Acute Outflow Graft Occlusion—A Novel Predictable Complication of Lysis Therapy for the Treatment of Left Ventricular Assist Device Intra-Pump Thrombosis

Abstract

Lysis therapy is an established treatment option for intra-pump thrombosis of left ventricular assist devices (LVADs). In clinical routine, we observed repeated cases of acute outflow graft occlusions (OGO) associated with lysis therapy with need for urgent intervention. The aim of this investigation was to gain understanding of this observation. We screened data of 962 HeartWare ventricular assist device (HVAD) patients. One hundred twenty (13.8%) had intra-pump thromboses; 58 were treated with recombinant tissue-type plasminogen activator (rtPA). Mean age was 53.0 ± 11.1 years; 84.9% were male. In 13 (24.5%) patients, OGO occurred following rtPA-lysis. These patients showed an increase in left ventricular function (18.45% ± 12.62% to 27.73% ± 10.57%; p = 0.056), more frequent 1:1 aortic valve opening (OGO+: +36.4%; OGO−: +7.4%; p = 0.026), a decrease in LVAD pulsatility within 12 months prior intra-pump thrombosis (OGO+: –0.8 L/min [interquartile range {IQR}, –1.4 to –0.4 L/min]; OGO−: –0.3 L/min [IQR, –0.9 to 0.1 L/min]; p = 0.038) and lower HVAD flows at admission (OGO+: 6.7 L/min [IQR, 6.1–7.4 L/min]; OGO−: 8.3 L/min [IQR, 6.9–9.3 L/min]; p = 0.013), indicating a subclinical OGO prior intra-pump thrombosis. There were no differences in implantation techniques, blood parameters, and lysis strategy. Subclinical OGO represented a major risk factor for acute OGO following rtPA lysis therapy. We here propose an algorithm for risk stratification and dealing with patients presenting this first-described complication. Further research is required to confirm our results and decipher the underlying pathomechanism.