Heart rate response to exercise stress testing in asymptomatic women: the st. James women take heart project.
BACKGROUND
The definition of a normal heart rate (HR) response to exercise stress testing in women is poorly understood, given that most studies describing a normative response were predominately based on male data. Measures of an attenuated HR response (chronotropic incompetence) and age-predicted HR have not been validated in asymptomatic women. We investigated the association between HR response to exercise testing and age with prognosis in 5437 asymptomatic women.


RESULTS
Participants underwent a symptom-limited maximal stress test in 1992. HR reserve (change in HR from rest to peak), chronotropic index, and age-predicted peak HR were calculated. Deaths were identified to December 31, 2008. Mean age at baseline was 52+/-11 years, with 549 deaths (10%) over 15.9+/-2.2 years. Mean peak HR was inversely associated with age; mean peak HR=206-0.88(age). After adjusting for exercise capacity and traditional cardiac risk factors, risk of death was reduced by 3% for every 1-beat-per-minute increase in peak HR, and by 2% for every 1-beat-per-minute increase in HR reserve (P<0.001). Inability to achieve 85% age-predicted HR was not an independent predictor of mortality, but being >/=1 SD below the mean predicted HR or a chronotropic index <0.80 based on the prediction model established by this cohort were independent predictors of mortality (P<0.001 and P=0.023, respectively).


CONCLUSIONS
Chronotropic incompetence is associated with an increased risk of death in asymptomatic women; however, the traditional male-based calculation overestimates the maximum HR for age in women. Sex-specific parameters of physiological HR response to exercise should be incorporated into clinical practice.
Gulati
Martha
M
Department of Medicine Cardiology and Preventive Medicine, Northwestern University, Chicago, Ill 60611, USA. m-gulati@northwestern.edu
Shaw
Leslee J
LJ
Thisted
Ronald A
RA
Black
Henry R
HR
Bairey Merz
C Noel
CN
Arnsdorf
Morton F
MF
D000328:Adult; D000367:Age Factors; D000375:Aging / Q000502:physiology*; D003643:Death; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D012307:Risk Factors; D012727:Sex Characteristics