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CTO, A Challenge Not Only for PCI, But Also for EP

We read with great interest the paper by Di Marco et al.1 in the Journal of Cardiovascular Electrophysiology. Chronic total occlusion (CTO) has been paid much attention as to percutaneous coronary intervention (PCI) procedures, for its challenging technology and debates on related assessments.2 In the present study, the authors reported a significant higher recurrence after ventricular tachycardia (VT) ablations in patients with CTO in infarct-related artery (IRA), which implies that IRA-CTO also indicates a more challenging procedure for electrophysiologists. However, we hold the following opinions on this study: As is well known, the pathology of infarction or scar areas is related to the local potentials and arrhythmia. Hence, the assessment of reversible ischemia in the CTO-related area should be essential not only for the strategy selection in PCI procedures but also for electrophysiology procedures. Although, as the authors mentioned, no systemic data on evaluation of reversible ischemia or viability are available in this study, the presence or absence of electrocardiographic Q waves in CTO-related leads may provide an alternate method for this based on a previous study,3 which implied that reversible ischemia can be predicted by the absence of Q wave in CTO-referred areas. As Q waves are only mentioned as part of the inclusion criteria and are not analyzed linking to IRA-related areas in this study, we are wondering whether the absence of Q waves related to IRA-CTO or scars can influence the results of ablations, which hopefully provide us a new predictor of successful procedures. Furthermore, with regard to the ablation strategy used in the study, late potential (LP) abolition is reported by the same group to be a useful combined end point that can predict less recurrent VTs than achieving noninducibility only.4