"Black hole": echolucent restenotic tissue after brachytherapy

The Best Strategy for the Black Hole Phenomenon between Intravascular Ultrasound and Optical Coherence Tomography

The black hole (BH) phenomenon is an intraluminal restenotic lesion. It was identified by intravascular ultrasound (IVUS) and optical coherence tomography (OCT) after intracoronary brachytherapy and drug-eluting stent implantation. Despite the similarity in the mode of action of brachytherapy and drug-eluting stent implantation, the BH phenomenon appears to be uncommon after drug-eluting stent implantation. Specifically, the BH phenomenon is better identified by OCT than by IVUS. Herein, we present a case of in-stent restenosis with suspected BH phenomenon on IVUS and confirmed by OCT.

Time course of restenosis with "black hole" on intravascular ultrasound after implantation of platinum-chromium everolimus-eluting stent: Assessment using optical frequency-domain imaging

Management of in-stent restenosis (ISR) remains challenging even in the drug-eluting stent era. We report the case of a Japanese female with repeated ISR after primary percutaneous coronary intervention (PCI) for acute coronary syndrome. We observed ISR tissue with "black hole" on intravascular ultrasound, which appeared to be heterogeneous tissue on optical frequency-domain imaging (OFDI). Paclitaxel-coated balloon dilatation of the ISR lesion with "black hole" was ineffective. The morphological assessment of ISR tissue using OFDI might be important to treat ISR lesions by PCI. OFDI is a novel tool to observe the difference in the in-stent tissue characteristics. <Learning objective: In-stent restenosis (ISR) remains a clinical problem even in the drug-eluting stent (DES) era. The morphological assessment of ISR tissue using optical frequency-domain imaging (i.e. homogeneous, heterogeneous, and layered types) might be important to treat ISR lesions by percutaneous coronary intervention since the reaction to DES and drug-coating balloon seems to be different according to the in-stent tissue characteristics.>.

Single-center randomized evaluation of paclitaxel-eluting versus conventional stent in acute myocardial infarction (SELECTION)

OBJECTIVES

To evaluate the superiority of the paclitaxel-eluting stent (PES) in reducing neointimal hyperplasia (NIH) over its corresponding bare metal stent (BMS) during primary percutaneous coronary intervention (PCI).

BACKGROUND

Primary PCI with stent implantation is the repercussion strategy of choice for ST-elevation myocardial infarction (STEMI); nonetheless restenosis rate is still high. Drug-eluting stents have been proven to reduce restenosis rate in many settings, but their use during primary PCI is still controversial.

METHODS

Consecutive patients with STEMI <12 hours were randomized to receive PES or BMS. The primary end-point was the percentage of the stent volume obstructed by neointimal proliferation (NIH) measured by intravascular ultrasound (IVUS) at a 7-month angiographic follow-up. Secondary end-points were binary restenosis rate and major adverse cardiac events (MACE, i.e., death, nonfatal myocardial infarction, and target lesion revascularization).

RESULTS

Eighty patients with STEMI were randomized into the PES or BMS group. Patients were well matched for baseline characteristics and the index procedure was always successful. In-hospital and 1-month MACE were 2.5% per group. NIH at 7 months was 4.6% versus 20% (P< 0.01), late lumen loss 0.1 versus 1.01 mm (P = 0.01). MACE were 7.5% versus 42.5% (P = 0.001) with no difference in death and recurrent myocardial infarction rates. Late-acquired incomplete stent apposition (ISA) rate was 5.1% versus 2.7% (P = 0.65). One subacute stent thrombosis was reported in each group.

CONCLUSIONS

PES was superior to its corresponding BMS in reducing NIH in the STEMI setting without any increase in early and long-term clinical adverse events.

Intravascular ultrasound characterization of the "black hole" phenomenon after drug-eluting stent implantation

An intraluminal echolucent tissue, dubbed "black hole," has been identified by intravascular ultrasonography after intracoronary brachytherapy. This study reports the characteristics and incidence of the black hole in patients treated with drug-eluting stent implantation using a sirolimus-eluting stent (SES). We included intravascular ultrasound data from the Compassionate Use of Sirolimus-Eluting Stent (SECURE, n = 61 lesions) registry, a study involving patients in whom previous brachytherapy had failed, and the DIABETES trial (n = 165 lesions), a multicenter, randomized study comparing SES versus bare metal stents in diabetic patients. Intravascular ultrasound follow-up was scheduled at 8 months (SECURE trial, post-brachytherapy population) and 9 months (DIABETES trial). In the SECURE population, a black hole was observed in 10 patients (19.6%). Seven black hole segments had significant intimal hyperplasia (> 10%). A black hole accounted for 27% of total intraluminal tissue. In the DIABETES trial, 2 patients (2.5%) in the SES group and none in the bare metal stent group showed echolucent intimal hyperplasia. In conclusion, a black hole occurred frequently after implantation of a SES in patients in whom intracoronary brachytherapy had previously failed. Black holes were also identified in a nonirradiated population, although the incidence was lower than in the post-brachytherapy patients. Bare metal stents were not associated with this phenomenon.

Evidence for "lumen sealing" with sirolimus eluting stents in the treatment of complex coronary artery dissection

Immediate and two month angiographic and intravascular ultrasound examination of sirolimus eluting stents deployed for complex coronary dissection is presented. The findings support the hypothesis that this novel treatment option is both effective and safe.

Late neointimal tissue growth behind the stent after intravascular γ-radiation

PURPOSE

To determine the nature of the changes of the vascular wall after intravascular brachytherapy in stented arteries leading to incomplete stent apposition.

METHODS AND MATERIALS

Stents were implanted in the infrarenal aortas of rabbits, and gamma-intravascular brachytherapy (18 Gy) or a sham radiation procedure was immediately implemented. The arteries were harvested at 6 months for histologic analyses.

RESULTS

The external elastic lamina area, as well as the vascular wall area behind the stent, were significantly greater in irradiated vs. control arteries (8.94 +/- 0.68 mm2 vs. 6.87 +/- 0.40 mm2 [p <0.001] and 1.56 +/- 0.13 mm2 vs. 0.72 +/- 0.07 mm2 [p <0.001], respectively). The ratio of the intimal area behind the stent related to the total intimal area was greater in the irradiated segments (control vs. irradiated: 9.0% +/- 5.9% vs. 55.3% +/- 15.5%, p <0.05). Neointimal growth of the irradiated vessels outside the stent was characterized by marked fibrin depositions and an inflammatory response around the stent struts.

CONCLUSION

Our study revealed the presence of a neointimal layer specifically located behind the stent, which represented the result of an unhealed fibrin-rich tissue growth process 6 months after intravascular brachytherapy.

Histopathology of coronary in-stent restenosis following gamma brachytherapy

The histopathology of in-stent restenosis (ISR) following gamma brachytherapy is described. Such histology has not been reported previously. An 82 year old man presented with recurrent ISR three months after gamma brachytherapy to an area of ISR within a native circumflex vessel. The recurrent ISR was treated with directional coronary atherectomy; the histopathology of this directional coronary atherectomy specimen is discussed. These histopathological examinations showed abundant extracellular matrix material. Surprisingly, there was a relatively small cellular (myofibroblastic) component, with an absence of endothelial cells and little evidence of active proliferation. ISR after gamma brachytherapy may be a pathologically distinct entity.

Coronary in-stent restenosis: current status and future strategies

In-stent restenosis (ISR) is a novel pathobiologic process, histologically distinct from restenosis after balloon angioplasty and comprised largely of neointima formation. As percutaneous coronary intervention increasingly involves the use of stents, ISR is also becoming correspondingly more frequent. In this review, we examine the available studies of the histology and pathogenesis of ISR, with particular reference to porcine and other animal models. An overview of mechanical treatments is then provided, which includes PTCA, directional coronary atherectomy and high speed rotational atherectomy. Radiation-based therapies are discussed, including a summary of current problems associated with this modality of treatment. Finally, novel strategies for the prevention of ISR are addressed, including novel developments in stents and stent coatings, conventional drugs, nucleic acid-based drugs and gene transfer. Until recently, limited pharmacologic and mechanical treatment options have been available for both treatment and prevention of ISR. However, recent advances in gene modification and gene transfer therapies and, more particularly, in local stent-based drug delivery systems make it conceivable that the incidence of ISR will now be seriously challenged.