Myocardial Viability and Ischaemia in Chronic Total Occlusion

Area of Science:

• Cardiology
• Medical Imaging
• Biomedical Engineering

Background:

• Chronic total occlusion (CTO) impacts 30% of patients undergoing coronary angiography, leading to poorer outcomes.
• Percutaneous coronary intervention (PCI) for CTO has high technical success but lacks proven survival benefits in randomized controlled trials (RCTs).
• Cardiovascular Magnetic Resonance (CMR) offers comprehensive myocardial phenotyping and prognostic insights for high-risk CTO patients.

Purpose of the Study:

• To evaluate the role of multiparametric CMR in assessing myocardial viability, ischemia, and scar burden in patients with CTO.
• To compare myocardial characteristics between CTO territories with and without viable myocardium.
• To identify CMR-based predictors of non-viability in CTO.

Main Methods:

• Fifty-six patients with angiographically confirmed CTO underwent stress perfusion CMR with late gadolinium enhancement.
• Myocardial function, ischemia, and scar burden were quantified.
• Comparisons were made between CTO territory and viability subgroups.

Main Results:

• 27% of CTO patients (15/56) had no viable myocardium.
• Among patients with viable myocardium, 66% (27/41) showed reversible ischemia.
• Viable myocardium was associated with higher LV stroke volumes, lower LV scar mass and percentage, and more global and CTO-territory ischemia compared to non-viable myocardium.
• A CTO-territory scar burden threshold of 11.18% predicted non-viability with 80% sensitivity and 65.85% specificity (AUC = 0.701).

Conclusions:

• A significant proportion of CTO patients (27%) lack myocardial viability.
• Patients with viable myocardium in CTO territories typically exhibit reversible ischemia, indicating a phenotype of preserved viability with inducible ischemia.
• Multiparametric CMR is valuable for phenotyping CTO territories, aiding decisions regarding CTO-PCI.