Three US centers report increasing rates of pump thrombosis related to the use of the HeartMate II left ventricular assist device and an association with substantial morbidity and mortality.
“Pivotal trials and postmarketing approval studies of the HeartMate II provide a reference occurrence of thrombosis of 2% to 4%; however, an unexpected abrupt increase in the incidence of pump thrombosis was observed in a single-center quality review,” Randall C. Starling, MD, MPH, of Cleveland Clinic, and colleagues wrote in The New England Journal of Medicine. “To confirm that this finding was not an isolate phenomenon, two additional experienced centers pooled data to investigate the incidence of pump thrombosis and of elevated lactate dehydrogenase (LDH) levels as its clinical biomarker (indicating hemolysis), LDH levels that may presage thrombosis and outcomes of thrombosis-management strategies.”
The analysis included data on 837 patients and 895 HeartMate II devices (Thoratec) that were implanted from 2004 to mid-2013 at Cleveland Clinic, Duke University Medical Center and Washington University Barnes-Jewish Hospital.
Confirmed pump thrombosis served as the primary endpoint. According to results, 72 pump thromboses were confirmed in 66 patients. Thirty-six additional thromboses of unique devices were suspected.
From March 2011 to January 2013, the occurrence of confirmed pump thrombosis at 3 months post-implantation increased from 2.2% to 8.4%. The median time from implantation to thrombosis decreased, from 18.6 months before March 2011 to 2.7 months after March 2011.
An increased occurrence of elevated LDH levels at 3 months post-implantation also increased during the study period. Thrombosis was presaged by LDH levels that increased from 540 IU/L to 1,490 IU/L in the weeks before diagnosis, according to the study results.
Eleven patients had their pump thrombosis managed by heart transplantation; one patient died 31 days after transplantation. Twenty-one patients had their thrombosis managed by pump replacement. In this group, mortality was similar to that of patients with no thrombosis. The researchers also reported data on 40 thromboses in 40 patients not managed by transplantation or pump replacement; in the 6 months after pump thrombosis, the actuarial mortality was 48.2%.
“Further investigation of predisposing patient and device factors and preventive and therapeutic strategies are urgently needed to resolve this important safety issue,” the researchers concluded. “We recognize that LVADs provide life-sustaining treatment for many patients with advanced heart failure. However, recommendations for LVAD therapy should account for this updated risk-benefit profile.”
Disclosure: See the full study for a list of the researchers’ relevant financial disclosures.