Relocation of minimal luminal diameter after bare metal and drug-eluting stent implantation: Incidence and impact on angiographic late loss

Clinical expert consensus document on quantitative coronary angiography from the Japanese Association of Cardiovascular Intervention and Therapeutics

Quantitative coronary angiography (QCA) remains to play an important role in clinical trials and post-marketing surveillance related to the safety and efficacy of new PCI devices. In this document, the current standard methodology of QCA is summarized. In addition, its history, recent development and future perspectives are also reviewed.

Acute and long-term relocation of minimal lumen area after bioresorbable scaffold or metallic stent implantation

AIMS

The aim of this study was to investigate relocation of minimal lumen area (MLA) after implantation of a bioresorbable scaffold (BRS).

METHODS AND RESULTS

In the ABSORB II randomised trial (BRS vs everolimus-eluting stent [EES]), lesions were investigated by serial intravascular ultrasound pre procedure, post procedure, and at three years. MLA relocation was defined as an axial MLA shift of more than 2.4 mm. MLA relocation from post procedure to three years was observed in 163/237 (68.8%) and 75/129 (58.1%) of lesions treated by BRS and EES, respectively (p=0.041). When matching preprocedural MLA site with the same topographical sites post procedure and at three years, BRS showed significant late lumen enlargement and expansive remodelling compensating for significant plaque increase, whereas EES showed significant late lumen narrowing with significant plaque growth not compensated for by expansive remodelling from post procedure to three years. In the multivariate analysis, female gender, previous PCI, BRS implantation, total device length, and maximal pressure (either at device implantation or post-dilatation) were independently associated with MLA relocation from post procedure to three years.

CONCLUSIONS

MLA relocation from post procedure to three years was more frequent in BRS than EES. Late lumen enlargement and expansive vessel remodelling at the preprocedural MLA site was observed in BRS, but not in EES.

Low resolution limits and inaccurate algorithms decrease significantly the value of late loss in current drug-eluting stent trials

Quantitative coronary and vascular angiography (QCA resp., QVA) remains the current gold standard for evaluation of restenosis. Late loss as one of the most commonly accepted parameters to highlight efficacy of the various devices has shown high correlation to clinical parameters but, surprisingly, has no impact on the evaluation of the remaining amount of restenostic tissue. The current clinical practice leads to unrealistic late loss calculations. Smaller late loss differences are usually not greater than the inherited resolution limits of QCA, which is especially the case in small differences between the various stents in the drug-eluting stent era. Late loss include additional systematic and random errors, due to the fact that measurements were taken at two different time points including the inherited resolution and calibration limits of QCA on two occasions. Due to the limited value of late loss in discriminating the small differences between the one and other DES, late lumen area loss and clearly defined calculation algorithms (e.g., MLD-relocation) should be used in future DES studies also to fulfill the more stringent regulatory requirements.

Impact of acute gain on clinical outcomes of patients treated with sirolimus-eluting stent. - A sub-analysis study from the STLLR trial-

BACKGROUND

Geographical miss (GM), representing suboptimal drug-eluting stent deployment, is associated with an increased risk of target lesion revascularization (TLR) and myocardial infarction. The impact of suboptimal stenting techniques on clinical outcomes in diabetics remains unknown.

METHODS AND RESULTS

Stent deployment Techniques on cLinicaL outcomes of patients treated with the cypheR(TM) stent (STLLR) is the first multicenter, large trial to prospectively evaluate outcomes associated with sirolimus-eluting stent (SES) deployment techniques. Axial GM and longitudinal GM (LGM), defined as a balloon injured segment or a diseased segment not covered by a SES, were assessed by an independent core laboratory. One-year outcomes between diabetics and non-diabetics and their relationship with GM were assessed. This substudy included 1,336 patients, 28.8% with diabetes. In non-LGM patients, TLR was similarly low in both diabetics and non-diabetics (2.0% vs. 2.0%, P=NS). However, TLR increased 4.1 times in diabetics (8.0%) and 1.9 times in non-diabetics (3.8%) in the presence of LGM (P=0.03). Axial GM had no impact on outcomes. By univariate analysis, stent length, acute gain, and LGM were the predictors of TLR in the total cohort. However, by multivariate analysis, acute gain was the only predictor of TLR (P=0.03), independently of LGM or diabetes.

CONCLUSIONS

Acute gain is the exclusive predictor of TLR after SES implantation. Particularly in diabetics, the negative impact of LGM on TLR seems to be amplified. Diligent SES deployment for larger acute gain is critical to improve clinical outcomes.

Clinical and angiographic outcomes after bare metal stents implantation for the patients with acute ST-elevation myocardial infarction: insights from multicenter trials

The general restenosis rate after emergent coronary stent implantation for ST-elevation myocardial infarction (STEMI) patients in Japan has yet to be fully established. Totally 696 STEMI patients without left main disease were enrolled for either ASPARAGUS (22 centers) or VAMPIRE (23 centers) trial. Out of these, 202 lesions in 202 patients with baseline and 6-month follow-up quantitative coronary angiography (QCA) data after emergent bare metal stent (BMS) implantation without either aspiration or distal protection devices were enrolled for this study. QCA was performed at an independent core laboratory. Minimal lumen diameter (MLD), reference diameter (RD) and diameter stenosis (DS) were estimated at pre, post and follow-up phase. Left ventricular ejection fraction was evaluated by quantitative left ventriculography. Six-month binary restenosis (DS >50%) rate and target lesion revascularization (TLR) were investigated. Six-month binary restenosis and TLR was found in 39 (19.3%) and 32 (18.6%), respectively. In the patients with binary restenosis, smaller pre-RD (2.46 ± 0.54 vs. 2.68 ± 0.73 mm, p = 0.03), post-MLD (2.08 ± 0.54 vs. 2.34 ± 0.52 mm, p = 0.009), acute gain (1.90 ± 0.49 vs. 2.13 ± 0.61 mm, p = 0.001) and follow-up RD (2.44 ± 0.67 vs. 2.71 ± 0.63 mm, p = 0.03) were observed. When the lesions are divided into quartiles of pre-RD (≤2.16, 2.18-2.61, 2.62-3.11, ≥3.12 mm), the binary restenosis rates were 26, 25.5, 16 and 10%, and TLR rate were 19.5, 29.6, 13.6 and 12%, respectively. RD was smaller at pre and follow-up than post phase (pre: 2.64 ± 0.71 mm; post: 2.89 ± 0.57 mm; follow-up: 2.66 ± 0.64 mm; pre vs. post: p < 0.001; post vs. follow-up: p = 0.001; pre vs. follow-up: p = 1.00). In this study cohort, the binary restenosis and TLR rate were considerable in patients with BMS for STEMI. The decrement of RD at follow-up period was common and it indicates that vessel shrinkage post PCI for acute myocardial infarction may be a myth. TLR rate was more than the binary restenosis rate in two quartiles of pre-RD. Robust guideline regarding stent type and revascularization for STEMI patients should be established.

Re-examining minimal luminal diameter relocation and quantitative coronary angiography--intravascular ultrasound correlations in stented saphenous vein grafts: methodological insights from the randomised RRISC trial

AIMS

Angiographic parameters (such as late luminal loss) are common endpoints in drug-eluting stent trials, but their correlation with the neointimal process and their reliability in predicting restenosis are debated.

METHODS AND RESULTS

Using quantitative coronary angiography (QCA) data (49 bare metal stent and 44 sirolimus-eluting stent lesions) and intravascular ultrasound (IVUS) data (39 bare metal stent and 34 sirolimus-eluting stent lesions) from the randomised Reduction of Restenosis In Saphenous vein grafts with Cypher stent (RRISC) trial, we analysed the "relocation phenomenon" of QCA-based in-stent minimal luminal diameter (MLD) between post-procedure and follow-up and we correlated QCA-based and IVUS-based restenotic parameters in stented saphenous vein grafts. We expected the presence of MLD relocation for low late loss values, as MLD can "migrate" along the stent if minimal re-narrowing occurs, while we anticipated follow-up MLD to be located close to post-procedural MLD position for higher late loss. QCA-based MLD relocation occurred frequently: the site of MLD shifted from post-procedure to follow-up an "absolute" distance of 5.8 mm [2.5-10.2] and a "relative" value of 29% [10-46]. MLD relocation failed to correlate with in-stent late loss (rho = 0.14 for "absolute" MLD relocation [p = 0.17], and rho=0.03 for "relative" relocation [p = 0.811). Follow-up QCA-based and IVUS-based MLD values well correlated in the overall population (rho = 0.76, p < 0.001), but QCA underestimated MLD on average 0.55 +/- 0.49 mm, and this was mainly evident for lower MLD values. Conversely, the location of QCA-based MLD failed to correlate with the location of IVUS-based MLD (rho = 0.01 for "absolute" values--in mm [p = 0.911, rho = 0.19 for "relative" values--in % [p = 0.111). Overall, the ability of late loss to "predict" IVUS parameters of restenosis (maximum neointimal hyperplasia diameter, neointimal hyperplasia index and maximum neointimal hyperplasia area) was moderate (rho between 0.46 and 0.54 for the 3 IVUS parameters).

CONCLUSIONS

These findings suggest the need for a critical re-evaluation of angiographic parameters (such as late loss) as endpoints for drug-eluting stent trials and the use of more precise techniques to describe accurately and properly the restenotic process.

Impact of stent deployment procedural factors on long-term effectiveness and safety of sirolimus-eluting stents (final results of the multicenter prospective STLLR trial)

Drug-eluting stent failures were associated with various clinical factors. However, the clinical impact of stent deployment technique was unknown. This study was designed to evaluate the frequency and impact of suboptimal percutaneous coronary intervention on long-term outcomes of 1,557 patients treated with sirolimus-eluting stents (SESs) in 41 US hospitals. All steps of the interventional procedure were scrutinized by an independent core laboratory to determine the occurrence of geographic miss (GM). GM included longitudinal (LGM; injured or diseased segment not covered by SES) or axial GM (balloon-artery size ratio <0.9 or >1.3) mismatches. Patients with and without GM were stratified (GM vs no-GM group). Patients, investigators, and the independent clinical event adjudication committee were blind to study group assignments. The primary end point was 1-year target-vessel revascularization (TVR) rate. Incidences and predictors of GM and safety outcomes were secondary end points. GM occurred in 943 patients (66.5%): 47.6% had LGM, 35.2% had axial GM, and 16.5% had both. One-year TVR rates were 5.1% in the GM group versus 2.5% in the no-GM group (p=0.025). TVR was 6.1% in the LGM versus 2.6% in the no-LGM subgroups (p=0.001). The association of GM with 1-year TVR was independent of clinical or anatomic factors (hazard ratio 2.0, 95% confidence interval 1.0 to 4.02, p=0.05). There was a 3-fold increase in myocardial infarction rates associated with GM (2.4% vs 0.8%; p=0.04). In conclusion, GM occurred frequently during SES implantation and was associated with increased risk of TVR and myocardial infarction at 1 year. These results emphasized the need for improvement in contemporary percutaneous coronary intervention practices and technologies.

Angiographic and 3D intravascular ultrasound assessment of overlapping bare metal stent and three different formulations of drug-eluting stents in patients with diabetes mellitus

OBJECTIVES

The aim of this study was to examine the impact of overlapping bare-metal stent (BMS) and three different formulations of drug-eluting stent (DES) on intimal hyperplasia (IH) response of patients with diabetes mellitus (DM).

METHODS

Forty-nine DM patients treated with overlapping BMS (19 lesions), sirolimus-eluting stent (SES 12 lesions), paclitaxel-eluting stent (PES 8 lesions) or tacrolimus-eluting stent (TES 10 lesions) were studied. Baseline and 9-month follow-up volumetric intravascular vascular ultrasound (IVUS) and quantitative coronary angiography (QCA) analysis were performed in the entire stented segment and in the overlapped (OL) and non-overlapped (non-OL) subsegments. Clinical outcomes were evaluated at 1-year follow-up.

RESULTS

Post-procedure (PO-) QCA measurements were similar in all stent groups, and between OL and non-OL subsegments in each individual type of stents. Percent IH was lower in SES and PES vs. BMS (p < 0.05). Percent IH was significantly greater in OL subsegment compared with non-OL subsegment in BMS (p < 0.05), but not in all type of DES groups. SES showed significantly less %IH compared with PES and TES in OL and non-OL subsegments. Vessel area at the OL remained unchanged from PO to FU in all type of DES and BMS groups. There were no aneurysm formation and no stent thrombosis up to 1-year follow-up.

CONCLUSIONS

Overlapping BMS is associated with enhanced IH response in diabetic patients, whereas overlapping DES, particularly SES and PES, appear effective to inhibit IH without detectable late vascular adverse effects.