Percutaneous Revascularisation of Coronary Chronic Total Occlusion - Outcomes and Development of Strategy 2006-2010

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Abstract

Percutaneous coronary intervention for chronic total occlusions (CTOs), the most difficult and time-consuming intervention, is evolvingrapidly. There has been a well-documented increase in the success rate of procedures in the hands of specifically trained operators fromabout 60 % to 90 % over the past 10 years; at the same moment the long-term patency with drug-eluting stents is exceeding 90 %. Theseresults are comparable or even superior to surgical revascularisation. Several sophisticated techniques unique to CTO interventions aredescribed in this article and the need for specific training is emphasised so that a success rate of at least 80 % can be met, as claimedby the European Society of Cardiology guidelines on myocardial revascularisation, and so that patients with CTO who deserverevascularisation are no longer denied appropriate treatment.

Acknowledgements: The author appreciates the tremendous work of the members of the EuroCTO club, who supplied their data through the European Registry ofChronic Total Occlusion, and also the help of Dimitri Krasnokoutski who assisted with extracting the results. The following members enrolled more than 300 cases during2008–2010: Nicolaus Reifart, Bad Soden, Germany; Georgios Sianos, Thessaloniki, Greece; Alfredo R Galassi, Catania, Italy; Gerald Werner, Darmstadt, Germany.

Disclosure
The author has no conflicts of interest to declare.
Correspondence
Nicolaus Reifart, Main Taunus Heart Institute, 65812 Bad Soden, Germany. E: n.reifart@reifart-partner.de
Received date
28 June 2011
Accepted date
21 July 2011
Citation
ICR - Volume 6 Issue 2;2011:6(2):128-133
Correspondence
Nicolaus Reifart, Main Taunus Heart Institute, 65812 Bad Soden, Germany. E: n.reifart@reifart-partner.de
DOI
http://dx.doi.org/10.15420/icr.2011.6.2.128

Definition and Prevalence

Nowadays it is widely accepted to define chronic total occlusions (CTOs) of the coronary artery as lesions with thrombolysis in myocardial infarction 0 flow for more than three months (either angiographically proven or with high clinical likelihood).1 Occlusions of less than four weeks following an acute infarction are defined as acute or subacute and occlusions of between four and 12 weeks as recent. Unfortunately, most historical trials, including the Occluded artery trial (OAT), did not adhere to this definition and mostly included subacute and recent occlusions.2,3

According to a recent Canadian registry, CTOs are detected in about 30 % of patients with symptomatic coronary artery diseases (CAD).4 Likewise, a large German monitor-controlled registry found that 27.5 % of 45,722 consecutive patients with CAD had a non-acute total occlusion.5

Benefits of Revascularisation of Chronic Total Occlusion

Similar to stenosed vessels, revascularisation of CTO is indicated in the presence of angina or ischaemia related to the respective territory.6 It has been shown that upon successful reopening, angina will improve, functional tests will be normalised, left ventricular (LV) function will improve and a coronary artery bypass graft (CABG) will be avoided.7–13 However, not all CTOs benefit from revascularisation. A possible survival advantage will mainly stem from improvement in LV function following improvement in the contractility of viable infarcted myocardial segments.14 In support, there are data from a surgical series to show that improved survival in patients with LV dysfunction correlates with the presence of myocardial viability in several LV segments.15 In about 60 % of CTO patients, it appears sufficient simply to prove that no Q-waves are present in the territory of the occluded vessel to achieve recovery of the LV function upon recanalisation.10

Following two recent trials addressing the opening of sub-acute coronary occlusions, there is general confusion regarding the indications for percutaneous coronary intervention (PCI) in chronic occlusions and scepticism about the ultimate impact revascularisation has on patient outcomes.

Do we improve the prognosis? As yet, we do not have the answer. In OAT patients with a recent myocardial infarction (MI) of 3–28 days, the interventional approach showed no advantage in terms of survival and there were more recurrent MIs than with the conservative approach.2 However, as mentioned before, this trial is dealing with a different subset of patients that had infarctions and only poor proof of viability or residual ischaemia. The EuroCTO registry 2008–2010 of 4,820 patients shows that >80 % of the CTO patients had no prior ST-elevation myocardial infarction (STEMI) in the region of the occluded vessel. Randomised trials to show the clinical benefit of recanalisation of long-term occluded arteries are lacking; however, recent reports add evidence to the initial studies of Suero et al. who showed that a successfully revascularised CTO confers a significant ten-year survival advantage compared with failed revascularisation.16

Analysis from the New York State Survey showed that incomplete revascularisation by PCI leaving a CTO untreated led to higher mortality, even during a short follow-up of three years.17 Valenti et al. also showed that a prognostic benefit of complete revascularisation, including opening of a CTO, is likely to be noticed in patients with multivessel disease,18 and a last year’s meta-analysis of 7,288 patients observed over a weighted average follow-up of six years confirms that successful attempts appear to be associated with an improvement in mortality and with a reduction in the need for CABG as compared to failed recanalisation.19 A prospective randomised trial is warranted and will be conducted by the EuroCTO club in 2011.

Why is Chronic Total Occlusion Undertreated?

It is noteworthy that far less than 10 % of percutaneous revascularisations are CTO interventions.4,20,21 Despite a likely benefit for patients with >10 % of viable myocardium related to the CTO artery, most patients are denied revascularisation or sent for CABG.5,6,22 The reasons are manifold, including misunderstandings (‘collaterals are sufficient’), costs, time, and the low success rates of operators not specifically trained in how to open a chronically occluded vessel. Unfortunately most of the earlier reports of CTO results included ‘well-selected cases’ and used a more liberal definition, including recent occlusions, so that the success rates of >60 % 10–20 years ago are unrealistic.12,16,21 Even experienced non-CTO operators, such as the SYNTAX participants, today achieve success rates of only about 50 %, a figure that is similar to the surgeons’ 49 % if their non-attempted revascularisations were included.23 Unfortunately, most centres still do not restrict the recanalisations of CTO to a few selected operators, which results in operators that have insufficient experience (<30/year) performing the recanalisations and poor outcomes. Only high-volume CTO operators will be able to achieve success rates of >80 %.

The clinical presentation of a CTO can be very variable. On the one hand there are patients with stable angina, silent ischaemia or heart failure of ischaemic origin, while on the other hand we see patients with new-onset angina or undergoing primary PCI owing to acute occlusion in a different culprit vessel, and in whom the CTO is discovered as an incidental finding.

As a result of collaterals, patients with a CTO experienced a STEMI in <40 % of the cases and less than half have severe LV dysfunction.24–27 In the EuroCTO registry 2008–2010, only 18 % of the patients present with Q-waves in the territory of the CTO vessel. As shown by Werner et al., in 80 % of the collaterals supplying a chronically occluded artery, the fractional flow reserve is <0.8, which is not sufficient to supply myocardium during exercise.28

Development of Strategies, Techniques and Impact on Results

Although chronic coronary occlusions were being opened as early as 1978 (Martin Kaltenbach, Frankfurt, Germany), it is only during the past 15 years that the recanalisation technique has been refined and specific material developed thanks to a handful of highly talented and dedicated operators, mainly from Japan (Osamu Katoh, Hideo Tamai and Takahiko Suzuki).

The procedural complexity of CTO angioplasty and the lack of familiarity with new equipment and techniques often prompt half-hearted and prematurely aborted attempts at PCI, leading to physician and patient frustration. Consequently, patients with single vessel disease and chronically occluded vessels are often managed medically regardless of the severity of symptoms and extent of ischaemia, and those with multivessel disease with a CTO are referred for bypass graft surgery even if the other lesions are ideally suited for PCI.29,30 Since 2006 the EuroCTO club has been collecting clinical and procedural data of all consecutive CTO procedures (n=11,481), and since 2008 in an online registry (n=4,820) (www.ERCTO.org). Over the past five years the overall success rate has increased from 75 % to 86 % (see Figure 1), reaching 93 % in the hands of the most experienced who enrolled >100 patients annually.

This success rate is superior to that of surgical revascularisation of CTOs.23 Therefore, the presence of a CTO should no longer be a reason to deny percutaneous revascularisation.

Main Steps to Success

The most important prerequisite is operator and team experience in CTO procedures. The operator should be skilfull, trained specifically in CTO intervention, be patient, persistent and yet cautious.

Given that CTO PCI is quite different from PCI of non-CTO-lesions, even years of experience with angioplasty are no substitute for specific experience in recanalisation, which can only be gained through specific training. Whereas the success rate of non-dedicated operators (e.g. the Syntax centres) is in the range of 50–60 %, the EuroCTO-online registry for three consecutive years (2008–2010, n=4,820) reveals that the success rate steeply increases with experience, from 67 % for operators who enrol <35 patients/year to 93 % for those who enrol >100 patients/year. The data also show that it appears to be important to perform at least 30–50 CTO procedures annually to achieve and maintain a success rate of >80 %. It is, therefore, evident that a centre that performs about 1,000 coronary interventions annually, of which about 100 are CTO procedures, should restrict these recanalisations to no more than two operators so that they can maintain a sufficient level of training and keep pace with innovations.

The operator should select patients according to his or her level of expertise and refer those beyond their reach to advanced CTO experts. Today there are no CTOs that should be deemed undoable unless tried twice or three times by a high-level expert, with the exception of chronically occluded vessels with no visible distal target that should not be addressed at all because the ‘blind penetration’ bears an unpredictable risk of perforation and life-threatening tamponade. In general, ad hoc angioplasty is not recommended in the presence of CTOs because they require proper procedures, planning and a ‘stress less’ cathlab window of at least two hours.

A sufficient variety of guiding catheters and wires (including dedicated wires) and the possibility of using multiple balloons and drug-eluting stents (DES) to cover the occluded segment entirely are mandatory.

Patient Preparation

It is mandatory to review the film carefully for best views, occlusion entry and exit and possible mistakes from previous unsuccessful attempts. The patient’s glomerular filtration rate (GFR; ml/min) should be considered as a limit for dye consumption, which should not exceed between four and eight times the nominal number of GFR in ml.31 Given that wire exits are not uncommon during the process of recanalisation, IIb/IIIa inhibitors should be avoided.

Which vessel to address first in stable patients with multivessel disease is still a controversial question. Although more conservative operators claim that the CTO should be tried first and that upon failure the patient should be sent to surgery, others favour attempting the easy severe lesions first, particularly if it is the vessel that donates collaterals, and stage the CTO PCI that later can be addressed more safely – if necessary – also via collaterals. I do not like the widespread philosophy to dilate the culprit lesion and leave the CTO vessel undilated (“the patient was not severely symptomatic since years”) if the latter supplies a relevant amount of viable myocardium.

Access Route and Guiding Catheters

Although a radial approach is feasible, 90 % of experienced operators prefer femoral access, mainly because they are used to it and because this access allows the operator to use larger guiding catheters. Bleeding complications using the femoral approach may be irrelevantly higher than for the radial approach (2.30 % versus 0.05 %) but are still low and similar to that for non CTO-lesions.32 For chronic occlusions a good passive support with coaxial alignment and sufficient lumen to host several wires, an anchor balloon and a microcatheter or Corsair® or even sometimes intravascular ultrasound (IVUS) guidance is crucial. This can only be achieved with larger guiding catheters (7 and 8 Fr). It is noteworthy that 50 % of the procedures carried out by the EuroCTO club are performed with 6 Fr guides. For the left coronary system extra backup-type catheters (Voda left, extra backup, geometric left, left support) are preferable. For the right coronary artery (RCA) we prefer left Amplatz 0.75–2.0 shapes, hockey stick upon gentle superior origin of the RCA, Judkins shape for slightly inferior origin and internal mammary artery (IMA) or shepherd’s crook (SCR)-type guides for upward origin of RCA. For the RCA, I strongly recommend guides with side holes to prevent aortoostial dissections or progressive spiral dissections caused by forceful dye injection into a subintimal space.

In case of ostial dissection, the guiding catheter has to be changed and a soft-tipped wire must be selected and steered carefully past the dissection that needs to be fixed before continuing with the procedure.

It is mandatory to visualise the vessel distal to the occlusion to avoid blind poking or immensely dangerous dilatation of a false wire exit. When the distal vessel is not filled by orthograde collaterals or these collaterals disappear during manipulation, contralateral injection is a must. The contralateral approach can also be achieved by puncturing the same groin with a 4 to 6 Fr catheter, which may ease the procedure. The operators of the EuroCTO Club use contralateral injection in 62 % (range 33–78 %).

Over the wire balloon catheters or microcatheters are used by >80 % of the operators to ease wire manipulation and to allow atraumatic rapid exchange or reshaping of the wires.

Wires

Twenty years ago we opened CTOs with stiff-tipped wires such as the 0.0014 or the 0.0018" ACS Guidant Intermediate® or Standard®, ten years later we switched to improved intermediate and even stiffer wires from Asahi (0.0014 Miracle® 3–12 g), followed by tapered wires such as the Crossit® family (ACS Guidant) or the improved Confianza® family (Asahi). In the past, most operators recommended – and some still do – a so-called step-up technique, starting with, for example, Miracle 3 g, which is then exchanged for a 6 g and eventually a 12 g, which is then followed by the tapered and stiff Confianza wires. The minority started right away with ‘lubricious’ wires, i.e. polymer or polymer-coated of various but generally less tip stiffness, such as the Terumo Crosswire®, Boston Scientific Choice® or PT Graphics® Abbott Whisper®, Pilot® (50, 150, 200) and more recently the Asahi Fielder® and the tapered Fielder XT®. Although these polymer wires might grant rapid success in 28 %,27 those with a stiffer tip may easily slip beneath plaque and create a long false channel without discernible friction, mimicking a correct lumen, and convince the operator to dilate and stent it.

In our EuroCTO registry, the Miracle 3 g was the wire used in 32 % of successful procedures in 2008 but was only used in 17 % of successful procedures in 2010.27 The most popular current strategy is to start with the very atraumatic tapered and highly lubricious Fielder XT®, which according to the EuroCTO registry, is successful in 39 % of procedures. The second most popular selection – especially in old and calcified occlusions that are not very tortuous is to select stiffer tapered wires, such as the Confianza 9 Pro® early in the process to minimise the risk of large dissection as well as shorten and simplify the procedure. Another recent line of action is to start with a soft tapered polymer wire (e.g. Fielder XT), to quite rapidly step up (Confianza 9 Pro or Miracle 6 g) and then step down to a softer wire again. The Confianza 9 Pro has been the successful wire in 22–25% of the EuroCTO club's procedures for the past three years. Optimal shaping of the wire tip is essential for its successful crossing. In general, a small distal curve of approximately 1.0–1.5 mm of 30–45 degrees (primary curve) is needed to penetrate the occlusion entry or to exit the distal cap. My approach towards wires is to start with a Fielder XT if the stump is tapered and the CTO is not very old and not heavily calcified, to use a Miracle 3–12 for moderate tortuous very old occlusions, a hard-tipped polymer wire such as Pilot 150 for tortuous old occlusions with a blunt stump and Confianza 9 Pro for less tortuous occlusions appearing quite difficult to deal with (calcified, stump not tapered, very long). Soft polymer wires such as Whisper LS®, Fielder FC® are used for retrograde wiring and may later be exchanged for stiffer wires.

Wiring Techniques

There is no easy way to get a wire to the distal end of the CTO. It requires trial and error and learning from the mistakes of the past. Calcification or occluded stents are often a good guide to the vessel course. However, even if the calcification appears straight, one should proceed with caution because there is no guarantee that the channel will be straight as well.

The three fundamental elements of wire handling are rotating, pushing and pulling the wire. It is important to feel the resistance at the wire tip when pulling the wire because a wrong channel often exerts a much higher resistance than the correct lumen. Rotating the wire is important because it enables you to minimize the resistance at the tip as the wire advances, and it also makes it easier to achieve the penetration at the distal cap. If resistance is felt during advancing, pushing strongly (e.g. by advancing the over-the-wire [OTW] catheter to within less than 10 mm of the tip of the wire to increase stiffness and push ability) may open a false lumen. Any wire has the tendency to follow the outer part of the vessel curve, which can often cause the tip to exit the lumen. It is therefore preferable to direct the wire-curve towards the inner part of the vessel bend.

Parallel-wire Technique

I first described the parallel-wire technique in 1995 and it was then further developed by Osamu Katoh (Reifart N, The parallel wire technique for chronic total occlusions, Interventional Course, Frankfurt, 1995: personal communication). It is the best technique to correct a false wire position. If, for example, the first wire has entered a false lumen, it is left in place to mark the dissection channel, and a second wire (typically of the same stiffness or stiffer and often tapered) with a slightly different tip curve to allow the creation of a slightly different course supported by an OTW (balloon) catheter, is passed along the same path parallel to the first wire, with care taken to avoid wire twisting. This technique allows for penetration towards the distal cap more centrally, avoiding the false channel, which is marked by the wire left in situ. If the second wire also fails to enter the distal lumen and instead enters a second subendothelial track, often on the opposite wall, the first wire is withdrawn and steered in the direction of the true lumen (the socalled ‘see-saw’ technique). Occasionally, three or more wires are used. It cannot be emphasised enough how essential it is to be certain that the wire position is correct, especially beyond the distal re-entry. This requires a contralateral injection in all cases without ipsilateral filling. Even if the wire can be advanced easily distal to the occlusion along the expected vessel path, a balloon should not be advanced before the intraluminal wire position is confirmed in two orthogonal views by contrast filling the distal bed via collaterals. Although some operators advocate intentional large antegrade dissections with polymer wires, hoping for a lucky subintimal tracking and re-entry (STAR technique)33 or with superselective injections into the false channel,34 the technique is not advisable in general because re-entry is not guaranteed and side branches might get lost because contrast may expand the false lumen, staying there for a prolonged period and making it difficult to enter the compressed true lumen. Nevertheless some operators use this rather rude track as a last resort if all other more skilful techniques have failed.

Side Branch Technique

CTOs with a tapered stump are easier to deal with than those with a blunt stump. No stump at takeoff of a side branch is even worse and often requires identification of the entry by means of IVUS at the side branch. However, entering the occlusion may still be impossible. Before switching to a retrograde approach you may try to break the proximal cap with a balloon inflated in the main vessel and side branch across the take-off. This technique may successfully open the entry in 30–40 % with a risk of subintimal dissection requiring re-entry with a tapered stiff wire.

Prywire Technique (Open Sesame)

A similar situation can sometimes be solved easily with a wire left in the side branch at take-off. The wire may not only serve as a marker for the take-off but also sometimes lever the side branch and enlarge the bifurcation angle and thus unmask a tiny stump.35

Re-entry Technique

It is difficult to distinguish reliably between the intraluminal and the subintimal course of the wire and we often experience wire exit and re-entry without knowing. Hence deliberate re-entry instead of searching for the correct proximal entry is a manipulation that is often successful. It appears more reliable with stiff and tapered wires scratching and puncturing the intima towards the inner lumen; however, for the sake of time many operators prefer to use tip-deflected polymer wires and a STAR-like technique with the risk of longer dissections and shearing off collaterals and side branches. Recently, we described a new device comprising a flat balloon catheter with a distal side hole for a puncturing wire to the exit. Upon balloon inflation the side hole is automatically directed towards the inner lumen to facilitate re-entry with the needle-like tip of the puncturing wire.36

Microcatheters, Balloons, Techniques to Deal with Balloon Failure

Most operators start the procedure with a microcatheter (e.g. Terumo Finecross®, Cordis Transit®) or a 1.25 mm OTW balloon (e.g. Medtronic Sprinter®, Terumo Tazuna® and Boston Scientific Apex®). If the balloon with the best crossing characteristic (not necessarily the one with the lowest profile) is unable to follow the wire past the occlusion the following techniques are helpful and should solve the problem in >90 % of cases:

  1. Insert a second wire with a stiff shaft (Abbott Extrasupport® or Ironman®) proximal to the occlusion, preferably into a side branch to increase guiding support (wire anchor technique).37
  2. Inflate a 2 mm balloon at the side branch for further support (balloon anchor technique).37
  3. Exchange the balloon or microcatheter for a Tornus® or Corsair38,39 to enlarge the channel. This technique should succeed in 90 % of balloon failures.40

It is important to ensure a stable wire position while pulling or exchanging the OTW catheter for a Tornus or Corsair. The simplest approach is the flushing technique where the wire–channel is flushed with high pressure (manually or with the inflation device). The reduced friction between wire and lumen in most cases allows the catheter to be pulled without the wire. A safer option is to inflate a 2.5 mm balloon in the guiding catheter parallel and distal to the OTW to trap the wire (balloon trapping). Leaving the balloon inflated will allow the Tornus or Corsair to then be safely advanced. According to the EuroCTO registry in 2010, the Tornus was used in 5 % of the procedures (reflecting balloon failure as main indication) and the Corsair in 13 % (mainly as a retrograde channel dilator).

Complementary Imaging

IVUS and multislice computed tomography (MSCT) were used by the members of the EuroCTO club in only 1.5 % (IVUS) and 4 % (MSCT) of 1,977 CTO procedures in 2010. This is probably mainly because of budget restrictions and is in contrast to Japan and the US where ancillary imaging techniques, particularly IVUS play a much larger role. IVUS appears helpful to identify the take-off of the occluded vessel when no stump is discernable, to facilitate re-entry after having created a large false channel and to identify the position of the retrograde wire in the dissection channel as well as to measure the vessel diameter and safely select the proper balloon size. MSCT might be useful to depict a long tortuous occlusion segment and the location of calcifications not visible angiographically – which is helpful information if the first attempt to recanalise has failed.

Predictors of Failure (Antegrade Approach)

It is advisable to stop the recanalisation for one of the following reasons: excessive dye consumption (e.g. more than eight times the GFR in ml), exposure for more than four hours, excessive radiation exposure,41,42 long dissection shearing off collaterals and inability to visualise the vessel distal to the occlusion. If there is a strong indication for revascularisation, a second attempt either antegrade or retrograde is strongly recommended. The EuroCTO registry data nicely substantiate that it is worth scheduling the patient again. The success rate of a second attempt is 85 % if a different operator had failed before (n=636) and 69 % if it was the same operator who failed before (n=260).

The main reason for failure is inability to cross the occlusion with a wire whereas failure to properly deliver a stent, slow flow or no flow due to embolisation or failure to follow with a balloon has become rare. A blunt stump, a CTO length >20 mm and the presence of severe calcification were recognized as univariate predictors of procedural failure (odds ratio [OR] 12.4, 95 % confidence interval [CI] 0.49–0.816, p<0.001, OR 20.9, 95 % CI 0,301–0.619 p<0.001 and OR 17.1, 95 % CI 0.348–0.686, p<0.001, respectively). After multivariate analysis the same variables resulted and were recognised as independent predictors of procedural antegrade failure (OR 11, 95 % CI 0.435–0.807, p=0.001, OR 9.6, 95 % CI 0.352–0.79, p=0.002 and OR 29.2, 95 % CI 0,241–0.515, p<0.001, respectively).43

Retrograde Approach

If a vigorous antegrade attempt to open the vessel has failed, a second attempt – antegradely or retrogradely – is promising in most patients. The first report of retrograde recanalisation of a CTO was published by a French group in 1996.44 In 2005, Katoh and colleagues opened an important new window, pioneering the modern era of retrograde CTO recanalisation with the ‘Controlled Antegrade and Retrograde subintimal Tracking’ (CART) technique.45 The novelties introduced in this procedure were the targeted septal collateral crossing and the connection of an antegrade and retrograde subintimal channel.

To facilitate this approach several tools were newly developed, such as the channel dilator Corsair, a long wire for externalisation (Asahi RG3®). Short (90–95 cm) or shortened guiding catheters (GCs) are sometimes necessary, particularly in long epicardial connections. Monitoring anticoagulation during the procedure is important. An activated clotting time should be measured every 30 minutes and should be maintained over 300 seconds until the end of the procedure is foreseeable to avoid any thrombotic complications in the donor artery, which are potentially lethal.

Crossing the Collaterals

Septal collaterals are used most often (about 75 %) followed by epicardial collaterals, which are in general larger but more tortuous and more difficult to traverse. Stronger and straight collaterals are easier to cross than invisible and tortuous connections; however, it is not uncommon to discover that the collateral that appeared less favourable was quite easy to cross.

There are three main techniques that are used to cross and dilate the occlusion:

  • Retrograde marker wire at the distal end of the occlusion as a target for the antegrade stiff and tapered wire.
  • Retrograde penetration of the occlusion with wire and Corsair and externalisation of a long wire such as a Rotablator wire or an Asahi RG3 via guiding catheter exiting the 'antegrade sheath' followed by antegrade stenting.
  • Connecting both false wire channels either via retrograde subintimal dilation (CART-technique) or antegrade subintimal dilation/reversed CART-technique) followed by antegrade stenting.

Indication and Results of Retrograde Approach

Given that the retrograde approach is generally more difficult and time consuming all CTO procedures should be started in an antegrade way with few exceptions. This is confirmed by the attitude of the EuroCTO club where the percentage of retrograde intervention was stable at about 10 % per year between 2008 and 2010. The more complex nature is again documented by the EuroCTO club registry 2008–2010: the procedural time of the antegrade approach was 87 minutes and dye consumption was 268 ml in 4,299 patients versus 154 minutes and 383 ml dye consumption in 501 patients with the retrograde approach. The success rate in 2010 reflecting the most recent techniques was 86 % for all procedures, 87 % in antegrades and 79 % in retrogrades. To make matters worse the retrograde approach is handicapped by a two- to threefold higher incidence rate of severe in-hospital complications.

The most difficult part is the successful transition of collaterals, which might only be possible in 60–70 % of CTO patients and is not even worth trying in those with very tortuous collaterals or none at all. In summary, the retrograde approach is a valuable strategy for failed antegrade attempts, but less successful and less safe and by no means a substitute for poor antegrade skills or a stage for ‘interventional artists’ to demonstrate that a procedure that is suitable for an antegrade approach can also be performed retrogradely.

Complications

In-hospital complications are rare but not negligible: quite similar to PCI of non-occluded vessels in the EuroCTO online registry 2008–2010 (n=4,820 patients), death occurred in 0.3 %, any MI in 2.7 %, and emergency CABG were performed in 0.21 % and cardiac tamponade in 0.45 %.

There is a higher risk of perforations (1–5 %), contrast-induced nephropathy (0.5–1.0 %) and, albeit rarely, radiation injury.46 As mentioned earlier, the complication rate with the retrograde approach exceeds that of the antegrade approach by at least two to three times (major adverse cardiac events 4.5 %)47 and, according to Werner, infarctions defined as a creatine kinase rise of more than three times the upper limit were 3.1 % following the antegrade approach and 7.1–20.0 % following the retrograde approach via septal or epicardial collaterals.48 Some of the complications of the retrograde approach are quite unusual, such as collateral perforation, septum haematoma, aortic dissection, dissection and thrombotic occlusion of the collateral donating vessel or severe wire entrapment. Unfortunately many operators are encouraged to try this impressive approach after having witnessed a few cases in live courses but their results and complications do not get reported.

Long-term Results in the Drug-eluting Stent Era

Until recently, opening CTOs was not only unpopular because of a dramatically lower success rate but also because of a hard to take higher restenosis rate of up to 50 % and a reocclusion rate of up to 20 % with bare metal stents.49 Fortunately, several non-randomised and two randomised trials have clearly documented a >50 % reduction in restenosis and reocclusion with DES (Suttorp MJ, Prison trial 3 y outcome, 2008, personal communication).49,50 Among these the newer DES generation may be even more favourable.51

Although there is no scientific proof, dual antiplatelet medication is generally recommended for 12 months and may probably be safely reduced to six months with DES that have a bioabsorbable coating.50

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