Based on Colonial Life claims statistics, heart attacks, strokes and coronary artery bypass surgeries accounted for 58 percent of critical illness claims in 2010. Cancer made up 35 percent while other conditions, including kidney failure and transplants, made up the rest of the claims.

"National Heart Month in February is a perfect reminder to think about whether you have enough insurance protection for a critical illness such as a heart attack," says Randy Finn, assistant vice president, product development for Colonial Life. "Not only can these illnesses can be extremely expensive to treat, there are often significant nonmedical expenses, so even employees with good major medical coverage may be left with large bills unpaid."

Unless specified otherwise, voluntary critical illness plans pay benefits, which can be used for nonmedical or uncovered expenses, directly to the insured individuals. With a critical illness plan, people who suffer a medical emergency do not have to use their savings or borrow money to cover their expenses. According to a 2008 Kaiser tracking poll, nearly a third of Americans report having trouble paying medical bills, with 18 percent saying bills climbed an excess of $1,000.