Quality of Life Assessment in Patients With Coronary Artery Chronic Total Occlusion: Randomized Comparison of Optimal Medical Therapy and Percutaneous Coronary Intervention

Coronary artery chronic total occlusion (CTO) is defined as complete occlusion of coronary arteries that lasts for more than three months (TIMI 0 coronary flow in occluded segment). In absence of serial angiograms , occlusion duration can be assumed based on clinical data regarding event that caused occlusion. Consensus document from the Euro CTO club suggests 3 levels of certainty:

a) Certain (angiographically confirmed): the minority of cases where a previous angiogram (for instance before a previous CABG operation, or after an acute myocardial infarction) has confirmed the presence of TIMI 0 flow for > 3 months prior to the planned procedure; b) Likely (clinically confirmed): objective evidence of an acute myocardial infarction in the territory of the occluded artery without other possible culprit arteries >3 months before the current angiogram; c) Possible (undetermined): a CTO with TIMI 0 flow and angiographic anatomy suggestive of long-standing occlusion (collateral development, no contrast staining) with stable angina symptoms unchanged in the last 3 months or evidence of silent ischemia; in case of recent acute ischemic episodes (acute myocardial infarction or unstable angina or worsening effort angina), a culprit artery other than the occluded vessel should be present.

CTO is an often finding. In spite of that, there is uncertainty should this lesions be revascularized and in what way. If there are symptoms or objective proof of ischemia and viability in the area of occluded artery distribution, recanalization of CTO should be considered. Several studies showed that in the presence of chronic total occlusion collateral circulation may produce supply of oxygen and preserve viability. However assessment of collateral circulation with adenosine stress test showed abnormal coronary reserve in over than 90% was reduced which means that collaterals are not enough Therapeutically uncertainties lead partially from technical complex procedures of revascularization CTO with PCI, with success rate of 60-70% which is importantly lower than revascularization rate of non-CTO lesions (98%). During last decade there has been significant improvement in technology, equipment and techniques of percutaneous revascularization procedures for CTO that increased procedural success rate (around 90%). On the other hand there are separate views regarding possibility of treating this patients with coronary artery bypass graft (CABG), and specially patients with single coronary disease Metaanalysis performed by O'Connor SA et al. showed that presence of chronic total occlusion on non infarct artery in patients with acute myocardial infarction significantly increases mortality. Furthermore several mataanalyses that analyzed the effect of PCI CTO on survival, showed significant reduction of mortality rate in short term and also long term follow up. Studies enrolled in this metaanalyses were retrospective or prospective registries which compared successful PCI CTO with PCI CTO failure.

There are different explanations for this clinical result (mortality reduction):

1. direct benefit of achieving coronary flow and myocardial perfusion improves ventricular function and reduces risk of malignant arrhythmias
2. patients in which PCI was unsuccessful probably have more serious coronary atherosclerosis and fibrosis that contribute to procedural failure and greater mortality (3).