Cardiac magnetic resonance imaging and follow-up of pacemaker events to identify the etiology and natural history of heart blocks

Background In patients with hemodynamically significant atrioventricular (AV) blocks of unknown etiology, cardiac MRI (CMR) with tissue characterization can provide incremental diagnostic information. Correlation of initial CMR findings with future events recorded by permanent pacemakers (PPM) can characterize the natural history of these serious and potentially life-threatening cardiac conditions. Methods We studied at otal of 78 patients with complete heart block, high-grade second degree heart block and symptomatic bundle branch blocks. In all patients, initial cardiac work-up was non-revealing for potential etiology, and CMR with late gadolinium enhancement (LGE) was performed. Following CMR, most of these patients underwent clinically indicated PPM placement. The interrogated PPM events were followed up for 1-4 years