The association of myocardial injury during chronic total occlusion percutaneous coronary intervention with lesion complexity and treatment strategy
Authors: Oksnes A , McEntegart M 
Published: October 2021

Abstract

Background
Chronic total occlusion (CTO) percutaneous coronary intervention (PCI) is associated with procedural myocardial injury (PMI), and adverse long-term clinical outcomes [1–4].CTO lesion complexity is quantified using established scores [5–8], with high complexity known to determine the need for dissection and re-entry techniques and the retrograde approach, which are then associated with a higher incidence of procedural complications [9,10]. If CTO recanalization is unsuccessful, a modification procedure can be performed, with the intention to improve subsequent procedural success [11–14]. There are limited data on the association between PMI, CTO complexity and treatment strategy.

Purpose
To report the incidence of myocardial injury following CTO PCI, and assess whether this is associated with lesion complexity, crossing strategy, or the use of a modification procedure.

Methods
This is a retrospective analysis of consecutive elective CTO PCI procedures performed at a single centre in Norway between January 2020 and March 2021. High-sensitivity troponin T (hsTnT) was measured pre and 12–18 hours post-procedure. Myocardial injury defined as a post-procedure elevation of hsTnT &gt;5x 99th percentile URL with a normal baseline value or a rise &gt;20% with elevated pre-procedure hsTnT. CTO complexity was described using the J-CTO, PROGRESS, RECHARGE and EuroCASTLE scores [5–8]. Procedures were classified as technical successful or unsuccessful according to CTO academic research consortium (CTO-ARC)criteria [15], and further categorised according to final crossing strategy [antegrade wiring (AW), antegrade dissection re-entry (ADR), retrograde wiring (RW) or retrograde dissection re-entry (RDR)]. If unsuccessful they were further categorised as “failure” or “unplanned modification procedure”. A “planned modification procedure” defined as intentional antegrade modification of the occlusive segment with no attempt to complete CTO crossing.

Results
We analysed 122 CTO PCI procedures. Mean J-CTO, PROGRESS, RECHARGE, EuroCASTLE scores were 2.7, 1.2, 3.0 and 3.1 respectively. Technical success during the index procedure was 75%. An unplanned or planned modification procedure was performed in 16% and 2% of cases, respectively. Technical failure occurred in 7% of cases. Myocardial injury occurred in 65% of all procedures (78% of failed procedures, 64% of successful procedures, 63% of unplanned and none of 3 planned CTO modification procedures). The mean hs-TnT according to treatment strategy and outcomes are reported in Table 1. The relationship between the CTO complexity scores and hs-TnT are illustrated in Figure 1.

Conclusions
Myocardial injury is common during CTO PCI, particularly with more complex anatomy, requiring the retrograde approach or an unplanned modification procedure. A prospective analysis of whether myocardial injury can be avoided using a planned investment procedure in high complexity cases is currently being conducted.

Funding Acknowledgement
Type of funding sources: None.