The retrograde technique for recanalization of chronically occluded coronary arteries: Case series report

Background. Chronic total occlusion (CTO) of coronary artery still represents
 one of the most challenging lesion subset in field of interventional
 cardiology. Considering the complexity and increased risk posed by the
 retrograde approach, it is most often performed after a failed antegrade
 approach. Methods. We present a series of cases dedicated to the retrograde
 approach as a special technique for the treatment of chronic total coronary
 artery occlusion. All cases have some special characteristics that are today
 part of a dedicated portfolio in every cath lab. Results. In our series of
 cases all of three percutaneous coronary interventions (PCI) with retrograde
 approach finished with successful recanalization of CTO with different
 strategy and supported with rotational atherectomy (RA) or intravascular
 ultrasound (IVUS). Conclusion. In cases where there is the presence of
 interventional collaterals, as well as when the anterograde approach is very
 difficult, the retrograde approach can increase the success rate of
 procedures. The retrograde approach requires a long learning curve as well
 as very skilled and experienced operators who are able to perform the
 procedure independently.

along with the growing experience of operators (1,2). Many retrospective and prospective registries show better survival, improved left ventricular function, reduced risk of malignant arrhythmias as well as CABG in procedural success groups (3,4). Recent randomized clinical studies suggest a better quality of life in patients with successful recanalization of an occluded blood vessel compared to patients on optimal drug therapy (OMT) (5)(6)(7)(8). Among the various techniques for PCI CTO, the retrograde approach with different strategy types is considered the most complex. The retrograde approach should be considered in occlusions with "interventional" collaterals (i.e., collaterals deemed to be negotiable by the operator depending on his/her experience), diseased landing zone, bifurcation at distal cap, and/or proximal cap ambiguity (9,10). Therefore, the aim of this case series is to present a complex retrograde technique as the first strategy choice according to the indication in every single case, combined with contemporary armamentarium of available devices (guiding catheter extension, rotablator od intravascular imaging) to achieve a succesfull and optimal result. All cases were performed at the Cardiology department of the Clinical Center of Serbia.

Case 1.
A 69 year old male had a posterior myocardial infarction in April 2019 as the first manifestation of coronary heart disease. He generally complains of typical anginal symptoms with minimal physical exertion. SEHO test wasn"t done. Echocardiographic examination showed a left ventricle of normal dimensions with hipokinetic inferolateral wall and preserved systolic function, EF 50%. Apart from hypertension and a positive family history of CVD, he had no other risk factors.

#1
During index hospitalization, primary PCI have been attempted, in which a singlevessel coronary disease, a calcified subocclusive lesion about 20 mm long in the proximal segment of the dominant Cx artery, intermediate stenosis in the medial segment of the LAD and minor RCA were observed. Furthermore, through the right radial approach a catheter guide EBU 3.5 / 6F was placed in the LM shaft. After a challenging placement of the Sion blue (Asahi Intec Co., Japan) coronary wire in the distal segment of the Circumflex (Cx) artery, a 2.5x20 mm semi-compliant balloon was placed at the lesion site after being supported by a GuideZilla 6F extension catheter (Boston Scientific, Marlborough, MA).
Due to the inadequate expansion of the semi-compliant balloon, an attempt was made to place the non-compliant (NC) balloon, without any success (figure 1).

#2
In May of the same year, PCI of the same lesion was attempted by the femoral approach 6F. The same catheter guide and coronary wire were placed, after which a 3x20 NC balloon predilatation was performed. A larger dissection was formed and the stent could not be placed due to the deviating angle and the existing extensive calcifications (figure 2). It is proposed to present the patients to the Heart Team, which met in June at the CCS. The council made the decision to do the first FFR for the lesion on the LAD and if the lesion is functionally significant, the patient will be offered surgical revascularization of the myocardium. Otherwise, it is suggested to try PCI Cx again using a rotablator.

#3
In the same month, the EBU 3.5 / 7F guide catheter was placed by right radial access and the flow reserve was measured at 0.84. With the support of the Corsair microcatheter (Asahi Intec Co., Japan), Gaia 2 (Asahi Intec Co., Japan) has currently not undergone occlusion in the proximal Cx segment with developed ipsilateral collaterals (CC 1-2). Further intervention was abandoned (figure 3).

#4
A month later, in July 2020, a femoral approach with an EBU 3.5 / 7F guide catheter was set up for a fourth PCI attempt at the same center. After the placement of the temporary PM, the coronary arteries of BMW (Abbott Vascular) as well as Fielder XT (Asahi Intec Co., Japan) did not undergo occlusion and further intervention was abandoned (figure 4).
It was concluded that the fifth attempt would be in a dedicated center. The fourth attempt to recanalize the CTO RCA started with a bifemoral approach.
Angiographically, single-vessel coronary heart disease has been previously verified, with occlusion more than 5 cm long from the RCA ostium. The posterolateral branch did not show from retrograde collaterals and the impression was gained that it was occluded from its ostial segment ( figure 11). The Corsair microcatheter was placed practically to the distal occlusion cap via LCA intervention collaterals, after which Sion black was replaced with Gaia 3 coronary wire. Subsequently, a reverse CART technique was performed with the help of the Guidezilla extension catheter (figure 12). Gaia 3 retrograde wire was placed in an anterograde extension catheter. Following, externalization was performed with RG3 (Asahi Intec Co., Japan) and 3 drug-eluting stents were placed after appropriate predilation.
Due to the lack of adequate flow in the distal segment of the artery, intravascular ultrasound (IVUS) optimization was performed, followed by additional angioplasty. TIMI 3 coronary flow was obtained (figure 13).

Case 3.
A In-stent CTOs represent about 12% of all PCI CTOs and these procedures are more complex than in unstented blood vessels (14). In the third case proximal cap of the occlusion was ambiguous with a small brunch originating at that exact level. The occlusion was positioned at least 10 mm proximally to the proximal edge of the previously implanted stent. In such a cases antegrade approach is possible with IVUS guided antegrade puncture (with IVUS probe in the side brunch if possible) or by the analyses of the index procedure and possibly available CT angiography. In this case, the operator correctly started with retrograde approach using septal interventional collateral which allowed very easy crossing of the occlusion body with standard Gaia second wire (Asahi Intec Co., Japan) due to the fact that distal cap is usually softer than proximal one and that proximal vessel was a relatively big target.
We would like to underline that the first retrograde procedure was performed in 2009 by prof. George Sianos from Greece as a guest operator in Belgrade, and during the same year prof. Sinisa Stojkovic did the first retrograde recanalization of right coronary artery in Clinical center of Serbia. Since than until present time we have estimated that roughly 300 procedures performed with retrograde approach in Serbia (15).
In conclusion, the retrograde approach should not be used as the first choice technique and is usually reserved for situations after an unsuccessful attempt to recanalize using the antegrade approach. In certain cases, as shown in our series of cases, the retrograde technique can be used as the first choice especially in cases where "interventional" collaterals are observed and when anterograde recanalization seems challenging due to the complex coronary anatomy of the occluded coronary vessel (16).