Key result
Intramyocardial histoplasmosis granuloma triggers high septal VT mimicking supraventricular tachycardia.
Why the study?
Cardiac histoplasmosis is rare and typically manifests as pericarditis or endocarditis, whereas tissue-proven intramyocardial granulomatous histoplasmosis had not been previously described.
Case Report (n=1)
This case report presents the first tissue-proven description of intramyocardial granulomatous histoplasmosis of the upper interventricular septum causing narrow-complex ventricular tachycardia mimicking supraventricular tachycardia.
Answers are grounded in this paper and cite their sources.
Rare intramyocardial histoplasmosis may cause narrow-complex VT mimicking SVT; extends cardiac histoplasmosis spectrum but leaves open broader validation.
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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Goyal et al. (2026) conducted a case report in Intramyocardial granulomatous histoplasmosis presenting as narrow-complex ventricular tachycardia (n=1). Intramyocardial granulomatous histoplasmosis was evaluated. Intramyocardial granulomatous histoplasmosis (1.8 × 1.1 cm septal granuloma) caused high septal ventricular tachycardia mimicking supraventricular tachycardia in a 77-year-old man.
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