI), immediate stenting (IS) in a thrombus-laden coronary lesion can lead to complications, such as distal embolization, no-reflow and acute stent thrombosis . Moreover, direct stenting may jeopardize optimal preparation of coronary lesions, which can lead to residual obstructive plaque, stent undersizing and malapposition , and increase the risk of restenosis and stent thrombosis .
In recent years, an emerging concept of deferred stenting (DS) has been proposed to minimize distal embolization into the microvasculature and, hopefully, to improve outcomes in STEMI . We have recently highlighted that in the presence of thrombolysis in myocardial infarction (TIMI) 3 flow, an important thrombotic thrombus burden identifies some patients in whom DS is of particular interest, with a decrease in risk of periprocedural events . A further potential advantage of DS, in addition to the immediate protective effects, is to allow for more accurate assessment of the residual stenosis after thrombus regression and spasm release. Consequently, DS may lead to better stent sizing, with a foreseeable bigger diameter and shorter length.
The aim of this study was to investigate the effect of DS on stent sizes through a blind comparison of lesion characteristics and stent proposals between the first and the second angiogram evaluation.
Methods
This was a retrospective analysis of patients with STEMI who were referred to our centre (Croix-Rousse Hospital, Lyon, France) over a 3-year period for primary PCI within 12 hours of symptom onset, with the culprit lesion in the left anterior descending (LAD), circumflex, right coronary (RCA) or left main artery. The diagnosis of STEMI comprised typical chest pain lasting > 30 minutes with persistent ST-segment elevation > 1 mm in two or more contiguous leads. Patients with left bundle branch block, stent thrombosis or previous coronary artery bypass surgery, or who had received thrombolysis were excluded. Patients were admitted directly to the catheterization laboratory in an emergency setting. A radial or femoral approach was used with a 6 Fr sheath to allow for potential thromboaspiration. An intracoronary injection of nitroglycerine was given in all patients after restoration of antegrade flow. Patients underwent an IS or DS strategy based on criteria developed in our previous work (i.e. TIMI 3 flow restoration, large thrombus burden, regression of chest pain and regression of ST-segment elevation). Patients undergoing IS had only one angiogram, while those who had DS had two angiograms separated by ≥ 24 hours, except in the case of a recurrence of ischaemic symptoms.
In accordance with French legislation, an observational study that does not change the routine management of patients does not need to be declared or submitted for approval to a research ethics board. Informed consent was obtained from all patients.
Study protocol
All patients in the DS group who had two films were included in the analysis, and constituted the main study group. Patients in the IS group (i.e. with one film) were also considered, because their films were included among the angiograms at the time of randomization, and thus prevented physicians from recognizing sequences, and they increased the number of angiograms used for the quantitative coronary analysis (QCA) quality check. Of note, the film analysis was performed a posteriori, and did not interfere with the management of the lesions or the choice of stent.
The analysis was conducted over a sequence of four steps. The variables collected by the operators are summarized in Fig. 1 .
Step one: run selection and randomization
For each coronary angiogram, a run with the culprit lesion was selected, anonymized and randomized by an independent physician (P. E.). The run was selected to allow for a satisfactory lesion analysis and a stent proposal. Finally, after the runs were randomized, using an informatics process, one run was studied for IS patients and two runs for DS patients.
Step two: vessel and lesion analysis
The randomized runs were analysed by QCA (Philips Xcelera, Best, Netherlands) by two independent operators (B. H. and E. C.) who were blinded to the strategy, the time-course and the patient’s medical history. The reference vessel diameter (RVD) and the length of the lesion were determined by each operator and averaged for the analysis.
Step three: stent proposal
For each analysis of the culprit lesion, a stent diameter and length (based on standard dimensions provided by the manufacturers) were proposed by the two operators and averaged for analysis. Again, this led to one stent proposal for patients in the IS group and two stent proposals (one for each coronary angiogram) for patients in the DS group.
Step four: QCA quality check
To validate the accuracy of the QCA measurements, each implanted stent was measured by QCA by an independent operator (P. E.) and compared with its nominal size.
Statistical analysis
Continuous variables are expressed as mean ± standard deviation (SD) or mean (95% confidence interval). Qualitative variables are expressed as absolute number and percentage. Univariate analysis was carried out using the χ 2 test for qualitative data and the t -test for quantitative data. Further analyses were conducted according to quartiles of initial RVD (Q1 < 2.47 mm; Q2 from 2.48 to 2.86 mm; Q3 from 2.87 to 3.10 mm; Q4 > 3.10 mm) and of lesion length (Q1 < 12.98 mm; Q2 from 12.99 to 16.82 mm; Q3 from 16.83 to 23.71 mm; Q4 > 23.71 mm). One-way analysis of variance was used for comparison. Correlations were assessed with Spearman’s test. Inter- and intraobserver reproducibilities were assessed for QCA by intraclass correlations in a subset of 15 patients selected randomly. Interobserver reproducibility was also tested using a Bland-Altman representation. A P value < 0.05 was considered as statistically significant. Analyses were performed using SPSS 20.0.0 software (SPSS, Chicago, IL, USA).
Results
A total of 258 patients were included in the study, 84 in the DS group and 174 in the IS group. This led to the randomization and analysis of 342 films (2 × 84 for DS and 174 for IS). The clinical characteristics of the patients are summarized in Table 1 . Patients in the DS group were more likely to be men, while no differences were apparent in terms of risk factors and STEMI location.
| Characteristic | All ( n = 258) | DS ( n = 84) | IS ( n = 174) | P a |
|---|---|---|---|---|
| Age | 61.99 ± 13.63 | 60.44 ± 12.85 | 62.74 ± 13.96 | 0.29 |
| Men | 191 (74.0) | 69 (82.1) | 122 (70.1) | 0.026 |
| History of CAD | 16 (6.2) | 6 (7.1) | 10 (5.7) | 0.43 |
| Hypertension | 91 (35.3) | 33 (39.3) | 58 (33.3) | 0.22 |
| Hypercholesterolaemia | 75 (29.1) | 24 (28.6) | 51 (29.3) | 0.50 |
| Smoking | 157 (60.9) | 48 (57.1) | 109 (62.6) | 0.22 |
| Diabetes mellitus | 32 (12.4) | 9 (10.7) | 23 (13.2) | 0.36 |
| Family history of CAD | 66 (25.6) | 20 (23.8) | 46 (26.4) | 0.38 |
| STEMI location | ||||
| Anterior | 101 (39.1) | 29 (34.5) | 72 (41.4) | 0.18 |
| Inferior | 134 (51.9) | 46 (54.8) | 88 (50.6) | 0.33 |
| Lateral | 42 (16.3) | 13 (15.5) | 29 (16.7) | 0.47 |
| Posterior | 16 (6.2) | 6 (7.1) | 10 (5.7) | 0.43 |
| Right ventricle extension | 2 (0.8) | 1 (1.2) | 1 (0.6) | 0.55 |
| Treatment | ||||
| Clopidogrel | 109 (42.2) | 32 (38.1) | 77 (44.3) | 0.21 |
| Prasugrel | 55 (21.3) | 19 (22.6) | 36 (20.7) | 0.42 |
| Ticagrelor | 94 (36.4) | 33 (39.3) | 61 (35.1) | 0.30 |
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