‘Small bifurcation?’ CT myocardial mass volume measurements change therapeutic strategy in coronary artery disease Youssef S. Abdelwahed 1,2,3, Anne-Sophie Schatz1,2,3, Ulf Landmesser 1,2,3, and Carsten Skurk1,2** 1 Department of Cardiology, Charité—Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, Berlin 12203, Germany; 2 DZHK (German Centre for Cardiovascular Research), partner site Berlin, Potsdamer Straße 58, 10785 Berlin, Germany; and 3 Berlin Institute of Health (BIH), Anna-Louisa-Karsch-Straße 2, 10178 Berlin, Germany *Corresponding author. Tel: +49 (0)30 450 513702, Email: [email protected] A 54-year-old male complaining of recurrent chest pain on exertion (CCS 2) was electively admitted for a second recanalization attempt of a chronic totally occluded (CTO) first diagonal branch. Two years ago, a drug-eluting stent (DES) deployed to the proximal LAD jailed the diagonal ostium leading to its occlusion. Based on the angiographic analysis, seen by contrast filling through the epicardial retrograde collateral flow from the distal LAD, the vessel was considered to be of small calibre (Panel 1A). Because of the perceived interventional risk, intensified maximum medical treatment was the therapeutic strategy of choice. However, the patient was still suffering from recurrent chest pain. To gain more insight on the importance of the diagonal branch regarding the myocardial mass at risk (MMAR) and its anatomy, a pre-procedural cardiac multi-detector computed tomography (MDCT) scan was performed (Panel 1B). Surprisingly, the MDCT revealed an MMAR of 23.9% supplied by the diagonal (Panels 2A and 2B). Therefore, the strategy changed aiming for a new recanalization attempt. After a brisk unsuccessful antegrade trial, we switched to retrograde approach. The channel was safely crossed (Panel 3A) followed by successful PCI after externalization of the retrograde wire (Panel 3B). Patient’s symptoms immediately subsided following the intervention. Whether to recanalize an angiographically estimated small side branch or not often represents a challenge for PCI operators. This case illustrates that MDCT can safely determine the MMAR, hence, contributing with important information for therapeutic decision making, besides adding data on CTO length, vessel anatomy, calcium, and viewing angles. (Panel 1A) Pre-recanalization angiography indicating a DES in the proximal LAD occluding the first diagonal (green arrow). Retrograde filling of the branch is provided by epicardial collaterals from the distal LAD. (Panel 1B) MDCT image showing the proximal stent ending just few millimetres distal to the diagonal bifurcation (Fujifilm Synapse 3D). Some mild calcium is depicted in the diagonal (white arrow). (Panel 2A and 2B) Multi-3D VR image of MDCT illustrating the MMAR supplied by the diagonal. The area comprises 23.9% of the myocardium. (Panel 3A) Safe retrograde collateral crossing, with subsequent crossing of the jailed occluded segment. (Panel 3B) Final angiography after successful recanalization of the diagonal branch. Data availability: The data underlying this article are available in the article and in its online supplementary material. Funding: the authors report no specific funding related to this article. Conflict of interest: The authors have submitted their declaration which can be found in the article Supplementary Material online.