Share prices for St. Jude Medical (NYSE:STJ) slid today after the medical device company missed forecasts for its 4th-quarter sales, despite a higher-than-expected contribution from its newly acquired Thoratec implantable heart pump business, and raised the low end of its earnings outlook.

Little Canada, Minn.-based St. Jude said it expects to post sales of $1.45 billion for the 3 months ended Dec. 31, 2015, missing Wall Street’s forecast for $1.48 billion. Adjusted earnings per share are now forecast for $1.01 to $1.02, up from prior guidance for adjusted EPS of $1.00 to $1.02.

That pushed STJ shares down -1.3% to $58.40 apiece in mid-morning trading, despite solid news from the new Thoratec business, which St. Jude acquired for $3.3 billion last October.

Thoratec’s left-ventricular assist devices put up sales of $136 million, exceeding prior top-line guidance for $125 million to $130 million, St. Jude said. The growth was driven in part by the launch of the next-generation HeartMate 3 device in Europe, the company said.

“We continue to execute our innovation-based growth strategy and made good progress during the 4th quarter in our areas of focus. The pressures to our business that we communicated heading into the quarter were partially offset by continued growth in atrial fibrillation and neuromodulation as well as strong sales from the recent Thoratec acquisition. In 2015, we set the stage to continue to expand our global leadership in heart failure, atrial fibrillation and neuromodulation in 2016,” new president & CEO Michael Rousseau said in prepared remarks.