New Method to Predict Thrombotic Events from VADs Weeks Beforehand

Ventricular assist devices (VADs) are literally life savers for some patients with heart failure, however, the technology can be accompanied by serious risks.

“One of the most serious risks is pump thrombosis characterized by an organized fibrin deposition in the pump, which requires clinical intervention and/or surgical replacement of the device,” researchers from Loyola University Chicago in Illinois described in a poster session at the 57^th American Society of Hematology Annual Meeting (ASH 2015) in Orlando, Florida. The team may have found a new biomarker for earlier detection of pump thrombosis.

The standard way to detect VAD pump thrombosis is to measure plasma lactate dehydrogenase levels (LDH). Numbers that come back more than two times the upper limit of normal are diagnosed. The problem here is that by the time LDH reaches detection level, the patient’s condition is clinically significant. However, the new analysis points to cellular microparticles (MPs) as a possible biomarker.

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“MPs are submicron membrane-derived exocytotic vesicles that are derived from a variety of cell types by outward blebbing of the plasma membrane in response to activation stimuli,” the authors explained.

To find out if MPs were a sufficient biomarker, the team collected blood samples from 13 patients peri-operatively who were implanted with a HeartMate II LVAD and 14 healthy controls. The blood samples were processed to decipher between MPs and biological membranes. There were multiple key takeaways from the findings:

• 11 out of the 13 patients had thrombotic episodes — all of which had elevated MP levels about 50 days before lactate dehydrogenase (LDH) elevation
• 12 out of the 13 patients had elevated platelet counts up to 50 days after surgery, but they were normal during the thrombotic event
• Adverse events did not appear to correlate with INR time out of therapeutic range or any other clinical parameter the study looked at

“Microparticle levels in VAD patients with thrombotic events were shown to cross the normal threshold weeks prior to the time when common clinical parameters indicated an abnormality, suggesting that changed in MP levels may be useful in predicting thrombotic events,” the researchers divulged.

The team acknowledges that further research is warranted to confirm the association, but it could help lead to more effective prophylactic measures in the future.

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