High blood pressure is one of the most common health problems in the United States. There are many drug treatment options for high blood pressure, but these medications are not always effective. People with treated high blood pressure can still suffer from other serious cardiovascular health problems, including heart attack, sudden death, or stroke. Genetic variations may cause some people to be more susceptible to these cardiovascular outcomes despite treatment. This study will identify new gene regions that may influence the effectiveness of high blood pressure drugs in preventing the above mentioned cardiovascular conditions.