Non-Contrast cardiac magnetic resonance for left atrial appendage occlusion Planning: A comparative study with cardiac CTA.

Background

Accurate preprocedural imaging is essential for left atrial appendage occlusion (LAAO) device sizing. Although cardiac CT angiography (CCTA) is widely used, radiation and contrast limit its use.

Purpose

To assess non-contrast cardiac MR (CMR) for LAAO planning by comparing measurements with CCTA and digital subtraction angiography (DSA), evaluating agreement with implanted device size, and predicting optimal fluoroscopic projection angles (OPA).

Materials And Methods

Thirty-two patients with atrial fibrillation scheduled for LAAO (April 2024-October 2025) underwent non-contrast CMR and CCTA before DSA. Landing zone dimensions and morphology were assessed using identical 3D multiplanar protocols. Area-derived equivalent diameter was used for sizing. OPA predicted by CMR and CCTA were compared with DSA. Agreement with final device size was analyzed using Bland-Altman plots.

Results

Thirty patients (mean age 66.9 years) completed both exams; LAAO succeeded in 29 (96.7 %). CMR and CCTA showed no significant differences in landing zone measurements (area: 521.2 ± 210.0 vs 523.9 ± 225.9 mm2,p = 0.759; area-derived diameter: 25.3 ± 5.1 vs 25.5 ± 5.4 mm,p = 0.475). DSA maximum diameter was smaller than direct CMR/CCTA diameters (p < 0.05) but similar to area-derived diameters (p = 0.355). CMR area-derived diameter closely agreed with device size (bias - 2.76 mm; limits - 6.97 to 1.45 mm), comparable to CCTA. Predicted OPA from CMR agreed with DSA and CCTA.

Conclusion

Non-contrast CMR provides measurements and OPA prediction comparable to CCTA, supporting its feasibility as a radiation- and contrast-free alternative for selected patients.