for bridge-to-transplantation (BTT) use in April 2008, and for destination therapy (DT) for those too old or ill for a heart transplant in January 2010. The company therefore discontinued its first-generation HeartMate XVE in 2011. In July 2009, the Journal of the American College of Cardiology reported on 18-month follow-up data for the HeartMate II Pivotal Study, which showed improved survival, less frequent adverse events, and greater reliability with continuous-flow LVADs compared to pulsatile-flow devices. As of mid 2015, Thoratec has the only FDA-approved LVAD for destination therapy, or permanent support; the ventricular assist system by competitor HeartWare Inc. is still in clinical trials for destination therapy. In a two-year randomized controlled clinical trial published in 2009 comparing pulsatile and continuous-flow LVADs, survival rates at two years increased approximately six-fold for HeartMate II patients compared to actuarial survival rates for patients who receive only drug therapy. In the 2005–2007 and 2007–2009 HeartMate II destination-therapy trials, more than 80% of patients implanted with the HeartMate II improved to NYHA class I/II from NYHA class III/IV by six months after implantation, and this improvement remained stable for two years. The patients' six-minute walk distance improved to >340 meters by six months and was sustained through two years. In January 2010 Thoratec acquired catheter-based heart pump technology from the Swedish medical-technology company Getinge. The technology is for use in a minimally invasive, acute cardiac axial-flow pump that can be delivered percutaneously in a cardiac catheterization lab or operating room. In August 2011 Thoratec acquired the medical business of Levitronix. The acquisition included CentriMag, an extracorporeal centrifugal-flow blood pump used for short-term surgical support, and the PediMag, an acute pediatric surgical circulatory support system known as PediVAS outside the U.S. In July 2013, Thoratec acquired the DuraHeart II ventricular assist system from medical-equipment manufacturer Terumo. According to the press release, the device further differentiates Thoratec's approach to mechanical circulatory support, and is expected to begin in-human implantation in 2016 followed by clinical trials. A study published in November 2013 by the New England Journal of Medicine reported an unexpected increase in blood clots (thrombosis) in the HeartMate II from March 2011 through January 2013 and thereafter, at three institutions. Another analysis at three other institutions including the Mayo Clinic reported a similar thrombosis increase with a peak in 2012; however thereafter the incidence decreased by 2013 to post-marketing (2007) levels. In March 2014 Thoratec