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Treatment of Stent-Jailed Side Branch Stenoses with Rotational Atherectomy
August 2006
Percutaneous intervention of coronary ostial stenoses carries a lower procedural success rate and a higher likelihood of acute complication and need for repeat revascularization. Technical challenges related to the treatment of ostial side branches include smaller vessel size, an angulated orientation of the side branch relative to the parent vessel, vascular recoil and plaque shifting into the parent vessel in response to balloon angioplasty. Stents that have been placed in the parent vessel across the origin of side branches confer an additional level of complexity to percutaneous treatment of the side branch. The metal struts of the stent may impede guidewire or balloon access to the “jailed” side branch, and also may limit effective balloon expansion within the side branch. In addition, potential complications of balloon dilatation of side branches through stent struts include device entrapment as well as deformation of the stent struts in the parent vessel.
Rotational atherectomy is an effective method for debulking plaque, thereby reducing recoil and plaque shift at the origin of side branches. Several case reports from our institution and others have documented the safe and successful use of rotational atherectomy to treat stenoses at the origins of jailed side branches.1–6 We hypothesized that rotational atherectomy is a safe and effective approach to treating stent-jailed ostial side branch disease, with acceptable acute- and long-term outcomes. To investigate this hypothesis, we analyzed the in-hospital and intermediate-term outcomes in 30 consecutive, unselected patients who underwent 38 procedures, using rotational atherectomy to treat ostial lesions in stent-jailed side branches.
Methods
Between September 26, 1996 and August 23, 2001, a total of 30 consecutive, unselected patients who underwent rotational atherectomy for jailed side branch stenosis underwent 38 procedures, including rotational atherectomy to treat 32 distinct ostial lesions in stent-jailed side branches 39 times (1 patient had 2 distinct stent-jailed ostial lesions treated with rotational atherectomy during a single procedure; 1 patient had 2 distinct stent-jailed ostial lesions treated with rotational atherectomy during 2 separate procedures; 7 distinct lesions underwent repeat revascularization with rotational atherectomy). Rotational atherectomy was performed in the side branch and frequently in the parent vessel using a “stepped burr” approach over a rotational atherectomy guidewire (RotaWire™ Floppy or RotaWire™ Extra Support, Boston Scientific Corp., Natick, Massachusetts). Following debulking with rotational atherectomy, adjunctive balloon angioplasty was performed on all lesions. Frequent revascularization of the parent vessel was also performed with the use of the simultaneous balloon inflations in the parent and side branch vessels (i.e., “kissing balloon” technique) in the majority of cases. Intracoronary brachytherapy with radiation was used in 4 treatments (3 with beta and 1 with gamma radiation). Rotational atherectomy was not performed in the setting of acutely stent-jailed side branch stenosis.
Quantitative coronary analysis (QCA) was performed prior to and after intervention at the Perfuse Core Laboratory (Boston, Massachusetts) using a previously-described and validated automated edge detection algorithm,7 with the contrast-filled catheter as a reference. A selection was made of the single-plane projection that most clearly identified the stenosis in its greatest severity with minimal foreshortening or overlapping of branches. The interpolated diameters of the normal segment proximal and distal to the traced area of stenosis in the parent vessel was used to determine the parent reference diameter, and the diameter of the normal segment distal to the traced area of stenosis in the side branch was defined as the side branch reference diameter. Lesion length in the side branch was defined as the distance from the proximal edge of the lesion, which was always at the ostium, to the distal shoulder of the lesion. Angiographic success was analyzed on a per-lesion basis, and was defined as /= 3 times normal (30 ng/ml).
Intermediate clinical follow up was obtained via telephone interview and review of the medical record to ascertain each patient’s vital status and the need for repeat revascularization by percutaneous intervention or coronary artery bypass graft surgery. Intermediate follow up was analyzed on a per-lesion basis, except for death, which was analyzed on a per-patient basis. The decision to perform follow-up angiography was clinically driven. Restenosis was defined as >/= 50% stenosis at the site of the previously treated lesion more than 30 days following the index procedure.
Continuous data are presented as mean ± standard deviation unless otherwise indicated, and were compared using the unpaired Student’s t-test. The Kaplan-Meier method was performed on a per-lesion basis and was used to estimate freedom from any TLR for side branch and parent vessel lesions that had been initially treated with angiographic success. A p-value £ 0.05 was considered statistically significant.
Results
Patient and baseline lesion characteristics. Patient demographics are shown in Table 1. Of note, the majority of patients had multivessel disease, 18.4% had diabetes mellitus, and almost 20% had a history of prior coronary artery bypass graft surgery (Table 1). The majority of the treated side branches were diagonal branches (Table 2). More than 70% of stents in the parent vessel were slotted-tube designs. As is our standard practice when treating stent-jailed side branches with rotational atherectomy, the stent struts covering the side branch origin were dilated prior to the index procedure in over 85% of cases to facilitate burr passage and to reduce the risk of burr entrapment.
Procedural characteristics. An average of 1.53 ± 0.72 burrs were used to treat each side branch lesion, with a mean burr size of 1.62 ± 0.31 mm and a size range of 1.25 mm to 2.25 mm (Table 3). The mean maximum burr-to-artery ratio was 0.79 ± 0.12, using the nominal burr size and the maximum reference diameter of the side branch by QCA. Adjunctive PTCA was performed in all 39 lesions, with a mean maximum balloon pressure of 9.15 ± 3.05 atm (range 4 to 16 atm). The mean maximum balloon-to-artery ratio was 1.26 ± 0.18, using the nominal balloon size and the maximum reference diameter of the branch by QCA. Revascularization of the parent vessel, which required positioning the guidewire in the distal parent vessel, occurred in two-thirds of cases; this was usually due to a lesion in the parent limb just distal to the side branch origin. The kissing balloon technique was used in more than 50% of cases. Intracoronary brachytherapy was administered in 4 of 39 treatments (3 beta, 1 gamma).
Acute angiographic results and periprocedural outcomes. The mean reference vessel diameter of the side branch was 1.99 ± 0.36 mm, and did not change significantly following treatment with rotational atherectomy or PTCA (Figure 1A). The minimum luminal diameter (MLD) of the side branch increased significantly from 0.43 ± 0.25 mm to 1.21 ± 0.34 mm following rotational atherectomy (p Intermediate clinical follow up. Follow up was obtained for all patients after each procedure for a median of 664 days and a range of 1 to 1,700 days. Clinically-driven follow-up angiography was performed 19 times following 28 index procedures (19/28 = 67.9%) that achieved angiographic success in both the side branch and parent vessels. Angiographic restenosis occurred in either the side branch or the parent vessel in 13 cases (Table 5). Of the 29 side branches that initially underwent angiographically successful procedures, clinically-driven repeat revascularization was performed in 13 cases (13/29 = 44.8%). However, 2 of these cases had follow-up diameter stenoses of 27% and 33%, and at least 1 of these cases of mild restenosis underwent repeat revascularization after plaque shift into the side branch during treatment of significant parent vessel restenosis. Of the 32 index side branch lesions in which both the side branch and the parent vessel were successfully treated, clinically-driven repeat revascularization of either the side branch or the parent vessel was performed in 13 cases (13/28 = 46.4%). The estimated freedom from any TLR was 47.7% at 300 days (Figure 2). There was 1 death of unknown etiology which occurred 253 days following the index procedure.
Discussion
PTCA of stenoses at the origin of side branches generally has a lower procedural success rate and a higher incidence of complications compared with PTCA of non-ostial lesions.8,9 Rotational atherectomy, which relies on plaque abrasion and pulverization to reduce elastic recoil and plaque shifting, has been used with a high procedural success rate for aorto-ostial and branch-ostial stenoses.10–12 Coronary ostial side branch stenoses jailed by parent vessel stents represent a particular technical challenge for percutaneous revascularization. Although balloon angioplasty has been used to reopen jailed side branches, procedural success was achieved in only 84% of cases, with a mean residual diameter stenosis of 28 ± 6%.13 While several case reports have described the successful use of rotational atherectomy to treat stent-jailed ostial side branch stenoses, long-term clinical outcome is unknown.1–6
In this study we reviewed a consecutive, unselected series of 30 patients undergoing 38 procedures involving treatment of 32 stent-jailed ostial side branch lesions treated 39 times. Angiographic success was achieved in 92% of treated side branches, which compares favorably with previous studies of balloon angioplasty to treat ostial side branch stenoses, with reported angiographic success rates ranging from 74% to 87%.9,14 In addition, we found an acceptable rate of procedural complications, including a 2.6% rate of periprocedural myocardial infarction, 1 case of stent thrombosis of the parent vessel proximal to the side branch and no cases of emergent CABG surgery or death.
Despite the high procedural success rate, repeat revascularization was common in our study. The TVR rate of 44.8% undoubtedly reflects the unfavorable impact of variables such small vessel size, ostial location and high incidence of previous revascularization of the treated side branches. Also, of the 13 cases of side branch TVR, 2 had mild restenosis (27% and 33%), and at least 1 underwent repeat revascularization due to plaque shift during treatment of the parent vessel. These cases of “innocent bystander” repeat revascularization increase the overall rate of repeat revascularization than might be anticipated following revascularization of isolated jailed side branch restenosis without parent vessel involvement.
An important technical consideration when using rotational atherectomy to treat side branches covered by stents is the importance of ensuring that the side branch has been previously dilated through the side of the stent. This may facilitate passage of the burr and may reduce the potential complication of burr entrapment. Another potential concern is the liberation of metallic particles during rotablation of the stent strut. However, there were no cases of periprocedural myocardial infarction following angiographically successful revascularization of side branches with rotational atherectomy in our series, suggesting that rotational atherectomy through the sides of stents can be performed safely.
Study limitations. Limitations of our report include the retrospective design of the study. Also, the comparison of rotational atherectomy with other modalities of revascularization, including plain-old balloon angioplasty or bifurcation stenting for the treatment of stent-jailed ostial side branch stenosis is precluded by the lack of a randomized control design. Furthermore, these were highly selected, rather than random, cases based on angiographic appearance; not every patient who had a stent-jailed side branch stenosis underwent treatment with rotational atherectomy. Another limitation is that some patients who received rotational atherectomy underwent adjunctive treatment with brachytherapy. Although brachytherapy should not affect the acute result, brachytherapy could affect the long-term outcome. However, the total number of stent-jailed side branch stenoses that received adjunctive brachytherapy is a small percentage of the total number of treatments (10%).
Our study is the first reported series of cases using rotational atherectomy to treat stent-jailed ostial side branch disease. Although we found that acutely, rotational atherectomy is a safe and effective approach, these data do not support the notion that rotational atherectomy is a superior technique compared with balloon angioplasty to treat stent-jailed side branch stenoses. In addition, restenosis remains a formidable clinical problem due in part to the location and size of the target vessels. Further studies are required to determine the optimal modality of therapy and the potential roles of newer interventional technologies, such as brachytherapy and drug-eluting stents, in treating these challenging lesions.
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