Each business day, TheStreet.com Ratings TheStreet.com Ratings compiles a list of the top five stocks in one of five categories -- fast-growth, all-around value, large-cap, mid-cap and small-cap -- based on data from the close of the previous trading session. Today we focus on mid-caps.These are stocks of companies that have market capitalizations of between $500 million and $10 billion that rank near the top of all stocks rated by our proprietary quantitative model, which looks at more than 60 factors. The stocks must also be followed by at least one financial analyst who posts estimates on the Institutional Brokers' Estimate System. They are ordered by their potential to appreciate. Note that no provision is made for off-balance-sheet assets such as unrealized appreciation/depreciation of investments, market value of real estate or contingent liabilities that might affect book value. This could be material for some companies with large underfunded pension plans. Edwards Lifesciences ( EW) is a global provider of products and technologies designed to treat advanced cardiovascular disease. The company has been rated a buy since February 2007. This rating is supported by the company's efficiency, solvency, and growth in net income, revenue and EPS. Edwards Lifesciences reported that its results in the first quarter of fiscal 2009 were due in part to strong heart valve sales. Although the company's revenue was less than that of the industry average, it was able to report an increase of 5.6% year over year. This growth appears to have been enough to have helped boost EPS, which showed significant improvement when compared to the prior year's quarter, rising from 31 cents to $1.03 per share. We feel that the company's trend of positive EPS growth over the past two years should continue going forward. Net income surged in the fourth quarter, rising 232.4% from $18.2 million to $60.5 million. Edwards' very low debt-to-equity ratio of 0.1 indicates that the company has been very successful at debt management, while a quick ratio of 2 demonstrates the ability to cover short-term liquidity needs. An additional sign of strength for the company is its expanding return on equity, which increased from 12.6% to 18.2% over the past year.