The Role of Cardiac MRI in Guiding Revascularization Strategy in Patients with Reduced Left Ventricular Ejection Fraction: A Comparative Evaluation of CABG and PCI

Background: Cardiac magnetic resonance (CMR) imaging is a key non-invasive tool for assessing myocardial viability and guiding treatment in patients with reduced left ventricular ejection fraction (LVEF). This study aimed to evaluate the impact of a CMR-guided revascularization strategy on the dynamics of left ventricular (LV) function, and to compare outcomes between coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI).

Methods: A total of 416 patients with LVEF < 35% were included. Group I (n=192) underwent CMR-based viability assessment to guide revascularization strategy. Group II (n=224) was retrospectively analyzed, with revascularization guided by angiographic complexity. Patients were further stratified by anatomical completeness of revascularization (complete vs incomplete). Serial assessments of LVEF were performed at 12, 18, and 24 months.

Results: At 12 months, both groups demonstrated non-significant improvement in LVEF (Group I: 31.18 ± 2.58% to 34.74 ± 3.98%, p=0.6533; Group II: 31.08 ± 2.53% to 34.97 ± 5.61%, p=0.1280). However, by 18 months, Group I (CMR-guided) showed a significant increase in LVEF (34.74 ± 3.98% to 41.91 ± 4.16%, p=0.0009), whereas the increase in Group II remained non-significant (p=0.0897). This trend continued at 24 months, with Group I reaching 46.8 ± 2.92% (p=0.00001), compared to 42.71 ± 4.99% in Group II (p=0.0727).

Subgroup analysis comparing CABG and PCI showed comparable improvements in LVEF at each time point (12, 18, and 24 months), with no significant differences between techniques (p>0.05 at all time points). Similarly, comparisons between anatomically complete and incomplete revascularization subgroups did not reveal significant differences, suggesting that functionally complete revascularization may be achieved despite anatomical limitations.

Conclusion: A revascularization strategy guided by CMR-assessed myocardial viability is associated with superior long-term improvement in LV function compared to conventional angiography-guided decision-making. Importantly, both CABG and PCI demonstrated equivalent efficacy in LVEF improvement when guided by viability, and incomplete anatomical revascularization may still be functionally adequate. These findings underscore the critical role of CMR in optimizing treatment strategy in patients with severely reduced LVEF.