Abrupt flow decline as the initial indicator of early HeartMate 3 pump thrombosis.

Pump thrombosis shortly after HeartMate 3 (HM3) implantation is rare. We report a man in his 50s who developed pump thrombosis 14 days after HM3 implantation. The patient initially presented with an abrupt decline in pump flow accompanied by only mild laboratory abnormalities, while remaining clinically stable. Contrast-enhanced computed tomography raised suspicion of thrombus formation within the outflow graft, prompting emergent pump exchange. Subsequent manufacturer analysis demonstrated thrombus attached to the metallic edge at the inflow aspect of the pump, with no thrombus identified in the rotor or on the blade surfaces. This case highlights the challenges in the early detection and prediction of early HM3 pump thrombosis and the limitations of relying solely on laboratory findings. An abrupt decline in pump flow-even in the absence of marked hemolysis or increased pump power-may represent an early and clinically important warning indicator. Prompt recognition and intervention are essential to prevent clinical deterioration.