Definition and Prevalence
Chronic coronary occlusions (CTOs) are defined as lesions with Thrombolysis in Myocardial Infarction (TIMI) 0 flow older than three months (either angiographically proven or with high clinical likelihood). 1 According to a recent Canadian registry, CTOs are detected in about 30 % of patients with symptomatic coronary artery diseases (CAD).2 Likewise a very large German monitor controlled registry found that 27.5 % of 45,722 consecutive patients with CAD had a non-acute total occlusion.3
Indication of Chronic Coronary Occlusion Percutaneous Coronary Intervention
The overriding principle in medicine is to improve symptoms and/or prognosis. Thus revascularisation of CTO is indicated only in the presence of angina or ischaemia related to the respective territory. 4 It has been shown that upon successful reopening angina will improve, functional tests will be normalised, left ventricular (LV) function will improve and coronary artery bypass graft (CABG) will be avoided.5-10,11 Improved LV dysfunction correlates with the presence of myocardial viability in the respective LV segments,12 and it has been shown to attain better prognosis. In about 60 % of CTO patients it appears sufficient to simply prove that no Q-waves are present in the territory of the occluded vessel in order to achieve recovery of the LV function upon recanalisation. 8 The EuroCTO registry 2008-2010 of 4,820 patients clearly elucidates that more than 80 % of the CTO patients had no prior ST-elevation myocardial infarction (STEMI) in the region of the occluded vessel, and we might deduct a prognostic impact of successful CTO percutaneous coronary intervention (PCI) in these patients. Frankly, we do not yet know if we are improving life-expectancy. In the Occluded Artery Trial (OAT) patients with a recent myocardial infarction (MI) of 3-28 days there was no advantage of the interventional approach in terms of survival and there were more recurrent MIs than with the conservative approach.13 However, this trial is dealing with a different subset of patients that had infarctions and only poor proof of viability or residual ischaemia. A meta-analysis of 7,288 patients observed over a weighted average follow-up of six years confirms that successful attempts appear to be associated with an improvement in mortality and with a reduction for the need for CABG as compared with failed recanalisation.14 In summary, patients who are symptomatic or ischaemic despite optimal medical therapy as well as those with relevant viable territory (>5 % of myocardium) should deserve revascularisation.