Case Report. A 64-year-old Japanese male with hypertension and angina pectoris underwent minimally invasive coronary artery bypass grafting (MIDCAB) for the ostial left main trunk coronary artery (LMT) in 1998. In January 2001, the left internal thoracic artery (LITA) was occluded after percutaneous coronary intervention (PCI) for stenoses at the ostium of the LITA and at the anastomosis site with the LAD. A 3.5 mm x 9 mm NIRÆ stent (Boston Scientific Corporation, Natick, Massachusetts) was implanted at the ostial LMT. Repeat PCI was performed to treat distal edge restenosis of the stent in August 2001. The procedure was unsuccessful due to failure of the guiding catheter to engage.

Figure 1

Coronary angiograms before percutaneous coronary intervention. A) Antero-posterior view; B) left anterior oblique cranial view.

       The patient declined coronary artery bypass grafting (CABG) due to an unpleasant experience after a

Figure 2

Rotational atherectomy for stent struts. A) A 1.5 mm balloon catheter passed the stent strut, thus, the Transit microcatheter was inserted to exchange the guidewire for the RotaWireô; B) rotational atherectomy with a 2.15 mm burr; C) coronary angiogram after rotational atherectomy.

previous MIDCAB and came to our center for PCI. Thus, we decided to perform PCI after informed consent was obtained concerning the risk of PCI, including embolism to the brain or in the distal coronary artery caused by rotational ablation of the stent struts. The patientís left ventricular function was normal. Right coronary angiograms showed no significant stenosis. Left coronary angiograms demonstrated significant stenosis at the distal edge of the stent (Figure 1 A,B). Coaxial engagement of the guiding catheter was difficult, as the deformed and protruding stent struts at the ostium got in the way of the guiding catheter. We managed to cross the lesion with an ACS Hi-Torque Balance guidewire (Guidant Corporation, Indianapolis, Indiana) even though the wire may have entered the stent through the wall of the stent, and not through the major lumen of the stents. At this stage, we planned to use rotational atherectomy to get the stent struts out of the way. A Transitô microcatheter (Cordis Europe, Postbus, AD, Amersfoort) would not pass through the lesion. After balloon dilatation with the 1.5 mm MaverickÆ (Boston Scientific Corporation) (Figure 2A), the guidewire was exchanged with a RotaWireô (Boston Scientific Corporation) using a Transitmicrocatheter (Cordis Europe). Rotational atherectomy was

Figure 3

IVUS images after rotational atherectomy for stent struts. The white bar indicates the previously implanted NIR stent.

performed on the stent struts with sequential 1.75 mm and 2.15 mm burrs (Figure 2 B,C). Ablation was performed at 140,000 to 160,000 rpm through the stent struts into the LMT and the LAD, with a less than 1,000 rpm drop from the platform speed. The motion during ablation, which resembled a rapid pecking motion, was very careful and rapid. The burr was never pushed while crossing the struts. Intravascular ultrasound (IVUS) (Figure 3) revealed that the broken stent struts were separated from the ostium. The vessel size of the LMT was as small as 3.0 mm and diffuse intimal hyperplasia was detected in the stent and distal LMT. Following Cutting BalloonÆ (Interventional Technologies, Inc., San Diego, California) angioplasty (Figure 4A), a Tristar (Guidant Corporation) 3.0 mm x 23 mm stent was implanted from the LMT to the proximal LAD, entirely covering the previously implanted NIR stent, followed by the kissing balloon technique (Figure 4 B,C). IVUS showed that the stent was well dilated (Figure 5). The patient has remained asymptomatic and has had no CPK release or new ECG changes. He was angina-free 14 months after the procedures (Figure 6 A), with no angiographic restenosis (Figure 6 B, C).

Figure 4

Stenting followed by postdilatation with the kissing balloon technique. A) Dilatation with 3.5 mm x 10 mm cutting balloon at 8 atms after rotational atherectomy; B) kissing balloon technique after Tristar 3.0 mm x 23 mm deployment using a 3.0 mm stent balloon for the LAD and a 2.5 mm x 20 mm Maestro balloon (Jomed GmbH, Rangendingen, The Netherlands) for the LCX at 18 atm; C) final coronary angiogram in the right anterior oblique caudal view. LAD = left anterior descending coronary artery; LCX = left circumflex coronary artery.

       Discussion. To the best of our knowledge, this is the first case of PCI to treat protruding and deformed stent struts at the ostial LMT which interfered with the guiding catheter, much like ìstent jailî. Based on our previous experience,¹ we ablated the stent strut very carefully, and observed no complications. Neither slow flow nor distal embolization occurred. In this article, we discuss important issues that should be addressed for rotational atherectomy on stent struts.
       PCI has been recognized as a less invasive strategy for some LMT lesions, with acceptable short and late results.^2ñ5 A stent can be used for these lesions, with or without debulking. However, late results depend on the final lumen area at the MLD site.² The initial LMT stenting procedure our patient underwent at the previous hospital may have rendered him an unsuitable candidate in terms of late results because his LMT was small, thus significantly raising the risk for restenosis. That is, distal edge restenosis may have occurred in our patient due to the small size of his LMT. Stenting for LMT lesions sometimes causes a ìstent jailî when it crosses the branch (LCX or LAD). Furthermore, ablation with the

Figure 5

IVUS images after stenting followed by the kissing balloon technique. The short white bar indicates a previously implanted NIR stent and the long white bar shows a 3.0 mm x 23 mm Tristar stent.

RotablatorÆ device (Boston Scientific Corporation) becomes necessary for a compromised side branch because of a ìtrue stent jailî.^1,6 In this case, a deformed and protruding stent at the ostial LMT, resembling ìstent jailî, was the most challenging barrier during PCI. As a first strategy for this PCI procedure, rotational atherectomy was the only method considered to get the protruding stent struts out of the way.
       Previous reports have preferred a rotational speed between 160,000 to 170,000 rpm, in which rotational atherectomy to treat the ìstent jailî was often performed for a jailed diagonal artery by a stent in the proximal LAD.^6ñ9 Duvvuri et al.⁷ reduced the speed by less than 5,000 rpm. In this case, and in our previous reports, the rotational speed was usually set at between 140,000 and 180,000 rpm, with the speed reduced by less than 2,000 rpm. The hand motion during ablation was very careful and rapid, with the burr never pushed while crossing the struts. This is because experimental reports have indicated small metal particles can be projected distally after rotational atherectomy for stent struts.^10,11 In previous reports, the initial burr size was 1.25 to 1.50 mm, and increased up to 1.5 to 1.75 mm. Previous dilatation with balloon angioplasty before rotational atherectomy may decrease the metal injury caused by a burr crossing.² Balloon predilatation will enable any obstructive strut to be displaced laterally to treat the atherosclerotic lesion at the ostium. In the present case, predilatation with a balloon was performed using only a 1.5 mm balloon to pass the Transit without the use of a larger balloon. Because the stent strut seemed to be partially crushed or deformed and the Nir stent¹² provides poor side branch access, with less than 1.7 mm of maximal stent strut diameter after dilatation, using a larger-sized balloon was not considered an effective option to dilate the stent strut. Although we cannot differentiate between strut ablation from simple strut displacement with angiography or IVUS images, it would be impossible to displace the Nir stent struts with a 2.15 mm burr using only a pecking motion.

Figure 6

Follow-up coronary angiograms. A) 8 months after PCI, Cutting balloon angioplasty was performed to treat this diffuse in-stent restenosis; B) and C) coronary angiograms taken 18 months after the final PCI (high-pressure balloon dilatation with kissing balloon technique) in the right anterior oblique caudal view (B), and the left anterior oblique caudal view (C). There is no restenosis. PCI = percutaneous coronary intervention.

       Caputo et al.¹³ reported the results of plain old balloon angioplasty (POBA) for side branch stenosis with stent jail. Initial success was obtained in 84% of 45 cases. However, the initial results were often inadequate and the restenosis rates were high. Coronary dissection or balloon catheter trap in the stent may also occur. A report from Japan¹⁴ showed that directional coronary atherectomy was used to ablate stent struts, and may be a limited option in selected cases. These techniques may also require a more experienced operator.
       The potential concern regarding rotational atherectomy to treat ìstent jailî involves burr entrapment in the side branch if a relatively large initial burr size is selected. The larger burr may dotter its way into the side branch without actually ablating the tissue at the ostium. For this reason, a stepped burr approach was undertaken in our case to avoid any inadvertent jumping of the burr. Another theoretical concern is that of metal debris embolization into the distal bed of the artery, as well as heat generation from potential frictional interaction between the stent struts and the metal burr.¹⁵ Balloon rupture during postballoon dilatation after stent strut rotational atherectomy was described in a case report.⁶ In our previous three cases as well as the present case, we experienced no balloon rupture, even in a case in which a high-pressure kissing balloon technique was used. However, this technique requires very careful hand control during stent strut ablation because the edges of ablated struts may appear coarse¹⁰ in some cases. Previous reports^6ñ9 have demonstrated no angiographic restenosis or cardiac events in the late stage.
       Despite the favorable acute results achieved in the present case, there are still a couple of reasons to opt for another CABG surgery instead. First, this PCI was not cost-effective compared to CABG, as several PCI procedures and many devices were necessary. Second, although a second CABG also poses the potential risk of complications,^16,17 the degree might have been less, owing to the the fact that the patient had previously undergone a less invasive surgical strategy (MIDCAB).

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