Summary of R01HL066004

Project: “Heart Rate Recovery and Mortality”
PI:                   Michael S Lauer, MD
Organization: Cleveland Clinic

During exercise, heart rate increases to meet increasing muscle demands for blood.  Immediately after exercise, heart rate decreases.  We call the decrease in heart rate after exercise “heart rate recovery.”  Scientists believe that heart rate recovery reflects the the “autonomic nervous system,” the part of the nervous system that we are not aware of.  It regulates “automatic” functions like heart rate, blood pressure, and breathing.  It turns out that heart rate falls faster in people who are in good physical shape.  In work we did before getting this grant, we found that slower falls in heart rate predicted a higher risk of early death. 

In this project, we analyzed data from tens of thousands of Cleveland Clinic patients who had exercise tests as part of their routine care.  Our technicians recorded heart rate every few minutes during exercise and one minute after exercise. 

These were some of our main findings:

  • We confirmed that heart rate recovery predicts death.
  • Heart rate recovery is lower in people with diabetes and in people who have more severe heart disease; even so, low heart rate recovery predicts death in people with diabetes and in people with severe heart disease.
  • Heart rate recovery is lower in older adults, and predicts death in older adults.
  • Heart rate recovery is lower in people who are poor (in terms of money).  We thought this might be true because some scientists think that people who are poor may suffer from problems with their nervous systems.  Our finding may help us understand why poor people have higher risks of early death.
  • We found that extra heart beats after exercise also predicts death.  This finding may shed light on why people with low heart rate recovery have a higher risk of death: their nervous system problems may increase the risk of electrical problems with their hearts.