Usefulness of intravascular ultrasound in preventing stenting of hazy areas adjacent to coronary stents and its support of support spot-stenting

The angiography-guided spot versus entire stenting in patients with long coronary lesions trial: Study design and rationale for a randomized controlled trial protocol

Background

/Purpose: Long-stenting, even with a second-generation drug-eluting stent (DES), is an independent predictor of restenosis and stent thrombosis in patients with long coronary lesions. Spot-stenting, i.e., selective stenting of only the most severe stenotic segments of a long lesion, may be an alternative to a DES. The purpose of this study is to compare the one-year clinical outcomes of patients with spot versus entire stenting in long coronary lesions using a second-generation DES.

Method

This study is a randomized, prospective, multi-center trial comparing long-term clinical outcomes of angiography-guided spot versus entire stenting in patients with long coronary lesions (≥25 mm in length). The primary endpoint is target vessel failure (TVF) at 12 months, a composite of cardiac death, target vessel-related myocardial infarction, and target vessel revascularization (TVR). A total of 470 patients are enrolled for this study according to sample size calculations. This study will be conducted to evaluate the non-inferiority of spot stenting compared to entire stenting with zotarolimus-eluting stents (ZES).

Results

This study is designed to evaluate the clinical impact of spot-stenting with ZESs for TVF due to possible edge restenosis or non-target lesion revascularization. Theoretically, spot-stenting may decrease the risk of TVR and the extent of endothelial dysfunction.

Conclusion

This SPOT trial will provide clinical insight into spot-stenting with a current second-generation DES as a new strategy for long coronary lesions.

Electrical Conductance Device for Stent Sizing

The minimum stent area (MSA) has been clinically established as a significant predictor of restenosis, thrombosis, and ischemia using intra-vascular ultrasound (IVUS). Unfortunately, IVUS measurements are far from routine because of significant cost of IVUS, the training required, the subjectivity of image interpretation and the time added to the procedure. The objective of this study is to verify the accuracy of a conductance catheter for stent sizing. Here, we introduce an easy and entirely objective device and method for real time determination of MSA. A 10 kHz, 35 μA rms current is passed through the external electrodes of an intravascular catheter while the conductance is measured across a separate set of electrodes. Both phantom and ex vivo validations of metal stent sizing in five porcine carotid arteries were confirmed. The accuracy of the measurements were found to be excellent in phantoms (root mean square, rms, of 3.4% of actual value) and in ex-vivo vessels (rms = 3.2% of measured value). An offset of conductance occurs when a conductive metal stent (e.g., bare metal stent) is deployed in the vessel, while the slope remains the same. This offset is absent in the case of drug eluting stent where the metal is coated (i.e., insulated) or non-metal bioresorbable stent. The present device makes easy, accurate and reproducible measurements of the size of stented blood vessels within 3.2% rms error. This device provides an alternative method to sizing of stent (i.e., MSA) in real-time without subjective interpretation and with less cost than IVUS.

Impact of the stent length on long-term clinical outcomes following newer-generation drug-eluting stent implantation

Stent length has been considered an important predictor of adverse events after percutaneous coronary intervention, even with the first-generation drug-eluting stents (DESs). The introduction of newer-generation DES has further reduced the rates of adverse clinical events such as restenosis, myocardial infarction, and stent thrombosis. The aim of this study was to compare the impact of stent length on the long-term clinical outcomes between first- and newer-generation DESs. The effects of stent length (≥32 vs <32 mm) on the clinical outcomes were evaluated in 8,445 patients who underwent percutaneous coronary intervention using either a first-generation DES (sirolimus- and paclitaxel-eluting stents, n = 6,334) or a newer-generation DES (everolimus- and zotarolimus-eluting stents, n = 2,111) from January 2004 to December 2009. The 3-year adverse outcomes (composite of all-cause death, nonfatal myocardial infarction, target vessel revascularization, and stent thrombosis) were compared using the inverse probability of treatment-weighted method according to the stent length. After adjustment for differences in the baseline risk factors, a stent length of ≥32 mm was significantly associated with higher cumulative rates of target vessel revascularization and stent thrombosis in the patients treated with a first-generation DES (adjusted hazard ratio 1.875, 95% confidence interval 1.531 to 2.297, p <0.001; adjusted hazard ratio 2.964, 95% confidence interval 1.270 to 6.917, p = 0.012), but it was not associated with the clinical outcomes in patients treated with a newer-generation DES. In conclusion, stent length might not be associated with long-term clinical outcomes in newer-generation DES era, whereas stent length might be associated with long-term clinical outcomes in the first-generation DESs.

Utility of optical coherence tomography to assess a hazy intracoronary image after percutaneous coronary intervention

Although its use in daily practice is not common, optical coherence tomography (OCT) is a powerful research tool in invasive cardiology. This report describes a hazy angiography image after percutaneous coronary intervention that has been assessed using OCT. Based on the results of the OCT, the patient underwent an elective coronary angioplasty with standard anticoagulation. After implantation of the stent, an intracoronary hazy image was seen on angiography. The use of OCT permitted a correct diagnosis and a successful treatment. This paper provides a discussion of the advantages and disadvantages of OCT, and a comparison with intravascular ultrasound.

Assessment of three dimensional quantitative coronary analysis by using rotational angiography for measurement of vessel length and diameter

The aim of the study was to assess the accuracy of the three-dimensional (3D) quantitative coronary analysis (QCA) system by comparing with that of intravascular ultrasound (IVUS) QCA and two-dimensional (2D) QCA. 3D QCA, 2D QCA and IVUS QCA were performed in 45 vessel segments. The obtained values for the branch to branch segment vessel length and the proximal part of the segment vessel’s lumen diameter were measured. Inter-technique agreement was analyzed using paired sample t-test and Bland–Altman analysis. No differences were found in vessel lengths taken by 3D QCA and IVUS QCA (mean difference: 0.29 ± 1.06 mm, P = 0.07). When compared with IVUS QCA, 2D QCA underestimated vessel length (mean difference: −1.78 ± 2.55, P < 0.001). Bland–Altman analysis showed close agreement and a small bias between 3D QCA and IVUS QCA in the measurement of vessel length. The vessel lumen diameter measurements by 2D QCA and 3D QCA were significantly lower than that by IVUS QCA (mean difference: −0.64 ± 0.69, P < 0.001; −0.56 ± 0.52, P < 0.001 respectively). Rotational angiography with 3D reconstruction can provide a more accurate vessel length measurement, whereas 2D and 3D QCA underestimated the vessel lumen diameter compared with IVUS QCA.

Comparison of long versus short ("spot") drug-eluting stenting for long coronary stenoses

We compared spot drug-eluting stenting (DES) to full stent coverage for treatment of long coronary stenoses. Consecutive, consenting patients with a long (>20 mm) coronary lesion of nonuniform severity and indication for percutaneous coronary intervention were randomized to full stent coverage of the atherosclerotic lesion with multiple, overlapping stenting (full DES group, n = 90) or spot stenting of hemodynamically significant parts of the lesion only (defined as diameter stenosis >50%; spot DES group, n = 89). At 1-year follow-up, 14 patients with full DES (15.6%) and 5 patients (5.6%) with spot DES had a major adverse cardiac event (MACE; p = 0.031). At 3 years, MACEs occurred in 18 patients with full DES (20%) and 7 patients (7.8%) with spot DES (p = 0.019). Cox proportional hazard model showed that the risk for MACEs was almost 60% lower in patients with spot DES compared to those with full DES (hazard ratio 0.41, 95% confidence interval 0.17 to 0.98, p = 0.044). This association remained even after controlling for age, gender, lesion length, and type of stent used (hazard ratio 0.42, 95% confidence interval 0.17 to 1.00, p = 0.05). In conclusion, total lesion coverage with DES is not necessary in the presence of diffuse disease of nonuniform severity. Selective stenting of only the significantly stenosed parts of the lesion is an appropriate therapeutic alternative in this setting, offering a favorable clinical outcome.

Intravascular Ultrasound in the Current Percutaneous Coronary Intervention Era

The use of intravascular ultrasound (IVUS) in the cardiac catheterization laboratory has continued to evolve since its introduction nearly 15 years ago. In this review, the authors discuss the current strategies regarding the use of this imaging modality during percutaneous coronary interventions. Although routine IVUS guidance of interventions is unnecessary, the tomographic perspective provided by this modality can be very informative in selected cases. It remains unknown whether the use of emerging IVUS-based technologies such as elastography or spectral analysis is feasible for identification of vulnerable plaques.

Coronary disease morphology and distribution determined by quantitative angiography and intravascular ultrasound--re-evaluation in a cooperative multicenter intravascular ultrasound study (COMIUS)

Although previous studies have demonstrated that even quantitative coronary angiography (QCA) can not provide accurate disease morphology, there has not been a systematic comparison of disease morphology determined by QCA and intravascular ultrasound (IVUS), particularly in Japanese patients. Therefore, the present study prospectively examined patients in a multicenter cooperative study. A total of 491 coronary sites from 562 patients (446 men, 116 women; mean age, 64+/-11 years) who underwent coronary interventions were enrolled. The target lesions (>50% diameter stenosis) were evaluated pre-operatively by both QCA and IVUS operating at 30-40 MHz and the percent area stenosis, eccentricity index (EI) and lesion length were determined. The minimal (min) and maximal (max) distances from the center of the stenotic lesion to the outline of the vessel wall were measured, and the EI was calculated by the formula: [(max - min)/max]. By QCA, lesion length was determined by measuring the distance between the proximal and distal shoulders of the lesion. When the lesions were observed by IVUS with a motorized pull-back system, the length was calculated by multiplying the time for observation of the disease and 0.5 or 1 mm/s. Although the severity of the stenosis determined by QCA (86+/-10%, mean +/- SD) did not differ from that by IVUS (83+/-13%), there was no correlation between them (r=0.32, y=0.25x+65) and the correlation did not improve when lesions with remodeling, enlargement (n=176) or shrinkage (n=79) were omitted from the calculation. The EIs by QCA and IVUS were 0.51+/-0.26 and 0.52+/-0.22, respectively (NS), and there was no correlation between them (r=0.30, y=0.36x+33). However, when the lesions with remodeling were excluded, the correlation greatly improved (r=0.80, y=0.84x+10.6, p<0.05). Lesion length determined by QCA (12.4+/-6.1 mm) was significantly shorter than that by IVUS (16.3+/-8.9 mm, p<0.01). These results demonstrate that coronary angiography significantly misinterprets disease morphology in terms of severity, eccentricity and length, in part because of vessel remodeling that can be accurately determined only by IVUS.