Extensive Right Coronary Artery Dissection <br />
Following Cutting Balloon Treatment of In-Stent Restenosis<br />

Case Description. A 44-year-old female was readmitted with chest pain on minimal exertion. She was an ex-smoker and had hypercholesterolemia. Eight months previously, she had experienced an episode of unstable angina and underwent coronary angiography, which demonstrated an essentially normal left coronary artery and a critical stenosis of the proximal right coronary artery. This was stented directly with a 3.5 x 15 mm NIR Royal stent (Boston Scientific/Scimed, Inc., Maple Grove, Minnesota). She was discharged on aspirin and clopidogrel for one month and was well until pain recurred three months later. There was no exertional component, but the pain was relieved rapidly by GTN. Repeat coronary angiography revealed that the left coronary appearances were unchanged, but there was some in-stent restenosis within the right coronary stent, although the severity was difficult to assess. There was also possible disease just distal to the end of the stent (Figure 1A). Patient management. In view of the slightly atypical nature of her symptoms, we decided to undertake intravascular ultrasound prior to repeat intervention. This confirmed significant in-stent restenosis (Figure 1B) (Atlantis SR Coronary Imaging Catheter; Boston Scientific/Scimed, Inc.). Balloon dilatation was undertaken using a Judkins right 5 guide and 0.014´´ BMW wire (Boston Scientific/Scimed, Inc.). A 3.75 mm cutting balloon was deployed at 8 atmospheres. This resulted in extensive dissection from the distal edge of the stent to the crux (Figure 1C). Balloon inflation was undertaken to try and decompress the dissection without improvement in antegrade flow. A coronary stent was placed over the origin of the dissection (3.5 x 22 mm, Biodivysio, Galway, United Kingdom). Antegrade flow remained poor and repeat intravascular ultrasound examination demonstrated persistence of a large occlusive dissection compressing the true lumen (Figure 1D). Further stenting was performed using 3 x 18 mm and 3 x 24 mm S670 stents (Medtronic AVE, Santa Clara, California) to cover the area of the dissection. Subsequently, a 3.5 x 20 mm Viva NC balloon was used to optimize the result (Figure 1E). ReoPro (Eli Lilly & Company, Indianapolis, Indiana) was administered, particularly as there was persistent dissection of the left ventricular wall branch. How Would You Manage This Case? Gregg W. Stone, MD Cardiology Research Foundation, New York, New York The patient in the present case unfortunately developed a severe dissection after cutting balloon angioplasty for in-stent restenosis, necessitating placement of multiple additional stents to manage acute vessel closure. The result was excellent. As the response to the complication was for the most part appropriate and successful, the discussion will focus on whether this was an avoidable complication. The patient presented with rest pain relieved by nitroglycerin, without an exertional component. Yet the angiogram reveals only modest in-stent restenosis. Was this lesion truly causing angina, and if not, could intervention (and the consequent complication) have been deferred? IVUS was performed, which is a useful diagnostic test for borderline lesions; a minimal cross-sectional area (CSA) Scott Goldman, MD Mainline Health System, Wynnewood, Pennsylvania Treatment of in-stent restenosis is probably one of the lower risk coronary interventions, due to the protection of the previously implanted stent. This case highlights the misadventure which can nonetheless ensue — a distal spiral dissection. The interventionalists likely thought this mild-to-moderate in-stent restenosis case would be a simple and straightforward angioplasty, or a “slam-dunk”. Instead, a nightmare ensued. To their credit, prior to embarking on the intervention, they further evaluated the lesion with IVUS. To my eye, the IVUS image provided appears to represent a lesion of borderline significance, although this is based upon the limitation of the single snapshot provided. The lumen area on this ultrasound picture appears to be right around 4 mm2, which is just at a cut-off correlating with recurrence of symptoms, abnormalities on nuclear stress testing, and intravascular physiological perturbations (The long length of the in-stent restenosis may have made even a moderate narrowing physiologically important, though). When an intravascular evaluation is equivocal, as this one appears to be, it is sometimes useful to evaluate with another test for confirmation, such as a pressure wire determination of FFR, or a nuclear stress test. If either of these studies were normal, the intervention may be deferred, with a low risk for further intervention. This case goes a long way towards justifying the extra cost and time involved in such careful evaluation for selected cases. If a FFR of > 0.75 was found, the angioplasty could have been avoided, in which case this significant complication would not have occurred. I am certain, after the excitement that ensued, that in retrospect they wished they had found a reason not to have performed this apparently straightforward angioplasty, and a FFR may have provided them with such a reason, given an equivocal IVUS. The cutting balloon appears to be very effective in the management of in-stent restenosis, based upon observational studies. The cutting balloon appears to displace more of the intra-stent neo-luminal tissue than plain balloon angioplasty. It is tempting to second-guess the sizing of the cutting balloon. Again, based upon the single image of the IVUS study, the stented vessel appears to be about 3.5 mm. It is unclear if the selection of a 3.75 mm cutting balloon was based upon the IVUS measurements, or based upon the intent of oversizing the angiogram. Several studies have suggested the balloon sizing based upon a media-to-media measurement performed on the IVUS imaging is safe and effective. This will frequently appear oversized based upon the angiogram. It is recommended to oversize the cutting balloon by a quarter size, but this is based upon the angiogram, not on the IVUS. Did the operators oversize based upon the IVUS, that is, go beyond the media-to-media diameter? If so, this could lead to a dissection, or even rupture, of an unprotected, unstented segment. This will usually occur distal to the stent, where the vessel is often smaller. Monday morning quarterbacking aside, it is possible the spiral dissection may have occurred independent of the operator’s technique. Each coronary artery may have its own peculiar tendency towards complications. The circumflex has proximal angulation with which to contend, and the LAD tapers more than the other vessels. The RCA appears to be more dynamic than the left, with greater movement in the cardiac cycle, as well as more rotational torsion. Could greater rotational torsion predispose RCAs to spiral dissections? Also, there may be characteristics of the lesion, the balloon and the vessel predisposing to this type of a complication. A rigid bit of plaque abutting normal vessel may provide a starting point for an extensive tearing within the media. Perhaps there was some inflammation at the edge of the restenotic process affecting the vessel wall. Finally, it is intriguing to note that this was a relatively young woman, leading to speculation on the effects of the perimenopausal hormonal state on coronary artery fragility. The operators were able to stent the distal vessel, eventually obtaining a good angiographic result. After the placement of the first stent to seal the the dissection, the flow remained poor. IVUS was done, which was quite interesting and relevant. They did not find intravascular thrombus, or an intravascular hematoma, either of which could cause slow flow in this setting and would be managed quite differently, with either greater or lesser amounts of anticoagulation. Instead, they were able to visualize the severe dissection, and possibly identify its extent. By sealing the length of the dissection, the flow normalized. Patrick Whitlow, MD Cleveland Clinic Foundation, Cleveland, Ohio Diffuse in-stent restenosis, especially the type that extends beyond the stent border, remains a significant problem for PCI. Our primary approach to this aggressive proliferative response is to first IVUS the stent to identify true reference vessel size and to make sure that the stent is adequately deployed. If the stent was really small for the artery IVUS reference diameter, then I typically use rotablation to remove a significant amount of in-stent restenotic volume followed by high-pressure balloon dilation to further expand the stent. However, if intimal proliferation is the major problem, as in this case, then I typically treat the lesion with cutting balloon angioplasty followed by brachytherapy. With the cutting balloon, it is important to inflate the balloon very slowly to let the microtome blades extend outward from the balloon without disrupting the arterial wall. I generally inflate the balloon up to 8 ATMs over 1 minute and leave the balloon inflated for 3 minutes. This usually yields good results, although we occasionally see a dissection, as occurred in this case. When a dissection occurs after cutting balloon angioplasty, further attempts at balloon angioplasty have rarely been successful in resolving the problem. Just as in this case, stenting of the entry into the dissection is usually necessary to seal the flap. After sealing the entry point into the dissection with the first stent, I’d probably have placed a 38 mm stent from the crux chordis backwards into the distal right coronary, hoping to seal the major exit point of the dissection. Then a shorter stent could be placed between the proximal and distal stents if needed. Often the dissection is completely sealed by concentrating on the entry and exit points. Although abciximab has not been proven to be of benefit when used as a bailout strategy for complications of PCI, I believe that it does indeed help to minimize the risk of abrupt closure when a flap is left uncovered. The AV branch of the RCA is a small vessel, and stenting would almost surely end in malignant restenosis. I believe that leaving that distal dissection in a small branch and adding abciximab is a wise compromise for this patient. Barry George, MD Riverside Methodist Hospital, Columbus, Ohio This case is interesting to “armchair quarterback” for several reasons. I will try to expand on each of the issues I see relevant to this case. First of all, the question of whether or not to reintervene or perform physiologic testing is somewhat relevant. If this patient gave a history of characteristic chest pain precisely like that of her prestenting pain, I would not hesistate to reintervene, most particularly, if the previous intervention had resulted in prompt and dramatic relief. If that history was not present, stress Cardiolite examination as a prelude to coronary angiography is warranted for her “proof of purchase” coupon. If negative, I would treat initially for GERD and reevaluate. Secondly, presuming coronary angiography is performed and in-stent stenosis is identified, why was cutting balloon angioplasty (CBA) alone done? We have developed extensive experience with cutting balloon angioplasty combined with brachytherapy for in-stent stenosis. The outcomes are very pleasing in regards to MACE. Without brachytherapy, I believe restenosis rates are unacceptable in 2001. On rare occasions, with very discrete in-stent stenosis, we may use CBA alone, but that is very unusual. Never have I seen an extensive spiral dissection from a cutting balloon within a stent. I believe this can only happen if the CBA was done outside the stent. In that scenario, a 44-year-old female RCA is a “sitting duck” for a spiral, propagating dissection. Once it happens, the distal dye stain (propagated dissection) must be stented first, then back stent. There is no other easy way out at that point. Next, I would reserve “a table for two” at 3–4 months for anticipated restenosis and ad hoc brachytherapy, since a large amount of metal had to be used. Certainly, close clinical follow-up of this patient, now at even greater risk of in-stent stenosis, is warranted. One final practical note regarding CBA I believe is worth mentioning. A general axiom we have adopted is this: This of the merits of using CBA in situations where stents have “burned you”. Isn’t it fun to second-guess when you’re not in the hot seat?