This case demonstrates that the right bundle branch is rarely involved by a posterior MI, even with a dissecting interventricular septal rupture, and that underlying chronic fibrosis may contribute to new-onset RBBB in this setting.
Chronic fibrosis may drive new RBBB despite posterior MI with septal rupture; leaves open mechanisms in larger cohorts.
We present here a patient with the unusual combination of a newly developed right bundle branch block (RBBB) and an acute posterior myocardial infarction (MI). A dissecting MI with interventricular septal (IVS) rupture was initially thought to have caused RBBB. However, histologic examination revealed that the right bundle branch (RBB) had no ischemic involvement, but did show fibrosis, which suggests that this chronic damage of the RBB was a major contributor to the development of RBBB. This case confirms that the RBB is rarely involved by a posterior MI even in the presence of a dissecting IVS rupture.
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Okabe et al. (1997) studied this question.
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