Tall men might have less to worry about when it comes to one heart problem.  A new study reveals that they are less likely than short men to have heart failure.A Harvard Medical School researcher says men over six feet tall were 24 percent less likely to report heart failure than those who were five-foot-eight or shorter.  The study looked at more than 20-thousand men over an average of more than 20 years.  Scientists say one factor could be the greater distance between the heart and some blood vessels in taller men.  Results of the study are published in the "American Journal of Cardiology."