An owner of Thoratec (NSDQ:THOR) stock is suing the heart pump maker on behalf of himself and other shareholders, accusing the medical device company of failing to warn investors about a blood clot problem with its HeartMate II implant implicated in a Class I recall.

The FDA in 2012 classed a Thoratec field correction as a Class I recall, saying an improperly connected component may result in deformation or tearing of the device’s outflow conduit, creating the risk of serious injury or death. Last year a study, published in the New England Journal of Medicine, documented a sharp increase in the rate of blood clots with the HeartMate II left ventricular assist device. Each episode pushed THOR share prices down.

That’s prompted Bradley Cooper to sue on behalf of anyone who bought the stock between April 29, 2010, and Nov. 27, 2013. Cooper alleges that Thoratec misled investors about the risk of thrombosis, or blood clots, in the HeartMate II device. He bought a total of 460 Thoratec shares between July 2010 and July 2013, according to court documents; a block of 200 shares July 27, 2010 for $44.29 apiece; another 30 shares at $42.80 the next day; and a final 230-share block for $31.21 apiece on July 15, 2013.

The stock was trading at $34.34 per share as of about 11:35 a.m. today, down 0.1%.

"As a result of defendants’ wrongful acts and omissions, and the precipitous decline in the market value of the company’s securities, plaintiff and other class members have suffered significant damages," according to the lawsuit.

The Pleasanton, Calif.-based device maker issued a correction notice in February 2012, warning physicians that a small portion of the HeartMate II devices’ sealed outflow graft bend reliefs, designed to prevent a connector between the pump and the aorta from kinking, were not properly connected.

The issue was reported in less than 1% of 3,200 devices and most cases were discovered in X-ray images or during surgical procedures. It may have been a contributor to at least 1 patient’s need for replacement surgery. Detached bend reliefs can cause low or fluctuating pump flow, hemolysis, varying speed and/or power or worsening symptoms of heart failure, and "may cause serious adverse health consequences, including death," according to the FDA.

"The firm states that the device labeling has been revised to provide instructions on how to verify the bend relief is fully engaged with the sealed outflow graft at the time of implant and new caution statement regarding the bend relief connection are included," according to the FDA warning. "Clinicians have been instructed to follow the revised instructions for use that clarify the recommended procedure for securing the bend relief to the outflow graft."

Then, last November, the NEJM article reported a sharp increase in rates of blood clots in patients implanted with the HeartMate II, using data from 3 centers that implanted more than 830 of the devices from January 2004 through May 2013. Data from 3 centers that implanted 895 HeartMate II LVADs in 837 patients from January 2004 through May 2013 showed a total of 72 confirmed cases of pump thrombosis in 66 patients and another 36 cases of suspected pump thrombosis. Of note were a drastic increase after March 2011, according to the study, when rates jumped from 2.2% at 3 months to 8.4% by January 2013. The study also revealed a sharp decrease in the amount of time from implantation with the HeartMate II device until blood clots developed.

Earlier this month Thoratec CEO Gary Burbach said the NEJM study, involving by then year-old data from only 3 centers, obscured the fact that adverse events associated with the HeartMate II are down.

"The broader context is that survival has actually improved since the clinical trial, quite significantly here in the commercial experience," Burbach said at the J.P. Morgan healthcare conference in San Francisco. "We’ve also seen significant improvements in other areas – adverse events, stroke, bleeding and infection, in particular."

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