Correlation of Pre-Explant Lactate Dehydrogenase Concentrations and Findings During Post-Explant Pump Analysis of the HeartMate II Left Ventricular Assist Device.

BACKGROUND: Analyses of the HeartMate II left ventricular assist device are routinely performed after explant if returned to the manufacturer. Findings from manufacturer-reported pump analyses have not been correlated with pre-explant serum lactate dehydrogenase (LDH) values.

METHODS: Between May 2004 and December 2014, 502 patients underwent primary HeartMate II implantation. Seventy pumps were explanted in 58 patients and returned to the manufacturer for pump analysis: 51 (73%) for suspected pump thrombosis, 12 (17%) for device-related infection, and 7 (13%) for percutaneous lead fracture. Median time from implant to explant was 12.4 months (range, 1 to 57 months).

RESULTS: Pump thrombus was confirmed in 53 of 70 pumps (76%). Stratified by major clinical indications for explant of suspected pump thrombus or infection and lead fracture, the presence of pump thrombus was identified in 47 of 51 (92%) and 6 of 19 (32%), respectively. The median of 1) all LDH values, 2) maximum LDH values, and 3) interval change in LDH between 6 and 2 months before device explant were 1,061, 1,940, and -27 IU/L with thrombus present and 533, 504, and 13 IU/L in the absence of thrombus. Density estimation of LDH concentrations identified that a LDH value of 1,155 IU/L in the 6 months preceding pump thrombus had a 78% sensitivity and 90% specificity for findings of pump thrombus at the time of pump analysis.

CONCLUSIONS: Pre-explant LDH concentrations significantly correlated with findings on manufacture-performed pump analysis. These data validate LDH surveillance as an important clinical tool for identification of pump thrombus.