Magnetic resonance post-contrast T1 mapping in the human atrium: validation and impact on clinical outcome after catheter ablation for atrial fibrillation.

Liang-Han Ling,Geoffrey Lee,Michael A Sellenger,Jonathan M Kalman,Joseph B Morton,Saurabh Kumar,Leah M Iles,Sonia Azzopardi,Michael C.G Wong,Andrew J Taylor,Peter M Kistler,Andris H Ellims,Alex J.A Mclellan,Andrew Teh

doi:10.1016/j.hrthm.2014.06.012

Abstract

The impact of diffuse atrial fibrosis detected by T1 mapping on the clinical outcome after atrial fibrillation (AF) ablation is unknown. This study aimed to validate and assess the impact of post-contrast cardiac magnetic resonance (CMR) imaging atrial T1 mapping on the clinical outcome after catheter ablation for AF. CMR imaging was performed in 3 groups by using a clinical 1.5-T scanner: controls, patients with paroxysmal AF, and patients with persistent AF. A T1 mapping sequence was used to calculate the post-contrast T1 relaxation time (T1 time) at the interatrial septum as an index of diffuse atrial fibrosis. A subset underwent left atrial endocardial bipolar voltage mapping for electrophysiologic correlation. After AF ablation, patients underwent clinical review and 7-day Holter monitoring at 6-month intervals. One hundred thirty-two patients (20 controls, 71 (63%) patients with paroxysmal AF, and 41 (37%) patients with persistent AF) underwent CMR imaging. Post-contrast atrial T1 time was significantly shorter in AF groups (237 ± 42 ms) than in controls (280 ± 37 ms) (P < .001). Post-contrast atrial T1 time correlated with mean septal voltage (R2 = .48; P < .001) and global left atrial voltage (R(2) = .41; P < .001). A diagnosis of AF, AF duration, and left ventricular end-diastolic volume independently predicted shortened post-contrast atrial T1 time. The single procedure success rate was 74% at 12 ± 5 months postablation. Post-contrast atrial T1 time was the only predictor of arrhythmia recurrence in multivariate analysis (P = .015). A post-contrast atrial T1 time of >230 ms was associated with freedom from AF in 85% relative to 62% with a post-contrast atrial T1 time of <230 ms (P = .01). Post-contrast atrial T1 time as measured using CMR imaging provides an index of atrial fibrosis that correlates with tissue voltage, presence of AF, and clinical outcomes after catheter ablation.

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