Clarissa Cola

Plaque vulnerability and related coronary event prediction by intravascular ultrasound with virtual histology: “It's a long way to tipperary”?

Identification of so‐called “vulnerable plaque” or “high‐risk” plaques have spawned manifold attempts to develop diagnostic tools capable to afford this task. This task is particularly challenging but the reward is high: local intervention on identified “vulnerable plaque” could preclude plaque thrombosis and possibly prevent acute coronary syndromes. Various imaging techniques are currently under investigation by extensive clinical testing to identify which could become the most sensible and specific modality for vulnerable plaque detection. Noninvasive techniques are fascinating for their easily applicability to a broad population but nowadays are not sufficiently powered for this task. The emerging technologies with the greatest resolution are indeed catheter‐based and many intravascular modalities have been developed for identification of “vulnerable plaque”. Among these, IVUS‐Virtual Histology™™ (IVUS‐VH) is the most promising technique in the field. IVUS‐VH offers an in vivo opportunity to assess plaque morphology and histology. IVUS‐VH uses underlying frequency information along with echoes intensity, while grey‐scale IVUS data are obtained from echoes of different intensity or amplitude. The major advantage of IVUS‐VH is that it is based on a device that is practical for use in the clinical setting and that it generates a real‐time assessment of plaque morphology. Unfortunately, numerous challenging issues still need to be overcome until the numerous “vulnerable plaques” could be identified and successfully treated. Future efforts may identify plaques that are on a trajectory of evolution toward a vulnerable state, and help us target interventions to those plaques most likely to develop plaque disruption and related complications.

Randomized Comparison Between Polymer-Free Versus Polymer-Based Paclitaxel-Eluting Stent Two-Year Final Clinical Results

Background—Most drug-eluting stents currently in use are coated with a polymer carrying the drug that is released for several weeks. However, a durable polymer may provoke hypersensitive reaction, delayed artery healing, and eventually stent thrombosis. The aim of this study was to investigate the safety and efficacy of a polymer-free paclitaxel-eluting stent (PF-PES) versus a polymer-based PES (PB-PES). Methods and Results—Eligible patients undergoing percutaneous coronary intervention were randomized 1:1 to receive either PF-PES or PB-PES. The primary end point was late loss at 9 months. Intravascular ultrasound analysis at 9 months and final 2-year clinical follow-up were also performed. From October 2007 to April 2009, 164 patients were enrolled and randomized into 2 groups (PF-PES: n=84; PB-PES: n=80). Mean in-stent lumen loss was 0.90±0.59 mm for PF-PES and 0.49±0.52 mm for PB-PES (P<0.001). Mean neointimal area by intravascular ultrasound was higher in PF-PES than in PB-PES (1.42±1.09 versus 0.51±0.61 mm2; P<0.001). At 2 years, a composite end point of all-cause death, any myocardial infarction, and target vessel revascularization occurred in 36.9% for PF-PES and 16.3% for PB-PES (P=0.004), mainly driven by a higher rate of target vessel revascularization (PF-PES: 35.7%; PB-PES: 13.8%; P=0.001). One late stent thrombosis was observed in PF-PES. Conclusions—Compared with PB-PES, PF-PES was associated with increased neointimal proliferation and subsequent clinical restenosis. Polymer plays an essential role in the performance of drug-eluting stents. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT01375855.

Vascular response at proximal and distal edges between polymer-free and polymer-based paclitaxel-eluting stents: intravascular ultrasound analysis

Aim: Polymer-based paclitaxel eluting stent (PB-PES) has shown to have a positive vascular remodeling at the distal edge compared to bare metal stent (BMS), probably due to higher downstream concentrations of the drug in comparison to proximal edge. The AXXION stent is a polymer-free paclitaxel eluting stent (PF-PES), whose dosage of drug is approximately 2.7 μg/cm2 compared to 1.0 μg/cm2 of the PB-PES. The purpose of this study was to compare vascular responses in adjacent segments between PF-PES and PB-PES. Methods and results: Consecutive 164 patients undergoing percutaneous coronary intervention were prospectively randomized 1:1 to receive either PF-PES or PB-PES (Clinicaltraials.gov [NCT01375855][1]). All patients provided written informed consent for their inclusion into IVUS examination at post-procedure and 9-month follow-up. Paired serial IVUS data were available in 76 patients with 84 lesions (38 patients with 41 lesions for PB-PES and 38 patients with 43 lesions for PF-PES). Baseline patient and lesion characteristics were similar between 2 groups. No significant differences were observed between PB-PES and PF-PES in terms of change in vessel area either at proximal (16.77±5.20% vs. 15.97±4.27%; p=0.450) or at distal segment (11.59±4.91% vs. 11.03±4.74%; p=0.546). No differences were also found in the percentage of change in plaque area (-5.73±42.81% for PB-PES vs. 9.81±32.91% for PF-PES; p=0.122) and in lumen area (0.43±19.42% for PB-PES vs. -5.70±17.87% for PF-PES; p=0.178) at proximal edge. Conversely at distal edge, a significant increase in plaque area was observed with PF-PES compared to PB-PES. (plaque area: 2.23±18.54% for PB-PES vs. 12.59±28.62% for PF-PES; p=0.038) with subsequent reduction in lumen area (5.82±21.18% for PB-PES vs. -4.98±17.59% for PF-PES; p=0.024). Conclusion: PF-PES did not seem to have a different edge response as compared to PB-PES. In particular they seem to increase plaque area with lumen reduction at the distal edge, probably due to differences in polymer-base drug release between the two platforms. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT01375855&atom=%2Fehj%2F34%2Fsuppl_1%2FP3945.atom