Cardiac device maker Boston Scientific (NYSE:BSX) has performed well above expectations for investors in 2013. Even with sales in flux, Boston Scientific's stock has more than doubled this year as the firm mitigated hits to its cardiac rhythm management branch while bolstering its investments in emerging technologies.

One of its most promising new markets is atrial fibrillation. This market is expected to boom soon, with research firm Transparency Market Research estimating that the atrial fibrillation market could climb to nearly $15 billion by 2019, with double-digit annual growth. That's the kind of growth that Boston Scientific and its investors would love to capitalize on, and the company's doing its best with its Watchman device for atrial fibrillation.

But will the Watchman perform up to investor hopes? In the video below, Fool contributor Dan Carroll shows how this device is facing its future at the end of this year -- and how Boston Scientific could be on the verge of a major breakthrough.