PHOENIX – A blood lactate dehydrogenase level of at least 1,150 IU/L may be the best cutoff for identifying pump thrombosis in patients who have received a left ventricular assist device based on findings from a combined series of 502 pump recipients.
Using this cutoff correlated with a positive predictive value of 74% and a negative predictive value of 92%, Dr. Vikram Sood said at the annual meeting of the Society of Thoracic Surgeons.
Results from several prior studies had established an elevated blood level of lactate dehydrogenase (LDH) as perhaps the best early flag of significant thrombus inside of a left ventricular assist device (LVAD), a condition called pump thrombosis. But prior studies had not identified a specific cutoff value to use that could confidently diagnose pump thrombosis. A level of 1,150 IU/L is about five times the upper limit of normal, noted Dr. Francis D. Pagani , professor of surgery and surgical director of adult heart transplantation at the University of Michigan, Ann Arbor, and a senior author on this report.
Dr. Sood and his associates reviewed records for 502 patients who received a HeartMate II LVAD at either the University of Michigan or at the Mayo Clinic in Rochester, Minn., during 2004-2014. During that time, 58 of the patients required a total of 70 LVAD explants. Fifty-two of the explants were for suspected pump thrombosis, 12 for infection, and 6 for lead fracture. The average time from LVAD placement to explant was 12 months.
Among the 52 LVADs explanted for suspected pump thrombosis, 47 actually had thrombosis. In addition, six of the LVADs that were explanted for other reasons also had a significant amount of thrombus, resulting in 53 total explanted LVAD with confirmed pump thrombosis.
The researchers analyzed blood levels of LDH during the 6 months prior to explant. Among the patients with the 53 LVADs explanted with confirmed pump thrombosis, the median of all LDH levels during the period was 1,061 IU/L and the median maximum LDH level for each patient was 1,940 IU/L, reported Dr. Sood, a cardiac surgeon at the University of Michigan. In contrast, among the patients who had a total of 17 LVADs explanted without pump thrombosis, the median value for all LDH measures during the 6 months prior to explant was 533 IU/L, and their medium maximum level was 504 IU/L.
Analysis of LDH levels prior to explant and subsequent confirmation of pump thrombosis identified a cut off of 1,150 IU/L as able to identify pump thrombosis with a sensitivity of 78% and a specificity of 90%, Dr. Sood reported.
On Twitter @mitchelzoler