Feasibility of cardiac magnetic resonance for assessing atrioventricular block in acute myocarditis.

AIM: The aim of this study was to evaluate atrioventricular block (AVB) in acute myocarditis (AM) patients and compare the differences between the non-AVB and AVB groups, as well as between nonadvanced AVB and advanced AVB subgroups using cardiac magnetic resonance (CMR).

MATERIALS AND

METHODS

This retrospective single-centre study enrolled 105 AM patients admitted between June 2018 and April 2024 (53 non-AVB, 34 nonadvanced AVB,and 18 advanced AVB patients). CMR functional and tissue parameters were analysed. Adverse clinical outcomes were defined as death, heart failure decompensation requiring hospital readmission, or implantable cardioverter-defibrillator or cardiac resynchronisation therapy implantation.

RESULTS

A total of 105 patients were included (49.50% male), with a median age of 34 years. Most patients showed no evidence of ongoing AVB during CMR examination. The AVB group exhibited a significantly increased heart rate (HR) and reduced left ventricular ejection fraction (LVEF) (both p<0.05). The advanced AVB group had elevated extracellular volume (ECV) values across multiple segments (all p<0.05), while other tissue parameters had no significant differences. Additionally, the ECV of the basal superior ventricular septum effectively discriminated advanced AVB from nonadvanced AVB. Notably, adverse events occurred exclusively in three advanced patients with elevated ECV of the basal superior ventricular septum (p=0.016).

CONCLUSION

Increased ECV of the basal superior ventricular septum independently distinguished advanced AVB from nonadvanced AVB and was related to poor clinical outcome.