One or Two CTOs? 

A 59 male presented with exertional chest pain. He had a background of diabetes mellitus, hypertension and hyperlipidaemia. Treadmill exercise test was positive for ischaemia. His left coronary angiogram showed his LAD terminated at the proximal anterior interventricular groove resembling a mid-LAD chronic total occlusion (CTO).  Distal left main (LM), mid left circumflex (LCx) and prox LAD have 50%, 80% and 80% stenosis respectively (Figure 1). Mid to distal right coronary artery (RCA) was blocked with 90% stenosis at prox RCA and no collaterals supplying the distal LAD (Figure 2). A third coronary artery was identified originating from the anterior right coronary cusp. It ran an intramyocardial course at the septum and gave off septal perforators which form collaterals to posterior descending artery (PDA). It then entered the anterior interventricular groove (AIVG) below the termination point of the LAD from the LM and terminated at the apex (Figure 3,Figure 4).  The coronary angiogram was consistent with the diagnosis of a variant form of type VII dual LAD.  Patient refused coronary artery bypass grafting and preferred percutaneous coronary intervention.

The LM/LAD and LCx bifurcation lesions were treated with culotte stenting (Figure 5). RCA CTO was attempted by retrograde approach. The anomalous long LAD was engaged with 7F AL1 SH 90cm guide. Septal channel was successfully crossed with Sion GW supported by Corsair microcatheter.  Distal wiring crossing from septal to PDA was very difficult because of the apically directed channel. The wire ended up in a false channel far from the true RCA (Movie 1). Next antegrade approach was attempted.  With the support of Corsair, same Gaia second was used to puncture the proximal cap and advanced into the CTO body. However despite changing the GW to Conquest Pro 12 / Fielder XTA GW followed by knuckle wire technique (Figure 6), advancing GW across the CTO body was extremely difficult. 1cc contrast was then injected through Corsair microcatheter to expand the subintimal space (Carlino technique) (Movie 2). Conquest Pro 12 was then able to reach the posterolateral ventricular branch through the subintimal space created.  However GW reentry into true lumen was unsuccessful (Figure 7).  Retrograde approach from LCx epicardial channel was then tried.  LM was engaged with 7F EBU 3.5 guide. LCx was wired with Sion GW into epicardial collateral.  After opening up the LCx stent cell strut with a 1.25/15mm balloon, Sion GW supported by 150cm Caravel microcatheter successfully crossed the epicardial channel and reached the distal cap (Movie 3). Gaia 2nd GW was advanced into CTO body. Reverse CART was performed by inflating a 2.0/15mm balloon from the antegrade guide at distal RCA. Both GWs were confirmed to be in same lumen by IVUS (Figure 8). However to advance the retrograde wire along the same lumen with the antegrade wire was difficult.  A 6F Guideliner was inserted from the antegrade guide. It could only reach the proximal cap of CTO. A 2.5/15mm balloon was inserted from the antegrade guide to dilate the CTO body and inflated at the distal RCA where both GWs overlapped. With the support of this anchoring balloon, both Guideliner and Caravel could be advanced further. Finally after further dilated with CTO body with 3.0/15mmNC balloon, direct retrograde GW crossing into Guideliner was achieved with Conquest Pro 12 (Figure 9). The retrograde GW was then trapped with 2.5/15mm balloon at the antegrade guide and the Caravel was advanced into the antegrade guide.  Next the Retrograde GW was exchanged for a 300cmPT2 GW for externalization. GW position was confirmed with IVUS. The whole vessel was then stented with 2.0/30 mm, 2.75/38mm, 3.5/38 mm and 4.0/18 mm DES after balloon dilatation. Final angiogram showed good RCA flow (Movie 4).

 This case illustrates that CTO intervention in patients with congenital coronary anomaly can be challenging. Firstly there may be a diagnostic challenge. Certain types of dual LAD system mimic LAD CTO. The presence of a CTO in another vessel may confuse the picture. Secondly because of the rarity of this condition, most data regarding these patients are only limited to case reports or case series. There is a lack of evidence on how these patients should be optimally treated. Lastly since most people do not have much exposure to this condition, interventionist may need to tackle lesions with different strategies because of the unusual anatomy.