Bicarbonate refractory QRS prolongation and left bundle-branch block following escitalopram and lamotrigine overdose: A case report and literature review of toxic left bundle-branch block.

WHAT IS KNOWN AND

OBJECTIVE

Toxic prolongation of the QRS interval most often results from blockade of cardiac voltage-gated sodium channels and manifests on electrocardiogram with a right bundle-branch block-like morphology. Rarely, a left bundle-branch block (LBBB) morphology has been reported.

CASE REPORT: We report a case of transient LBBB resultant from ingestion of lamotrigine and citalopram which was refractory to sodium bicarbonate therapy and eventually resolved spontaneously.

WHAT IS NEW AND

CONCLUSION

Cases of toxic LBBB are less likely to respond to bicarbonate therapy, suggesting that this finding is due to a mechanism other than sodium channel blockade.