Novel predictor of prognosis from exercise stress testing: Heart rate variability response to the exercise treadmill test

• Published in: The American heart journal 2007-02, Vol.153 (2), p.281-288
• Main Authors: Dewey, Frederick E., BA, Freeman, James V., MD, Engel, Gregory, MD, Oviedo, Raul, MD, Abrol, Nayana, MD, Ahmed, Natasha, MD, Myers, Jonathan, PhD, Froelicher, Victor F., MD
• Format: Article
• Language: English
• Subjects: Accuracy; Age; Biological and medical sciences; Cardiology. Vascular system; Cardiovascular; Exercise; Exercise Test; Female; Fitness equipment; Follow-Up Studies; Fourier transforms; Heart attacks; Heart failure; Heart rate; Heart Rate - physiology; Humans; Male; Medical sciences; Middle Aged; Mortality; Predictive Value of Tests; Prognosis; Regression analysis; Retrospective Studies; Risk factors; Statistical methods; Studies; Variables
• ISSN: 0002-8703; 1097-6744
• DOI: 10.1016/j.ahj.2006.11.001

Background Although the prognostic power of heart rate variability (HRV) at rest has been demonstrated, the prognostic potential of exercise-induced HRV has not been investigated. We aimed to evaluate the prognostic power of exercise-induced HRV during and after standard exercise testing. Methods Time- and frequency-domain HRV analysis was performed on R-R interval data taken from 1335 subjects (95% male, mean age 58 years) during the first and last 2 minutes of exercise treadmill testing and the first 2 minutes of recovery. Cox survival analysis was performed for the 53 cardiovascular and 133 all-cause mortality end points that accrued during the 5.0-year mean follow-up. Results After adjusting for potential confounders, greater root mean square successive difference in R-R interval during peak exercise and recovery, greater high-frequency (HF) power and percentage of HF power, lower percentage of low-frequency power, and lower ratio of low frequency to HF during recovery were significantly associated with increased risks for all-cause and cardiovascular death. Of all time-domain variables considered, the log of the root mean square successive difference during recovery was the strongest predictor of cardiovascular mortality (adjusted hazard ratio 5.0, 95% CI 1.5-17.0 for the top quintile compared with the lowest quintile). Log HF power during recovery was the strongest predictor of cardiovascular mortality in the frequency domain (adjusted hazard ratio 5.9, 95% CI 1.3-25.8 for the top quintile compared with the lowest quintile). Conclusions Exercise-induced HRV variables during and after clinical exercise testing strongly predict both cardiovascular and all-cause mortality independent of clinical factors and exercise responses in our study population.