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Original Contribution
A Technique for Type 4a Coronary Bifurcation Lesions: Initial Results and 6-Month Clinical Evaluation
April 2003
Percutaneous coronary intervention (PCI) of bifurcation lesions remains technically challenging.1,2 Immediate and mid-term results using balloon angioplasty are not always satisfactory for various reasons, such as low angiographic success rate (in the range of 75–85%), high complication rate (8–22%) and high restenosis rate (40–65%).3–5 Furthermore, first-generation stents such as the Palmaz-Schatz and Cook stents were not proven satisfactory in this clinical setting, as the small sidebranches were sacrificed in some cases or dilated with difficulty in others.6–8 More recently, the development of low-profile balloons and new generation stents in combination with the thienopyridine-aspirin regimen have progressively modified our everyday practice in coronary angioplasty; therefore, coronary stenting has become a routine technique with highly predictable results in the majority of cases. In this report, we describe our initial experience with a new technique for the treatment of type 4a bifurcation lesions (main branch ostial lesion stenosis of the main vessel immediately after the bifurcation, not involving the sidebranch) (Figure 1) using a new technique for primary stenting of the main vessel with simultaneous kissing balloon of the sidebranch in an effort to avoid the snowplough effect.
METHODS
The method consists of the placement of two guidewires in both vessels (the main vessel and sidebranch). We then position a stent directly in the main vessel (with the stenosis) and a plain balloon in the sidebranch (without stenosis) (Figure 2). The stent is carefully positioned just after the origin of the sidebranch. Precise positioning of the stent is crucial. The plain balloon is positioned half in the sidebranch and half in the main vessel (this balloon is purposely mildly undersized). We then simultaneously inflate the stent (usually *with nominal pressure) and the balloon (usually with low pressure). If needed, we redilate the stent with higher pressure by slightly pulling the balloon, in order to avoid edge dissection, always with simultaneous inflation of the side balloon (Figure 3). By using this technique, we try to avoid plaque shifting toward the healthy branch, protecting stent geometry at the same time.
RESULTS
We used the above technique in the treatment of 11 patients (10 male, 1 female, age 52 ± 7 years). Six suffered from unstable angina and 5 from stable angina. Ten of the lesions were located in the left anterior descending artery (LAD)/diagonal (Dg) and 1 was located in the circumflex (Cx)/obtuse marginal (OM) bifurcation. We used 11 stents [five AVE stents (Medtronic), three Multi-Link Penta stents (Guidant Corporation, Temecula, California) and three Velocity BX Sonic stents (Cordis Corporation, Miami, Florida) with a mean diameter of 3.2 ± 0.2 mm and a mean length 16 ± 2 mm]. The immediate angiographic success was 100%. There was no plaque shifting toward the healthy branch or altered stent geometry in any patient. We did not observe any dissection, either proximal or distal to the stent. All patients followed the aspirin/clopidogrel protocol and there was no acute or subacute thrombosis. The patients were followed for 6 months, both clinically and non-invasively. All patients remained asymptomatic and the 6-month target lesion revascularization rate was negative. Three patients underwent plain exercise test and 7 patients underwent thallium scintigraphy at 6 months. The exercise tests and the nuclear scans were reported as negative for reversible ischemia. One patient had positive thallium scan (LAD/Dg bifurcation) and underwent coronary angiography, which showed no angiographic intrastent restenosis or sidebranch stenosis (Figure 4). The patients have been followed clinically since the procedures (mean follow-up period, 16 ± 6 months) and they remain asymptomatic.
DISCUSSION
In routine practice, lesions in coronary bifurcations are frequent. This relatively high frequency may be underestimated due to the presence of “false” bifurcation lesions (lesions of the main branch without significant lesion of the sidebranch), which may become true bifurcation lesions in the majority of cases after stenting due to axial plaque redistribution. Type 4a lesions are observed in less than 10% of cases. The initial approach to this type of bifurcation lesion was to carefully position the stent at the level of the lesion just distal to the bifurcation. In fact, due to the axial plaque redistribution phenomenon, there is frequent plaque shifting proximal to the stent, in the sidebranch, often leading to implantation of 1 or even 2 additional stents. Therefore, the current strategy is stenting of the main branch, covering the sidebranch and then correcting the snowplough effect to the sidebranch by kissing balloon inflation and provisional T-stenting of the sidebranch. However, by using the above technique, there is always the problem of difficulty (or even failure) crossing the struts of the parent stent, therefore compromising flow to the sidebranch. Our technique is simple and provides simultaneous protection of the sidebranch, which is free of disease, as well as the geometry of the stent in the main vessel. With the advent of lower-profile coronary stents, the possibility of direct stenting has become a reality. As a consequence, coronary stent implantation without balloon predilatation has many advantages over the standard technique, especially in unstable coronary syndromes where the plaque is usually soft. These advantages include reductions in case time, radiation exposure and procedural cost, as well as reductions of ischemic time and possibly embolic risk.9–11
The treatment of bifurcation disease is challenging and the result is unpredictable in some cases.12,13 The use of coronary stents, although technically more demanding, has led to improved angiographic and clinical results; however, there is an unpredictable risk of compromising the flow of the sidebranch.14–16 The combination of plaque shifting and altered stent geometry continues to limit even the most angiographically “perfect” results. From a practical standpoint, because of the limitations of current technology, the interventionist needs to simplify the approach and focus predominantly on the parent vessel with the sidebranch functioning as a bystander.17 By protecting the sidebranch, one can prevent plaque shifting toward the healthy branch and protect stent geometry at the same time. We believe that the new technique we describe is applicable in type 4a bifurcation lesions, simple to use (provided that the parent stent is positioned properly) and cost effective. Furthermore, the radiation exposure time is significantly reduced. However, we should wait for longer follow-up and more complete angiographic follow-up results.
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