A Novel Descriptive, Intelligible and Ordered (DINO) Classification of Coronary Bifurcation Lesions

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1 Circulation Journal Official Journal of the Japanese Circulation Society ORIGINAL ARTICLE Cardiovascular Intervention A Novel Descriptive, Intelligible and Ordered (DINO) Classification of Coronary Bifurcation Lesions Review of Current Classifications Shams Y-Hassan, MD; Magnus C Lindroos, MD, PhD; Christer Sylvén, MD Background: Several classification systems for coronary artery bifurcation lesions (CABL) have been described in the literature, but despite the commendable effort to simplify a difficult subject in interventional cardiology, all of them have certain limitations and shortcomings. Methods and Results: The proposed Descriptive, INtelligible and Ordered (DINO) is a new descriptive and clinically oriented system of classifying CABLs. This classification system takes into consideration more details of the side branch angulation relative to the main branch. It uses self-explanatory terms and mnemonic characters (acronyms related to the branches of the bifurcation and the shape of side branch angulation). The DINO classification describes the extent of CABL distribution and designates its localization at the bifurcation region. Moreover, systematized simple and easy to remember terms may form a relevant classification basis for multicenter and meta-analysis investigations. Conclusions: The DINO is the first verbally anchored, all-inclusive classification system of CABLs. It describes precisely side branch angulation, using self-explanatory and instructive terms that describe both the extent of the lesion s distribution and its localization. The current coronary bifurcation lesion classifications are reviewed. (Circ J 2011; 75: ) Key Words: Bifurcation classification; Coronary bifurcation; Coronary stenosis; Percutaneous coronary intervention; Stenting technique Coronary artery bifurcation stenosis and some other coronary lesions, such as unprotected left main stem stenosis, multivessel disease and chronic total occlusion, are among the challenging lesions for percutaneous coronary intervention (PCI). 1 5 A proper analysis and classification of both the lesion s localization at the coronary bifurcation site and the side branch (SB) angulation are crucial in individualizing the PCI technique for the treatment of coronary bifurcation stenosis. Several coronary artery bifurcation lesion (CABL) classification systems have been described in the literature. 1,2,6 13 All of them are praiseworthy attempts to simplify a hard topic in interventional cardiology, but nevertheless, they have certain limitations and shortcomings. Not only do the terms used for lesion types not give information about the extent of the lesion s distribution and its localization at site of the bifurcation, they are also difficult to memorize and communicate. Some of the classifications do not cover all categories of bifurcation lesion. Currently, the most commonly applied classification of bifurcation lesions is that proposed by Medina et al, which uses a binary number system for each branch of the bifurcation, but does not consider the bifurcation angle. 11 Herein, we propose the Descriptive, INtelligible and Ordered (DINO), a new verbally anchored, self-descriptive classification system that gives information about the SB angulation relative to the main branch (MB) and about the extent of lesion distribution and its localization. Editorial p 263 Methods and Results The DINO Classification of CABLs Definitions The coronary artery bifurcation has 3 segments (Figure 1): 2 from the MB (the proximal MB (PMB) and the distal MB (DMB)) and the 3rd segment is the SB. These 3 branches of the bifurcation form 3 forks: (1) the MB fork formed by the PMB and the DMB; (2) the proximal fork formed by the PMB and the SB; and (3) the distal fork formed by the DMB and the SB. The most important regions of a coronary bifurcation in the setting of coronary angioplasty are the ostial regions (the ostium and the adjacent few Received July 5, 2010; revised manuscript received September 9, 2010; accepted October 1, 2010; released online December 24, 2010 Time for primary review: 62 days Department of Cardiology, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden Mailing address: Shams Y-Hassan, MD, Department of Cardiology, Karolinska University Hospital, Huddinge, S Stockholm, Sweden. shams.younis-hassan@karolinska.se ISSN doi: /circj.CJ All rights are reserved to the Japanese Circulation Society. For permissions, please cj@j-circ.or.jp

2 300 Y-HASSAN S et al. Figure 1. Definitions of the various components of a coronary artery bifurcation. Figure 2. Schematic (A) and angiographic images (B) illustrating the Descriptive, Intelligible and Ordered (DINO) classification system of a coronary artery bifurcation based on the SB angulation relative to the DMB. PMB, proximal main branch; DMB, distal main branch; SB, side branch; LAD, left anterior descending artery; LMS, left main stem; LCx, left circumflex artery.

3 DINO Classification of Bifurcation Lesions 301 Figure 3. Schematic (A) and angiographic images (B) show the Descriptive, Intelligible and Ordered (DINO) classification system of coronary artery bifurcation lesions according to the extent of lesion distribution and its localization. The angiographic images show LAD/diagonal branch bifurcation stenosis. Arrows show the stenotic regions. PDS (proximal + distal + side branch); PD (proximal + distal); PS (proximal + side branch); DS (distal + side branch); P, proximal; D, distal; S, side branch.

4 302 Y-HASSAN S et al. Table 1. DINO Classification in Both Words and Mnemonic Characters DINO classification DINO classification (words) (mnemonic letters) Tri-ostial (Y, T, or R) PDS (Y, T, or R) Bi-ostial Main branch bi-ostial (Y, T, or R) PD (Y, T, or R) Proximal bi-ostial (Y, T, or R) PS (Y, T, or R) Distal bi-ostial (Y, T, or R) DS (Y, T, or R) Mono-ostial Proximal mono-ostial (Y, T, or R) P (Y, T, or R) Distal mono-ostial (Y, T, or R) D (Y, T, or R) Side branch mono-ostial (Y, T, or R) S (Y, T, or R) Y, T, and R denote Y-, T-, and reverse-shaped side branch angulation, respectively. PDS (proximal + distal + side branch); PD (proximal + distal); PS (proximal + side branch); DS (distal + side branch). DINO, Descriptive, INtelligible and Ordered; P, proximal; D, distal; S, side branch. Table 2. Lesion Distribution and Localization at the Coronary Bifurcation Percentage according to the DINO classification lesion localization 12 (n=465) Tri-ostial (PDS) 43.0% Bi-ostial Main branch bi-ostial (PD) 15.7% Proximal bi-ostial (PS) 2.2% Distal bi-ostial (DS) 7.3% Mono-ostial Proximal mono-ostial (P) 7.1% Distal mono-ostial (D) 17.6% Side branch mono-ostial (S) 7.1% PDS (proximal + distal + side branch); PD (proximal + distal); PS (proximal + side branch); DS (distal + side branch). Abbreviations see in Table 1. millimeters in the respective segment) of the 3 segments. For simplification and practical reasons, the first few adjacent millimeters of the PMB to the bifurcation site are regarded as an ostial region beside the other 2 ostial regions of the DMB and the SB. The 3 ostial regions (PMB, DMB and the SB) constitute the bifurcation region. An ostial lesion is defined as an atherosclerotic plaque involving the ostial region of 1 or more of the bifurcation branches. These lesions may even extend more proximally in the PMB or more distally in the DMB or the SB. CABLs are classified in DINO according to: 1. The angulation of the SB relative to the MB. 2. The extent of the lesion s distribution and its localization at the bifurcation region. These 2 factors determine the feasibility of guidewire access to both branches, the rate of procedural success and complications. They also influence the choice of the approach strategy used in PCI. The DINO Classification According to SB Angulation The bifurcation angle is defined as the angle between the axis of the most proximal part of the SB and the axis of the DMB. Based on this angulation, coronary artery bifurcations are classified into 3 groups (Figure 2): 1. Y-shaped angulation (acute angulation) in which the angle between the SB and the DMB is < T-shaped angulation (right or near-right angulation) in which the angle between the SB and the DMB is Reverse-shaped angulation (obtuse angulation) in which the angle between the SB and the DMB is >90. Guidewire access is easy in a Y-shaped angulation, but difficult in T-shaped angulation. There is a prominent risk of plaque and even carina shift during PCI in a Y-shaped angulation, but the risk of plaque shift is minimal in a T-shaped angulation. The reverse-shaped angulation carries the disadvantages of both extreme difficulty with SB wire access and the prominent risk of plaque shift toward the SB ostium during PCI. SB angulation also has a great impact on the complexity of the stenting technique, particularly when the SB is diseased and supplies a substantial region of the myocardium. 2,10 The DINO Classification According to the Distribution and Localization of the Bifurcation Lesion Based on the extent of the atherosclerotic lesion s distribution and its localization at the bifurcation region, CABLs are classified according to the number of ostial regions involved and localization at the branch(es) of the bifurcation. This is done in an ordered pattern beginning from the most extensive lesion to the least extensive; from the proximal to the distal branch and from the MB to the SB. Consequently, the DINO classification according to lesion distribution and localization at the bifurcation region is as follows (Figure 3): 1. Tri-ostial coronary artery bifurcation stenosis: the atherosclerotic lesion involves all 3 ostial regions of the bifurcation. 2. Bi-ostial coronary artery bifurcation stenosis, subdivided into 3 groups: a. MB (fork) bi-ostial: the atherosclerotic lesion involves the ostial regions of both the PMB and the DMB (ie, the branches of the MB fork). The ostial region of the SB is spared. b. Proximal (fork) bi-ostial: the atherosclerotic lesion involves the ostial regions of both the PMB and the SB (ie, the branches of the proximal fork). The ostial region of the DMB is spared. c. Distal (fork) bi-ostial: the atherosclerotic lesion involves the ostial regions of both the DMB and the SB (ie, the branches of the distal fork). The ostial region of the PMB is spared. 3. Mono-ostial coronary artery bifurcation stenosis, subdivided into 3 groups: a. Proximal mono-ostial: the atherosclerotic lesion involves only the PMB ostial region. b. Distal mono-ostial: the atherosclerotic lesion involves only the DMB ostial region. c. SB mono-ostial: the atherosclerotic lesion involves only the SB ostial region. Description of a Bifurcation Lesion According to the DINO Classification System The bifurcation lesion is described first by localization either in words (tri-ostial, bi-ostial, or mono-ostial) or mnemonic letters (P for PMB, D for DMB, S for SB), followed by the shape of the SB angulation (Y for the Y-shaped, T for the T-shaped, R for the Reverse-shaped angulation). For example, a tri-ostial T (PDS T) lesion denotes a bifurcation lesion involving all 3 ostial regions of a bifurcation with T-shaped SB angulation (Table 1). The distribution of lesion type according to lesion localization is demonstrated in Table 2.

5 DINO Classification of Bifurcation Lesions 303 Figure 4. Overview of the currently available coronary artery bifurcation lesion classifications. ( ) Lesion category is not included. *a, large SB; d, small SB. Movahed classification 13 according to Figure 1 in reference 13 in which it is clear that in the bifurcation categories L, S, 2, V and T, the lesions involve the PMB, the DMB and the SB. In that figure, the authors take into consideration the size of the PMB, large (L) or small (S), and the angle between branch vessels: <70 (V) or >70 (T). The most common type of coronary bifurcation lesion is the tri-ostial lesion. 12 Regarding SB angulation, Y-shaped angulation constitutes 76.1% and T-shaped angulation 23.9% of lesions. 10 The reverse-shaped angulation is not well studied and hitherto most probably included in the T-shaped angulations. Discussion Review of Current Coronary Bifurcation Classifications To the best of our knowledge, there are 8 classification systems of coronary bifurcation lesions that have been reported in the literature (Figure 4). 1,2, George et al (1986) 6 reported on the feasibility of the kissing balloon technique in balloon angioplasty of coronary bifurcation lesions. 6 They described 4 types of bifurcation stenosis (types a, b, c, and d). In type a lesion, the disease involved the PMB, DMB and the ostium of a large SB. Atherosclerotic disease involved both the PMB and the DMB, but not a large SB, in a type b lesion. In type c lesions, the disease involved only the PMB. In a type d lesion, the disease involved the PMB, DMB and the SB, but the SB was small and not able to be surgically bypassed. The take-off angle between the SB and the MB was not considered. 2. According to the Duke s classification, 7 coronary bifurcation lesions are classified into 6 types: A, B, C, D, E and F involving the PMB, DMB, PMB plus DMB, all 3 bifurcation branches, the SB, and PMB plus SB, respectively (Figure 4). The lesion involving the combination of the DMB and the SB is missing and the Duke s classification does not consider SB angulation. 3. Spokojny and Sanborn 8 classified bifurcation lesions into 5 types (I, II, III, IV, and V). 8 In a type I lesion, also called a true bifurcation lesion, the disease involves all 3 ostial regions of the bifurcation. Type II bifurcation lesion affect only the MB. Both the DMB and the SB are affected in a type III lesion. Type IV lesions involve only the PMB and type V lesions involve only the SB ostial region. This classification does not include combinations of lesions (lesions involving the PMB plus the SB) or lesions involving only the DMB, nor is SB angulation is considered. 4. Safian 9 classified lesions at the bifurcation site into 4 types (types 1 4). The first 3 types are classified according to which ostial region(s) of the MB is involved. Types 1, 2 and 3 are further subdivided into A (involving both the MB and the SB) and B (involving only the MB). In type 4, the lesion involves only the SB. This classification covers all combinations of lesion affecting a bifurcation site but does not consider SB angulation. 5. Lefevre et al 10 classified coronary bifurcation lesions into 6 types (1, 2, 3, 4, 4A, 4B). The type 1 lesion was defined as a true bifurcation lesion involving all 3 ostial regions. Type 2 lesions involve both the PMB and the DMB ostial regions but not the SB. Type 3 lesions involve only the PMB.

6 304 Y-HASSAN S et al. Type 4 lesions are subdivided into 3 types: a type 4 lesion involves the ostial regions of both the DMB and the SB, a type 4A lesion involves only the DMB and a type 4B lesion involves only the SB. This classification does not consider lesion affecting both the PMB and the SB. It takes into account SB angulation as either Y-shaped or T-shaped. For Y-shaped angulation, the angle between the DMB and the SB is <70 and in T-shaped angulation, the angle is > Medina et al, 11 in their classification of bifurcation lesions, used the 3 components of a bifurcation: the PMB, DMB and the SB. Their system consists of allocating a binary value (1,0) according to whether or not each segment is compromised. They classified bifurcation lesions into 7 combinations: (1) Medina 1,1,1 lesion involves all 3 ostial regions; (2) Medina 1,1,0 lesion involves the PMB and the DMB, the SB is spared; (3) Medina 1,0,1 lesion involves the PMB and the SB, the DMB is spared; (4) Medina 0,1,1 lesion involves the DMB and the SB, the PMB is spared; (5) Medina 1,0,0 lesion involves only the PMB; (6) Medina 0,1,0 lesion involves only the DMB; (7) Medina 0,0,1 lesion involves only the SB. The Medina classification does not consider SB angulation. 7. Tsuchida et al 12 reported on the clinical outcome of percutaneous treatment with a sirolimus-eluting stent of bifurcation lesions in multivessel coronary artery disease. Plaque distribution was described on the basis of SYNTAX score bifurcation lesion type and classified into 7 types (A, B, C, D, E, F, and G). The take-off angle of the SB is measured by visual assessment in a non-foreshortened projection. According to the plaque distribution, the lesions are defined as follows: type A lesion involves only the PMB; type B lesion involves only the DMB; type C lesion involves both the PMB and the DMB; type D lesion involves all the branches of the bifurcation; type E lesion involves only the SB ostial region; type F lesion involves the PMB and the SB; type G lesion involves the DMB and the SB. 8. Movahed et al 13 proposed a classification system that uses a combination of letters and numbers to provide an anatomic description of a given coronary bifurcation lesion. This classification system consists of the prefix B (for bifurcation), followed by the addition of 4 separate suffixes. The first suffix consists of letter C (close to the bifurcation), N (bifurcation lesion with 1 branch being nonsignificant defined as <2.0 mm vessel diameter), S (small proximal segment), or L (large proximal segment defined as more than two-thirds of the sum of the diameters of both branch vessels). The second suffix describes the number of diseased ostia, where 1M denotes that only the main vessel ostium is involved; 1S only the SB ostium is involved; or 2 both ostia are involved. The third suffix considers the angle between the bifurcation vessels and uses the letter V (the angle between the 2 branches is <70 ) or T (the angle between the 2 branches is >70 ). The fourth suffix is optional: CA for calcified, LM for the left main involvement. To sum up, all the existing classifications take into account plaque distribution and localization at the bifurcation site, but only a few of them consider the SB angulation relative to the MB. Only a few of the current classifications cover all 7 combinations of coronary bifurcation lesions. All of the current classification systems use abstract letters, numbers or a combination of both. These letters and numbers are unrelated to the lesions characteristics and give no information about distribution or localization. The DINO Classification According to SB Angulation Based on the SB takeoff angulation relative to the DMB, a new group, the reverse-shaped (obtuse) angulation (Figure 2), is added to the previously well-known Y- and T-shaped angulation groups for the reason that such a group of SB angulation exists and may cause difficulties during PCI. 14 This type of angulation is important to recognize because it has both the risk of plaque shift that exists with Y-shaped SB angulation, and the guide wire access difficulties present with T-shaped SB angulation. Interestingly, reverse-shaped angulation combined with a lesion in the PMB ostial region of the bifurcation (proximal mono-ostial stenosis) is actually advantageous when using the newly reported PCI technique. 15 The DINO Classification According to the Distribution and Localization of the Bifurcation Lesion As mentioned earlier and to the best of our knowledge, 8 CABL classifications and definitions have been described in the literature (Figure 4) Some of these clearly define most of the possible combinations of bifurcation lesions, 9,11,12 but all the currently available classifications have weaknesses and limitations. The majority categorize bifurcation lesions into types identified by abstract numbers or letters without obvious associations with anatomical localization and lesion distribution According to these classifications, identical bifurcation lesions will have different letters or numbers, which may unnecessarily complicate and confuse communication. Some of the classifications lack certain types of bifurcation lesions (Figure 4). 6 8,10,13 It is, in our view, important that a bifurcation classification system covers all lesion categories with well-defined SB angulation in order for the operators to individualize PCI techniques for each patient. 1,2,15 22 The new DINO classification system of CABLs uses verbally anchored, plain and self-evident terms that describe the extent of the lesion s distribution (tri-, bi-, or mono-ostial lesions). The selection of terms to indicate the anatomical localization of the lesion at the bifurcation region is very simplified: putting the name of the branch (proximal, distal or SB) before the mono-ostial lesion and the name of the fork (MB, proximal or distal) before the bi-ostial lesion. A triostial bifurcation lesion is a self-explanatory term. For these reasons, this new classification is, in our opinion, easy to memorize and communicate, covers all the combinations of lesions involving the bifurcation region and may form the basis of a relevant classification for multicenter and metaanalysis investigations. Among the previous bifurcation classification systems, with regard to the extent of the bifurcation lesion s distribution and its localization, the closest to the DINO is the Medina classification. Medina et al, in their classification, give a binary value 1 (diseased) or 0 (undiseased) to each of the 3 segments of the bifurcation. That classification covers absolutely all categories of bifurcation lesion, but the DINO classification, in our opinion, has some advantages over the Medina classification. It considers the bifurcation angle between the MB and the SB in detail and has added a new category of bifurcation angle (the reverse-shaped angle) with its clinical implications and the feasibility of certain PCI techniques. 15 The Medina classification does not take into account SB angulation. Concerning lesion distribution and localization, both the DINO and Medina classifications covers all lesion distributions and are easy to remember. The advantage of the DINO over the Medina classification in this regard is that the DINO defines the lesion categories by descriptive words and mnemonic letters that are easily understood instead by the abstract num-

7 DINO Classification of Bifurcation Lesions 305 bers used in the Medina classification. Conclusion The DINO classification system of CABLs is the first verbally anchored, all-inclusive classification system. It is simple, instructive, and requires little effort to memorize. It describes precisely the SB angulation, which has a great impact on the complexity of the PCI procedure and the choice of treatment strategy. It uses self-explanatory terms that describe both the extent of the lesion s distribution and its localization. Acknowledgment This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. The authors have no conflicts of interest. References 1. Louvard Y, Thomas M, Dzavik V, Hildick-Smith D, Galassi AG, Pan M, et al. Classification of coronary artery bifurcation lesions and treatments: Time for a consensus! Catheter Cardiovasc Interv 2008; 71: Iakovou I, Ge L, Colombo A. Contemporary stent treatment of coronary bifurcations. J Am Coll Cardiol 2005; 46: Cheng CI, Lee FY, Chang JP, Hsueh SK, Hsieh YK, Fang CY, et al. Long-term outcomes of intervention for unprotected left main coronary artery stenosis: Coronary stenting vs coronary artery bypass grafting. Circ J 2009; 73: Yamagata K, Kataoka Y, Kokubu N, Kasahara Y, Abe M, Nakajima H, et al. A 3-year clinical outcome after percutaneous coronary intervention using sirolimus-eluting stent and off-pump coronary artery bypass grafting for the treatment of diabetic patients with multivessel disease. Circ J 2010; 74: Lee SP, Kim SY, Park KW, Shin DH, Kang HJ, Koo BK, et al. Long-term clinical outcome of chronic total occlusive lesions treated with drug-eluting stents: Comparison of sirolimus-eluting and paclitaxel-eluting stents. Circ J 2010; 74: George BS, Myler RK, Stertzer SH, Clark DA, Cote G, Shaw RE, et al. Balloon angioplasty of coronary bifurcation lesions: The kissing balloon technique. Cathet Cardiovasc Diagn 1986; 12: Pompa J, Bashore T. Qualitative and quantitative angiography: Bifurcation lesions. In: Topol E, editor. Textbook of interventional cardiology. Philadelphia: WB Saunders, 1994; Spokojny AM, Sanborn TM. The bifurcation lesion. In: Ellis SG, Holmes DR, editors. Strategic approaches in coronary intervention. Baltimore: Williams and Wilkins, 1996; Safian RD. Bifurcation lesions. In: Safian RD, Freed MS, editors. The manual of interventional cardiology. Royal Oak, MI: Physician s Press, 2001; Lefevre T, Louvard Y, Morice MC, Dumas P, Loubeyre C, Benslimane A, et al. Stenting of bifurcation lesions: Classification, treatments, and results. Catheter Cardiovasc Interv 2000; 49: Medina A, Suarez de Lezo J, Pan M. A new classification of coronary bifurcation lesions. Rev Esp Cardiol 2006; 59: 183 (in Spanish). 12. Tsuchida K, Colombo A, Lefevre T, Oldroyd KG, Guetta V, Guagliumi G, et al. The clinical outcome of percutaneous treatment of bifurcation lesions in multivessel coronary artery disease with the sirolimus-eluting stent: Insights from the Arterial Revascularization Therapies Study part II (ARTS II). Eur Heart J 2007; 28: Movahed MR, Kern K, Thai H, Ebrahimi R, Friedman M, Slepian M. Coronary artery bifurcation lesions: A review and update on classification and interventional techniques. Cardiovasc Revasc Med 2008; 9: Pflederer T, Ludwig J, Ropers D, Daniel WG, Achenbach S. Measurement of coronary artery bifurcation angles by multidetector computed tomography. Invest Radiol 2006; 41: Y-Hassan S, Lindroos MC, Sylvén C. A novel stenting technique for coronary artery bifurcation stenosis. Catheter Cardiovasc Interv 2009; 73: Schwartz L, Morsi A. The draw-back stent deployment technique: A strategy for the treatment of coronary branch ostial lesions. J Invasive Cardiol 2002; 14: Dardas PS, Tsikaderis DD, Mezilis NE, Styliadis G. A technique for type 4a coronary bifurcation lesions: Initial results and 6-month clinical evaluation. J Invasive Cardiol 2003; 15: Colombo A, Gaglione A, Nakamura S, Finci L. Kissing stents for bifurcational coronary lesion. Cathet Cardiovasc Diagn 1993; 30: Schampaert E, Fort S, Adelman AG, Schwartz L. The V-stent: A novel technique for coronary bifurcation stenting. Cathet Cardiovasc Diagn 1996; 39: Szabo S, Abramowitz B, Vaitkus PT. New technique for aorto-ostial stent placement. Am J Cardiol 2005; 96: 212H. 21. Applegate RJ, Davis JM, Leonard JC. Treatment of ostial lesions using the Szabo technique: A case series. Catheter cardiovasc Interv 2008; 72: Habara M, Kinoshita Y. Stenting with protruding strut into side branch (SPRINT) technique: A novel technique for coronary bifurcation stenting. Catheter Cardiovasc Interv 2009; 73: