Coronary chronic total occlusions (CTOs) are among the most challenging coronary artery lesions to treat percutaneously. In the last decade, great strides have been made to develop techniques to improve success rates. While success rates among high-volume operators are >90 %, non-CTO operators still continue to struggle with this lesion subset. Thus, efforts have been made to develop algorithms to help operators achieve successful recanalisation consistently and improve patient outcomes. The North American Total Occlusion (NATO) algorithm emphasises dual coronary injection using two guide catheters, which allows for switching from an antegrade to retrograde approach or vice versa should the initial strategy fail - the so-called 'hybrid' approach. Special attention is paid to four angiographic characteristics: 1) location of the proximal cap, 2) lesion length, 3) presence and suitability of collateral vessels for retrograde crossing and 4) location and quality of target vessel distal cap. The ultimate goal of this algorithm is to provide a strategy to achieve successful CTO revascularisation while using the least amount of fluoroscopy, contrast and equipment possible.
Keywords: Percutaneous coronary intervention; coronary chronic total occlusion.