Trifurcating Coronary Artery Disease: A Proposed Classification and Treatment Methodology

Trifurcating coronary artery disease is a complex atherosclerotic process involving the origin of one or more of three side branches (SB) arising from a main coronary artery vessel or trunk (MT), with or without involvement of the MT itself. Percutaneous treatment of this disease is often challenging and time-consuming, even with the most experienced operators. With the emergence of drug-eluting stents, interventional cardiologists have become more aggressive in treating complex coronary artery disease including unprotected left main disease in trifurcating vessels.¹ Small case reports have been reported or presented at national meetings with apparently good outcomes.^2–5 In contrast to bifurcation disease, trifurcation disease has not been classified and its treatment methodology has not been standardized. Classification of this disease and its methods of percutaneous treatment are particularly important in order to standardize our interventional approach and follow outcomes of treated patients. In this report, we propose a new, simplified classification for trifurcating coronary artery disease and describe various methodologies to treat the different types. In Part II of this report, we will report on our experience with percutaneous treatment of trifurcation disease using this classification methodology and drug-eluting stents. Disease Classification A trifurcating vessel consists of a main trunk (MT) and three branches: side branch 1 (SB1), middle branch (MB), and side branch 2 (SB2) (Figure 1). We propose a method of classifying the disease process based on whether the MT is involved (Type A) or not (Type B), and indicate subtypes within each type that address branch involvement. The classification is based on the fact that involvement of the MT adds a higher level of complexity to the disease process and requires a different treatment strategy. The following subtypes emerge for Type A lesions (Figure 1A): 1. Subtype A1: involving the MT with any single-branch disease (SB1, SB2 or MB) 2. Subtype A2a: involving the MT with any two adjacent branches (SB1 + MB or SB2 + MB) 3. Subtype A2b: involving the MT with opposing branches (SB1 + SB2) 4. Subtype A3: involving the MT and all three branches The following subtypes emerge for Type B lesions (Figure 1B): 1. Subtype B1: any single-branch involvement (SB1, SB2 or MB) 2. Subtype B2a: any involvement of two adjacent branches (SB1 + MB or SB2 + MB) 3. Subtype B2b: opposing branches involvement (SB1 + SB2) 4. Subtype B3: involvement of all three branches (SB1 + SB2 + SB3) Treatment Classification Figures 2 through 7 illustrate the different methodologies and final angiographic outcomes following percutaneous treatment of trifurcation disease. These methodologies are based on a combination of various bifurcating stenting techniques including the V-stenting, crush-stenting, T-stenting and Culotte techniques, with a proposed new nomenclature for trifurcation stenting. Figure 2 illustrates VT-stenting (V-T-stenting) for trifurcation disease utilizing a 9 Fr guide. The three branches are wired. Kissing balloon (KB) dilatation is performed as needed. Stents are first positioned into SB1, MB and SB2. The SB1 stent extends into the MT to cover the diseased area. The MB and SB2 stents are positioned to cover the ostium of these vessels in the V-stenting position. V-stenting on SB2 and MB is performed first. Wires and balloons are removed from SB2 and MB, and the SB1 stent is then deployed spanning over the ostium of SB2 and MB and into the MT. SB2 and MB stents are then rewired and KB dilatation is performed across the struts at high pressure (18–20 atm) with two balloons inflated simultaneously (SB1 and MB, SB2 and MB). Low-pressure (10–12 atm) triple-KB is then performed on all stents, assuming the MT size allows for it. This method is suited to treat lesions in the Type A category. Figure 3 illustrates CT-stenting (crush/T-stenting) for trifurcation disease utilizing a 9 Fr guide. The three branches are wired. KB dilatation is done as needed. The CT technique is carried out for MB to SB1. This is done with MB and SB1 stents positioned in a kissing position into the main trunk to cover the diseased area in the MT. The two stents are then deployed simultaneously. Following this, the SB1 balloon and wire are removed. The MB stent is then inflated to crush the SB1 stent against the MT. Following this, SB1 and SB2 are rewired and high-pressure KB is performed in the MB and SB1, and then the MB and SB2. SB2 is then stented using the T-stenting technique. High-pressure KB (18–20 atm) with two balloons inflated simultaneously in SB1 and MB and SB2 and MB is recommended. Low-pressure triple KB (10–12 atm) is then performed on all stents. This method is suited to treat lesions in the Type A category. Figure 4 illustrates the YV2 technique (Culotte-V/V-stent) for trifurcation disease. A 9 Fr guide is utilized. The three branches are wired. Kissing balloon (KB) dilatation is done as needed. The MT is first stented as close to the trifurcation as possible without jeopardizing the side branches and with the wire placed in the largest branch. Following this, the two remaining branches are rewired and KB is performed in the three branches. V-stenting is then performed in SB1 and MB, with an uninflated stent positioned in SB2. This is followed by KB in the MB and stent inflation in SB2. Following this, the three branches are dilated simultaneously with the kissing balloon at a low pressure of 10 atm. This technique is best suited for Type A lesions. A modification of this technique is the YV (Culotte-V-stent), where only SB1 and MB are stented, and SB2 is treated with balloon alone. Figure 5 illustrates TB-stenting for trifurcation disease. This involves T-stenting in SB1 and MB, treating SB2 with angioplasty alone. A 9 Fr guide is utilized. The three branches are wired. The MB is stented first with the SB1 stent positioned from the side branch into the main trunk. After deploying the MB stent, the stent balloon is removed and the SB1 stent is deployed. Then MB and SB2 are rewired and KB dilatation is performed at high pressure (18–20 atm), with two balloons inflated at one time in SB1 and MB, and low pressure (10 atm) in SB2 and MB to avoid dissection of the SB2 branch. Triple-KB at low pressure (10–12 atm) is then performed on all branches. This method is suited to treat lesions in the Type A category, primarily A1 and A2a lesions. Figure 6 illustrates VB-stenting for trifurcation disease utilizing a 9 Fr guide. After wiring the three branches, KB dilatation is performed as needed. The MB and SB1 (or SB2) are stented using the V-stent technique. KB is then performed on all three branches as needed. This method is suited to treat lesions in the Type B category, primarily B1 and B2a. Figure 7 illustrates V2-stenting for trifurcation disease using a 9 Fr guide. After wiring the three branches, KB dilatation is performed as needed. Stents are then positioned to cover the origin of all branches. The MB and SB1 are then stented first using the V-stenting technique. Then the balloon in the MB and the stent in SB2 are deployed using the stent/balloon kissing technique. KB is then performed on all three branches simultaneously using low-pressure inflation (10 atm). This technique is best suited for Type B3, B2a and B2b lesions. In conclusion, we propose a new classification for various phenotypes of trifurcation coronary artery disease and methodologies to treat these phenotypes (Table 1). It should be noted that this disease classification is simplified based on angiographic appearance of the trifurcation, and does not take into account the high likelihood that trifurcation disease can be diffuse, involving all three branches, as can be observed on intravascular ultrasound of these vessels. Furthermore, the various treatment methodologies will need to be validated by outcome studies, and it is not clear at this time how aggressive one should be with stenting of all branches (YV2, VT, CT, V2) versus applying a provisional stenting concept (YV, TB, VB). Our favorite techniques for Type A lesions are the VT and YV2 techniques, and for Type B, we prefer the VB and V2 techniques. In part II of this report, we will report on a total of 23 consecutive patients with trifurcation stenting performed at our institution in 2005 and discuss their long-term outcomes. Finally, treatment of trifurcating disease is complex and requires a set of skills available only to a limited number of interventionalists. Therefore, treatment of trifurcating disease should be limited to high-volume, experienced operators in large centers. Acknowledgment. The author wishes to acknowledge Lynne Majetic for her superb artistic work in drawing the figures in this manuscript.

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