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 of HeartMate 3 pump thrombosis.
A patient developed HeartMate 3 pump thrombosis 14 days after implantation, which is described as a rare early occurrence.
The initial presenting sign of pump thrombosis was an abrupt decline in pump flow, with only mild laboratory abnormalities and clinical stability.
Contrast-enhanced computed tomography raised suspicion of thrombus formation within the outflow graft, prompting emergent pump exchange.
Manufacturer analysis of the explanted pump revealed thrombus attached to the metallic edge at the inflow aspect of the pump, with no thrombus in the rotor or on blade surfaces.
Abrupt pump flow decline without marked hemolysis or increased pump power may represent an early and clinically important warning indicator of HM3 pump thrombosis.
This research describes a case report of a man in his 50s who developed a blood clot (thrombus) inside his HeartMate 3 (HM3) left ventricular assist device (LVAD) — a mechanical heart pump — just 14 days after it was implanted. This type of early pump clotting is considered rare with the HM3 device. Importantly, the first sign that something was wrong was a sudden drop in how much blood the pump was moving, even though the patient felt relatively well and standard blood tests showed only mild abnormalities. A CT scan with contrast dye ultimately identified the suspected clot, and the pump had to be urgently replaced. When the removed pump was analyzed, the clot was found attached to a metal edge at the pump's inlet, with no clotting found on the spinning rotor or blade surfaces. This research suggests that doctors and clinical teams managing patients with the HM3 device should pay close attention to sudden drops in pump flow, even when patients appear stable and blood tests do not show obvious signs of clotting or blood cell damage (hemolysis). Traditionally, pump thrombosis has been detected by looking for elevated pump power consumption or blood markers of hemolysis, but this case shows those signs may not always be present early on. The unusual location of the clot — at the inflow metal edge rather than the rotor — may explain why typical warning signs were absent. This case highlights a diagnostic challenge: early HeartMate 3 pump thrombosis can be subtle and may not trigger the usual laboratory alarms. This research suggests that an abrupt, unexplained decline in pump flow should be treated as a potential early warning sign requiring prompt investigation, including advanced imaging, to avoid life-threatening deterioration.
Ishii Y, Kato T, Takagi K, Sano S, Yoshimatsu S, Shinoda M, et al.. (2026). Abrupt flow decline as the initial indicator of early HeartMate 3 pump thrombosis.. Journal of artificial organs : the official journal of the Japanese Society for Artificial Organs. https://doi.org/10.1007/s10047-026-01588-1