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


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.


We studied a total 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 to monitor significant arrhythmias or long-term pacemaker dependence.


In patients with heart block, CMR identified a myocardial infiltrative process in 44%. In patients with symptomatic LBBB or RBBB, CMR identified a plausible etiology in approximately 25%. Presence of myocardial LGE by CMR had 90% sensitivity and 80% negative predictive value for long-term pacemaker dependence in patients with complete or high-grade AV blocks.


In addition to the indications attributed in the current diagnostic algorithm, CMR can identify potential cause of hemodynamically significant AV-blocks in over 40% of the patients. Presence of LGE or other major diagnostic findings on CMR can uniquely identify patients with long-term pacemaker dependence.



Figure 1
figure 1

Pie Chart showing the relative distribution of the diagnostic categories of patients with- A) Complete or High-Grade AV-Block, B)RBBB, and C) LBBB.

Figure 2
figure 2

Pacemaker dependeance in patients with and without LGE or CMR.

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This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.

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Carmona-Rubio, A.E., Puchner, S., Lee, A.M. et al. Cardiac magnetic resonance imaging and follow-up of pacemaker events to identify the etiology and natural history of heart blocks. J Cardiovasc Magn Reson 17 (Suppl 1), P172 (2015).

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