Bifurcations

As the summer holidays wind down to the final few days, many of us are heading back to the routine of work, school and home. With the end of summer, my Bifurcation Series comes to a close as well. The final episode is the TAP technique.

Operators find this to be the least cumbersome of all the 2-stent strategies. Many resort to it during emergencies as the access to the main branch (MB) is maintained throughout the procedure. The steps are fewer which ensures expeditious coverage of both vessels followed by the conventional optimization steps including kissing and proximal optimization with a non-compliant balloon. Similar to culotte, this strategy allows operators to start with a provisional strategy and convert to TAP should the need arise. In addition, there is minimal stent overlap. This technique is considered a modification of what was formally known as T-stenting. The primary limitation of the original T-stenting was missing the ostium of the side branch (SB). This geographic miss is what prompted many operators to perform minimal protrusion to mitigate in-stent restenosis at that missed segment. Hence the name TAP, T and small protrusion, was coined. Although this technique has been adopted worldwide, there are no large randomized trials with long term outcome data to reference. There are some published data; however, that are worth reviewing.

Study	TAP strategy	Patients (n)	Unprotected left main stem	Follow-up duration	TVR	Definite stent thrombosis
Burzotta et al’	Bail-out TAP in provisional	73	37.0%	9 months	6.8%	1.40%
Al Rashdan et al7	Systematic TAP	156	10.3 %	36 months (range 24-48 months)	5.3%	0.06%
Burzotta et a1	Bail-out TAP in provisional procedures	19	5.0%	12 months	5.3%	none
Naganuma et al	Bail-out TAP (type B dissection or TlMI <3 or stenosis >50% in the SB)	95	18.9%	36 months	9.7%	none
ARTEMIS study10	Bail-out TAP (type B dissection or TlMI <3 or stenosis >75% in the SB)	71	26.8%	12 months	8.5%	none
SB:side branch;TVR: target vessel revascularisation

Burzotta et al, 2007

The modification of the T-stenting was first described in 2007 by Burzotta et al.¹ It was evaluated in vitro and in two independent series of patients undergoing elective drug-eluting stent (DES) implantation on a bifurcation lesion. In vitro testing demonstrated perfect coverage of the bifurcation with minimal stent’s struts overlap at the proximal segment of SB ostium with a single layer stent struts. Sirolimus, paclitaxel, or zotarolimus DES were deployed in 73 patients (67% with Medina 1,1,1 lesions and 44% of unprotected distal left main disease) using the TAP technique. The procedural success was achieved in all cases. At 9 months the clinically-driven target vessel revascularization (TVR) was 6.8%. Since this was a pilot study, the investigators recommended larger outcome trials to further evaluate this technique. No comparison arm was available in this initial trial.

Al-Rashdan et al, 2009

In 2009 Al-Rashdan et al published their series of 156 consecutive patients who underwent TAP stenting.² This was a single center study that resulted in a 99% procedural success rate and a major adverse cardiac events (MACE) free survival rate of 88% at 36 months average follow up. The TVR rate was 5.3%. Although to date this represents the largest cohort of TAP cases, the results are limited to a single center with no randomization which precludes further conclusions.

Burzotta et al, 2009

In 2009, Burzotta’s group prospectively enrolled 266 consecutive patients requiring treatment of a bifurcation lesion.³ The MB was treated with a DES and TAP was reserved as a bailout strategy. Only 19 of the total required a bailout 2-stent strategy. Nine percent of the total had unprotected left main disease. At one year, the MACE rate was 8.2%. A non-hierarchical analysis revealed a 0.4% cardiac death, 4.1% MI, 4.5% TVR and 2 of the total had probable stent thrombosis (ST). Given the small number of bailout 2-stent strategy arm, this study only demonstrates safety.

Naganuma et al, 2013

Naganuma et al retrospectively analyzed data of all patients who underwent TAP technique with DES between July 2005 and January 2012.⁴ A total of 95 patients were enrolled. Angiographic procedural success was achieved in all cases. A true bifurcation was found in 78.9% of those enrolled. The 3-year MACE, cardiac death or myocardial infarction, TVR and target lesion revascularization (TLR) rates were 12.9%, 3.1%, 9.7%, and 5.1%, respectively. No ST was observed in this cohort. Once again, the investigators recommend larger trials to make solid recommendations.

Naganuma et al, JACC Cardiovasc Interv. 2013;6:554-61.

ARTEMIS Study 2014

The ARTEMIS study was published in 2014.⁵It evaluated the mid-term angiographic results of TAP as the bailout strategy in symptomatic patients who were treated with one-stent strategy (DES of the MB) and kissing balloon inflation of the SB who subsequently developed impingement of the branch. TAP was performed if residual diameter stenosis of SB was ≥75%, presence of ≥type B dissection or flow impairment of the SB occurred. A total of 71 patients were enrolled with a MEDINA classification 1,1,1 lesions occurring in 60% of the total. At 9 months, restenosis was occurred in 12.5% of the total. Late lumen loss in the MB and SB was 0.22 ± 0.19 and 0.34 ± 0.37 mm, respectively.

Dzavik et al, 2014

In 2014, there was much hype revolving around bioresorbable technology. Dzavik et al performed in vitro bifurcation stenting employing different modalities on synthetic arterial models.⁶ The everolimus-eluting bioresorbable vascular scaffold (Abbott Vascular, Santa Clara, California) (BVS) was used. A low-pressure final kissing balloon inflation was performed to complete the procedures. The results demonstrated that a single-stent technique optimally opened the SB without deforming the BVS in the MB. T or TAP-stenting covered the SB ostium completely. Culotte and crush with 2 BVS stents was successful; however, disruption was reported after the low pressure kissing inflation in one case. Investigators concluded that it was feasible to perform bifurcation stenting with BVS in large caliber vessels. They also recommended that a provisional strategy as the default. TAP or T-stenting with a metal DES is preferable. As the overall in vivo outcome data for BVS remains cautionary at best, the use of BVS outside clinical trials is not recommended whether for focal type A lesions or complex bifurcations.

The technique itself is illustrated below. As mentioned earlier, it is one of the simpler 2-stent strategies. Like other strategies, appropriate sizing, positioning and optimization ultimately dictate the final angiographic and clinical outcomes. Intracoronary imaging facilitates these crucial steps. Yet, as with all interventions, judgment is the cornerstone of any successful procedure. When appropriate, and based on both Syntax score and clinical scores, surgical revascularization should be considered. When one opts for percutaneous revascularization, the indication for the procedure, its potential risks and complexity should be shared with the patient. For operators, judging the significance of the SB, the angle of the bifurcation, the size of both vessels and the need for mechanical circulatory support is valuable. Finally, complex bifurcation stenting is not for everyone. When appropriate, such complex procedures should be referred to expert operators for the best outcomes.

Animations/illustrations courtesy of Graphic Designer Dania Al-Shaibi

Email: [email protected]

References:

Burzotta F, Gwon HC, Hahn JY, Romagnoli E, Choi JH, Trani C, Colombo A. Modified T-stenting with intentional protrusion of the side-branch stent within the main vessel stent to ensure ostial coverage and facilitate final kissing balloon: the T-stenting and small protrusion technique (TAP-stenting). Report of bench testing and first clinical Italian-Korean two-centre experience. Catheter Cardiovasc Interv.2007;70:75-82.
Al Rashdan I, Amin H. Carina modification T stenting, a new bifurcation stenting technique: clinical and angiographic data from the first 156 consecutive patients. Catheter Cardiovasc Interv.2009;74:683-90.
Burzotta F, Sgueglia GA, Trani C, Talarico GP, Coroleu SF, Giubilato S, Niccoli G, Giammarinaro M, Porto I, Leone AM, Mongiardo R, Mazzari MA, Schiavoni G, Crea F. Provisional TAP-stenting strategy to treat bifurcated lesions with drug-eluting stents: one-year clinical results of a prospective registry. J Invasive Cardiol.2009;21:532-7.
Naganuma T, Latib A, Basavarajaiah S, Chieffo A, Figini F, Carlino M, Montorfano M, Godino C, Ferrarello S, Hasegawa T, Kawaguchi M, Nakamura S, Colombo A. The long-term clinical outcome of T-stenting and small protrusion technique for coronary bifurcation lesions. JACC Cardiovasc Interv. 2013;6:554-61.
Jim MH, Wu EB, Fung RC, Ng AK, Yiu KH, Siu CW, Ho HH. Angiographic result of T-stenting with small protrusion using drug-eluting stents in the management of ischemic side branch: the ARTEMIS study. Heart Vessels.2014 Mar 14.
Dzavik V, Colombo A. The absorb bioresorbable vascular scaffold in coronary bifurcations: insights from bench testing. JACC Cardiovasc Interv.2014;7:81-8.

Approximately 15-20% of all coronary interventions are bifurcations¹. Based on the overall Syntax Score, coronary artery bypass grafting is often recommended particularly in the setting of multi-vessel disease, diabetes and impaired left ventricular function. Once a decision to proceed with percutaneous revascularization is made, it is imperative that operators select the most appropriate revascularization strategy suited for an individual patient.

Briefly, the published data still recommends a provisional strategy as the default¹. Of course, a two-stent strategy is commonly employed for bail out. An up-front two stent strategy is reserved for the following:

This strategy is recommended for true Bifurcation Lesions with a Medina (111,011,101). This is of importance if the lesion is long and extends > 5-10 mm beyond the ostium of a sizeable side branch (> 2.5mm).
If the side branch is very large, poor myocardial reserve, and a high jeopardy score, the hemodynamic consequences may be significant warranting revascularization of the side branch.
Finally, if the angle to the side branch is acute rendering access too difficult, it is advisable to proceed with a two-stent strategy.

Over the course of the next couple of blogs, I will briefly review the randomized trials and steps of the different strategies. This month, my focus will be on DK-Crush.

DK Crush II was a randomized trial comparing DK-Crush to provisional stenting in symptomatic patients with a Medina 1,1,1 or 0,1,1 lesion. One-hundred and eight five were enrolled in each arm. The primary endpoint was major adverse cardiac events (MACE), namely cardiac death, MI and target vessel revascularization (TVR) at 5 years. It concluded that DK-Crush was associated with a lower 5-year MACE rate compared to provisional stenting.

Chen et al. Circ Cardiovasc Interv 2017;10:e 004497

DK Crush III was a randomized trial comparing DK-Crush to Culotte stenting in symptomatic patients with a distal Left Main lesion that is Medina 1,1,1 or 0,1,1. Approximately, 210 were enrolled in each arm. The primary endpoint was a composite of MACE and TVR at 3 years. It concluded that DK-Crush was associated with a lower 3-year MACE rate compared to Culotte stenting.

3-years outcome	DK crush	Culotte	p-value
Death %	1.4	2.9	0.34
MI %	3.4	8.2	0.037
TVR %	5.8	18.8	<0.001
Definite ST %	0	3.4	0.007

Chen et al. JACC. Cardiovasc. Interv 2015;8:1335-42

DK Crush V was a randomized trial comparing DK-Crush to a provisional strategy in symptomatic patients with a distal Left Main lesion that is Medina 1,1,1 or 0,1,1. It enrolled approximately 240 patients in each arm. The primary endpoint was target lesion failure defined as cardiac death, target vessel myocardial infarction or target lesion revascularization at 12 months. It concluded that DK-Crush was superior at 12 months.

Chen et al. J Am Coll Cardiol. 2017;70:2605-17

The steps of this technique can be summarized in the illustration (Image A). It is noteworthy, that critical steps in any bifurcation technique include intracoronary imaging and proximal optimization (POT). Imaging allows appropriate determination of size of the vessels in question, length of the disease and characterization of the lesion before the planned strategy. It, therefore, permits the operator to perform the necessary lesion preparation if calcified. Upon completion of the procedure, imaging allows appropriate evaluation of the stent expansion and apposition with additional post-dilatation if need be. Proximal optimization is a fundamental step irrespective of the technique adopted. It permits the operator to expand the main branch stent to facilitate the remainder of the steps, prevent the wire from entering behind the stent struts, prevent stent compression and ultimately permit appropriate stent apposition. This in itself facilitates future intervention and reduces stent thrombosis. Many have added an additional POT before the second kissing inflation to facilitate crossing into the SB. It is important that fluoroscopic imaging is sharp to allow appropriate positioning of the non-compliant balloon at the proximal stent edge and at the neo-carina. Several techniques including “Stent Boost” and “Clear Stent” specific to each vendor are readily available. Finally, given the multiple steps in bifurcation stenting, radiation safety is imperative for any and all techniques.

Image: Steps of DK Crush