Following unsuccessful CTO crossing a CTO modification procedure is sometimes performed. CTO PCI registries where plaque modification has been performed in some patients, report this to be safe, and associated with higher success rates at subsequent attempts. It has never been investigated whether a planned investment procedure, with an intention that both the initial and staged completion PCI are of shorter duration, could improve safety and efficacy. The investigators hypothesize that 1. A planned investment procedure in the treatment of CTOs will be associated with improved patient safety 2. A planned investment procedure will be associated with improved cumulative procedure success rates 3. A planned two stage procedure will be associated with improved patient experience