What is the fine-grained topic of the following text: New York, NY (November 3, 2009) — People with chronic kidney disease are at much greater risk of developing heart problems than people with healthy kidneys, but new data from the U.S. Renal Data System (USRDS) shows some major improvements in their heart health. Only return the topic.
Improvements in heart health of people with chronic kidney disease according to USRDS data.