Example of usefulness of viability testing to guide decision making in CTO. A 65-year-old male with two episodes of acute pulmonary oedema underwent coronary angiography demonstrating occlusion of distal right coronary artery (red arrow). An echocardiogram revealed that the inferior wall was akinetic (yellow arrow). Myocardial SPECT demonstrated preserved resting perfusion indicative of myocardial viability in the inferior wall with additional exercise-induced ischaemia. The patient underwent a successful CTO procedure to reopen the right coronary artery. A followup echocardiogram performed 7 months post CTO showed improved contractility in the inferior wall. See also Supplementary data online, Movie S8. CTO, chronic total occlusion; SPECT, single photon emission computed tomography.