Conference Coverage
STS: Lactate dehydrogenase of 1,150 IU/L flags LVAD thrombosis
Key clinical point: In patients who have received a left ventricular assist device, a blood level of lactate dehydrogenase of at least 1,150 IU/L...
The issue of LVAD pump thrombosis first came into clear focus with publication at the start of 2014 of a report that tracked its incidence from 2004 to mid-2013 at three U.S. centers that had placed a total of 895 LVADs in 837 patients. The annual rate of new episodes of pump thrombosis jumped from about 1%-2% of LVAD recipients throughout the first part of the study period through the end of 2011, to an annual rate of about 10% by mid 2013 (N Engl J Med. 2014 Jan 2;370[1]:33-40).
“The inflection occurred in about 2012,” noted Dr. Nicholas G. Smedira, a cardiothoracic surgeon at the Cleveland Clinic. “No one has figured out why” the incidence suddenly spiked starting in 2012 and intensified in 2013, he said. This epidemic of pump thrombosis has produced “devastating complications” that have led to multiple readmissions and reduced cost-effectiveness of LVADs and has affected how the heart transplant community allocates hearts, Dr. Smedira said during his talk at the session. He noted that once the surge in pump thrombosis started, the timing of the appearance of significant thrombus shifted earlier, often occurring within 2-3 months after LVAD placement. There now is “increasing device-related pessimism” and increasing demoralization among clinicians because of this recurring complication, he said.
Mitchel L. Zoler/Frontline Medical News
Dr. Nicholas Smedira
More recent data show the trend toward increasingly higher rates of pump thrombosis continuing through the end of 2013, with the situation during 2014 a bit less clear. Late last year, data from 9,808 U.S. patients who received an LVAD and entered the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) showed that the incidence of pump thrombosis during the first 6 months following an implant rose from 1% in 2008 to 2% in 2009 and in 2010, 4% in 2011, 7% in 2012, 8% in 2013, and then eased back to 5% in the first half of 2014 (J Heart Lung Transplant. 2015 Dec;34[12]:1515-26). The annual rate rose from 2% in 2008 to a peak of 11% in 2013, with 12-month data from 2014 not yet available at the time of this report.
“The modest reduction of observed pump thrombosis at 6 months during 2014 has occurred in a milieu of heightened intensity of anti-coagulation management, greater surgical awareness of optimal pump implantation and positioning and pump speed management. Thus, one may speculate that current thrombosis risk-mitigation strategies have contributed to reducing but not eliminating the increased thrombosis risk observed since 2011,” concluded the authors of the report.
Surgeons and cardiologists must now have a high index of suspicion for pump thrombosis in LVAD recipients, and be especially on the lookout for four key flags of a problem, said Dr. Kormos. The first is a rising LDH level, but additional flags include an isolated power elevation that doesn’t correlate with anything else, evidence of hemolysis, and new-onset heart failure symptoms. These can occur individually or in some combination. He recommended following a diagnostic algorithm first presented in 2013 that remains very valid today (J Heart Lung Transplant. 2013 July;32[7]:667-70).
Dr. Kormos also highlighted that the presentation of pump thrombosis can differ between the two LVADs most commonly used in U.S. practice, the HeartMate II and the HeartWare devices. A LDH elevation is primarily an indicator for HeartMate II, while both that model and the HeartWare device show sustained, isolated power elevations when thrombosis occurs.
Dr. Pagani, Dr. Kirklin, and Dr. Smedira had no disclosures. Dr. Kormos has received travel support from HeartWare. Dr. Kilic has been a consultant to Thoratec and a speaker on behalf of Baxter International.
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