Physicians from three top institutions report an abrupt and highly troubling increase over the last two years in the incidence of pump thrombosis in patients who have received the HeartMate II left ventricular assist device (LVAD) manufactured by Thoractec.
The current investigation, published online in the New England Journal of Medicine, was initially prompted by an observed increase in pump thrombosis at the Cleveland Clinic. This first led to an analysis performed by INTERMACS (the Interagency Registry for Mechanically Assisted Circulatory Support) which found an increase from 2% before May 2011 to 5% afterwards. But, write the NEJM authors, there is reason to believe the INTERMACS analysis may have underestimated the rate of pump thrombosis. (The INTERMACS data, along with other papers about the problem, have been published in a special issue of the Journal of Heart and Lung Transplantation.)
The new paper is based on pooled data from 895 patient who received the HeartMate II LVAD at the Cleveland Clinic, Barnes-Jewish Hospital, and the Duke University Medical Center . The authors report that after March 2011 the incidence of confirmed pump thrombosis within three months of implantation increased from 2.2% to 8.4% by January 2013.