Intramyocardial Granulomatous Histoplasmosis Presenting as Narrow-Complex Ventricular Tachycardia
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Published on: April 11, 2025
Samarth Goyal1, Stephanie Li1, Alexis Keefe1
1University of Minnesota Medical School, Minneapolis, Minnesota, USA.
Background:
Cardiac histoplasmosis is rare, typically manifesting as pericarditis or endocarditis; tissue-proven intramyocardial granulomatous histoplasmosis has not been previously described.
Case Summary:
A 77-year-old man with immunosuppression presented with acute hypoxemic respiratory failure and recurrent narrow-complex tachyarrhythmias attributed to supraventricular tachycardia (SVT). Echocardiography showed a hyperechoic basal septal mass. Autopsy confirmed a 1.8 × 1.1 cm partially hyalinized necrotizing granuloma of the high interventricular septum containing Histoplasma on silver staining. Retrospective aVR algorithm analysis reclassified the arrhythmia as ventricular tachycardia (VT), anatomically concordant with the granuloma.
Discussion:
Granulomatous histoplasmosis of the upper interventricular septum can produce high septal VT mimicking SVT, expanding the differential of granulomatous myocarditis in immunocompromised hosts.
Take-Home Messages:
Histoplasmosis should be included in the differential of granulomatous myocarditis, particularly in immunocompromised patients from endemic regions. Systematic use of the Vereckei aVR algorithm can prevent misclassification of relatively narrow-complex VT as SVT and guide management.
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