A Novel Technique for Coronary Bifurcation Lesions: Cutting Balloons, Drug-Eluting Stents and the Kissing Technique

Bifurcation coronary lesions remain challenging for interventional cardiologists. Before coronary stents were widely used, the rate of success of percutaneous revascularization was low and the procedure was fraught with complications and restenosis.¹ Different stenting techniques were described to tackle the problems,^2–5 but stent restenosis remains an ongoing problem. Recent studies⁶ have suggested that stenting the parent vessel and performing balloon angioplasty of the side branch may give a better intermediate-term result than stenting both branches. Dardas et al.⁷ proposed a novel technique of tackling type 4a coronary bifurcation lesions (according to Lefevre classification³) by stenting the parent vessel with simultaneous kissing balloon technique of the side branch to avoid the snowplough effect. The six-month result appeared to be very favorable. In this report, we attempted to further apply the technique to different kinds of bifurcation lesions, including types Ia, Ib, IIa, IIIa and IIIb lesions.³ Additional devices with cutting balloons and drug-eluting stents were used with the aim of optimizing the results. Cutting balloons, with the mechanisms of scoring the vessel with the blades to allow better luminal gain prior to coronary stenting, may achieve a lower loss index and less dissection, and probably less plaque shift than that obtained with other interventional devices.⁸ They may be beneficial in attaining significantly more gain in luminal areas prior to the stenting procedure.⁹ Recent studies show that the use of cutting balloons before stenting further reduced restenosis rates by 33% [Restenosis Reduction by Cutting Balloon Evaluation III (REDUCE III) trial; TCT 2003]. Drug-eluting stents, in various clinical studies,^10,11 have consistently been shown to reduce restenosis rates and may play an important role in percutaneous intervention of coronary bifurcation lesions. The technique is summarized in the following paragraph. Technique 1. In a typical type 13 bifurcation coronary lesion, the parent vessel and the side branch are crossed with two 0.014-inch guidewires. Subsequent to that, balloon dilatation at a nominal pressure is achieved by cutting balloon in the parent vessel, using 1:1 sizing. Slightly undersized balloons may be employed to avoid dissection (if the parent vessel proximal to the bifurcation is a much larger vessel, a 1.1:1 sized balloon may be required). Next, another cutting balloon dilatation is performed on the side branch vessel, again using a 1:1-sized balloon, or a slightly undersized balloon. At this point, there is a risk of significant plaque shifting in the parent vessel that creates a type 4a bifurcation lesion. In other words, the type 1 lesion is converted to a type 4a lesion, with a significant stenosis involving the parent vessel just distal to the bifurcation. Using the technique described by Dardas et al.,⁷ the drug-eluting coronary stent is placed in the parent vessel just distal to the bifurcation, covering the lesion. A 1:1-sized monorail balloon (preferably a longer balloon) is simultaneously placed in the side branch, straddling the parent vessel. Simultaneous kissing technique with inflation of the coronary stent balloons and the side balloons is performed. Precise positioning of the stent balloon is important. The operator may use a “draw-back stent deployment” technique described by Schwartz et al.^{12 to ensure accurate positioning of the coronary stent. Basically, the side branch balloon is inflated first to slightly sub-nominal pressure, and then the coronary stent is withdrawn until it makes contact with the side balloon while maintaining the inflation pressure of the side balloon. The stent balloon is inflated to the nominal pressure. After initial deployment of the stent is completed, the coronary stent is redilated with a high-pressure balloon which is pulled back slightly to avoid outflow dissection, and the side balloons are simultaneously dilated. With this method, plaque shifting toward the healthy branch can be avoided, while at the same time protecting stent geometry. Case Report 1. A 54-year-old man with a history of hyper-triglyceridemia and a previous smoking habit was admitted to our hospital for progressive angina. A noninvasive stress echocardiogram showed lateral wall ischemia with an acceptable exercise tolerance result. A coronary arteriogram revealed an 80% stenosis of the mid-left anterior descending artery (LAD) associated with a diffuse bifurcation diagonal lesion 70–80% (type IIIa bifurcating lesion), involving the ostial, proximal and mid portion (Figure 1A). He was initially kept on medical treatment but developed progressive angina and shortness of breath despite optimal pharmacological therapy. Percutaneous intervention of the LAD and diagonal arteries was therefore performed. An 8 French JL 4 guiding catheter was successfully cannulated in the ostium of the left main coronary artery. A 0.014-inch ATW wire (Cordis, Warren, New Jersey) was steered into the left anterior descending artery and then crossed the obstruction without difficulty. Another 0.014-inch ATW wire was steered into the diagonal branch again without difficulty. A 2.5 mm x 10 mm cutting balloon (Interventional Technologies, San Diego, California) was used to dilate the LAD, followed by separate balloon dilatation in the diagonal branch using a 2.25 mm x 10 mm cutting balloon at a maximal pressure of up to 7 atmospheres. At that time, we observed significant plaque shift and recoil in the LAD. With the use of a 3.0 mm x 13 mm Cypher stent (Cordis) and a 2.5 mm x 20 mm monorail balloon, simultaneous deployment of the stent in the LAD and dilatation of the monorail balloon in the diagonal branch was done at nominal pressures (Figure 1B). Stent dilatation at high pressure was then performed, with the stent slightly pulled back; simultaneous balloon dilatation in the diagonal branch was also performed. The final result was excellent, with 0% residual stenosis in both branches (Figure 1C), and no evidence of plaque shift was seen. The patient received heparin and a glycoprotein IIb/IIIa inhibitor during the procedure. He was discharged home the following day on aspirin and clopidogrel. There was no evidence of clinical restenosis after a follow-up period of six months. Case Report 2. A 49-year-old man with a history of hypertension and a positive family history of coronary artery disease was admitted to our hospital secondary to intermittent left-sided chest pain and shortness of breath on moderate exertion. A stress cardiolyte test was performed and revealed inferior ischemia and a minimal anteroseptal defect was noted. The patient’s left ventricular systolic function was normal and the patient continued to experience significant angina on exertion. Diagnostic cardiac catheterization revealed luminal irregularities in the LAD and a 40% stenosis in the mid-circumflex artery. However, the right posterior descending artery had a 90% stenosis in the origin, associated with a 90% bifurcating lesion in the origin of the posterolateral branch (type IIIa bifurcation lesion; Figure 2A). The decision was made to proceed with ad hoc angioplasty and stenting. Using an 8 Fr JR 4 guiding catheter, the right coronary artery was successfully cannulated. A 0.014-inch ATW guidewire was subsequently used to cross the posterolateral branch without difficulty. A second 0.014-inch ATW wire crossed the posterior descending artery again without difficulty. A 2.75 mm x 10 mm cutting balloon was utilized to dilate the posterolateral branch at a pressure of up to 8 atmospheres. Another 2.75 mm x 10 mm cutting balloon was then used to dilate the posterior descending artery with a pressure of up to 8 atmospheres. At that time, it was apparent that there was significant recoil and plaque shift in the ostium of the posterolateral branch (Figure 2B). A 3.0 mm x 13 mm Cypher stent was deployed across the posterolateral branch. Simultaneously, a 3.0 mm x 15 mm monorail balloon was traversed across the posterior descending artery and the kissing technique was performed. Nominal pressures were used initially followed by high-pressure balloon dilatation of the stent. Finally, the kissing balloon technique at 6 atmospheres was applied to the posterolateral branch and the posterior descending artery of both branches, so as to preserve stent geometry (Figure 2C). The final result was excellent, with 0% residual stenosis in both branches (Figure 2D) and no evidence of plaque shift or dissection. The patient received heparin and a glycoprotein IIb/IIIa inhibitor during the procedure. He was discharged the following day and had no evidence of clinical restenosis at his six-month of follow-up. Also, the patient’s stress echocardiogram was negative four months after the interventional procedure. Discussion. Percutaneous intervention of bifurcation coronary lesions remains challenging. Different stenting techniques2–5 have been described, such as provisional stenting of the side branch with stenting of the main branch, “coulette” technique, crush technique, T stenting, Y stenting, V stenting and dedicated bifurcating stenting. Some of these techniques are technically demanding, such as those which involve crossing the stent struts with a third guidewire, or extensive overlapping of two metallic slotted-tube stents. The long-term results may also be unfavorable with most of the above techniques, especially those involving more than one stent. Dardas et al.7 described a technique for type 4a bifurcation lesions which is technically less demanding, and may confer a better long-term outcome since only one coronary stent needs to be used. We further modified their technique and applied it to some other forms of bifurcation lesions with the additional use of cutting balloons and drug-eluting stents. In order to enhance the chance of success of the technique, the following issues need to be addressed. First, in the proposed modified Dardas technique, the use of cutting balloons to dilate the main and side branch before stenting is employed. Plaque shifting is expected to occur with each balloon dilatation, even with cutting balloons. It is preferable to obtain an optimal result with the side branch dilatation without dissection and minimal residual stenosis. A slightly undersized cutting balloon with slow inflation and deflation may be able to achieve it. After the balloon dilatation of the side branch, plaque shifting to the main branch just distal to the bifurcation is expected to occur (thus a type 4a bifurcation lesion is created), which is of little concern since the final stenting procedure will relieve the stenosis. During the stenting procedure where the kissing balloon technique is employed, it is preferable to use a 1:1-sized compliant balloon on the side branch with slightly sub-nominal pressure, especially if the “draw-back stent” technique is used. If an undersized balloon is used in the side branch during the pull-back maneuver, the stent might be pulled back too much, causing the stent to be deployed too proximally. The practical problem with the “draw-back stent deployment technique” lies in the fact that contrast injection for guiding the positioning of the stent becomes impossible after the side branch balloon is inflated, making the final positioning of the stent a difficult task. Accurate positioning of the stent thus relies largely on a properly sized and properly inflated side branch balloon. There are certain limitations of the modified Dardas technique. The first generation cutting balloons currently available in the United States are typically high profile and may not be able to cross some of the tight lesions. Moreover, if the proximal part of the main vessel is much larger in size than the distal part beyond the bifurcation, the cutting balloon may not be able to optimally dilate the proximal portion, thus giving suboptimal results. On the other hand, if the proximal portion of the main vessel is of similar size to the distal portion, final kissing dilatation of both balloons while the stent balloons are pulled back may inflict trauma to the proximal portion of the main vessel, causing dissection. Therefore, low-pressure dilatation has to be maintained. Also, it is understandable that if dissection occurs in any portion of the vessel during cutting balloon or regular balloon dilatation, then multiple stents might be required for bail-out which might render a final suboptimal result. Therefore, using a slightly undersized cutting balloon and a meticulous technique in dilating and deflating the cutting balloons is important. Last but not least, the cost is an important issue in using this technique. Potentially, two cutting balloons, one regular long balloon and one drug-eluting stent have to be used in an uncomplicated bifurcation stenting procedure. The total cost amounts to approximately $5,000 to $6,000. It is thus an expensive procedure, but still less costly than using two drug-eluting stents, and less costly than coronary artery bypass surgery. Coronary artery bypass surgery using an off-pump technique is an attractive alternative, but may still carry a higher morbidity rate and a longer recovery period than percutaneous procedures. Patients’ preference is important in making the final decision in some settings. In summary, we described a novel technique modified from the one described by Dardas et al.7 to tackle bifurcation coronary lesions, which is technically simpler than most techniques described in the literature. Although our patients’ favorable outcomes cannot be generalized to other patients, and their long-term outcome is unknown at this time, we believe this new technique should have a role in tackling challenging bifurcation lesions in the future, especially with the use of cutting balloons prior to stenting (REDUCE III trial at TCT 2003), the use of one stent instead two,6 and the use of drug-eluting stents,10,11 which may further reduce restenosis rates. Further randomized trials are required to demonstrate the potential superiority of this technique.}

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