The patient’s presentation with SVT, splenomegaly, and a history of unprovoked pulmonary embolism aligns with reports of latent MPNs unmasked by thrombotic events, with JAK2 V617F detected in 32.7% of SVT cases and 49% of idiopathic SVT [6]. Here, JAK2 is linked to Supraventricular tachycardia.