Disparity between estimates and measures of maximum heart rate in pilots with coronary artery disease

Background : Several studies indicate that HRmax estimates using the traditional equation, HRmax = 220 - Age, may represent a regression slope and intercept that does reflect the true relationship between age and maximal cardiac frequency. Meta-analysis of several pertinent studies indicates that 220-Age significantly under-estimates the true HRmax, particularly in older patients. This is a critical issue in the exercise evaluation of pilots with CAD who seek reinstatement of an aviation medical certificate after a cardiac illness because end-points in exercise testing and fitness assessment are based upon the 220--Age method of HRmax estimation. Objective: This study was conducted to assess the accuracy of HRmax estimates made with the traditional method, 220-Age, in pilots with coronary artery disease Methods: Nineteen male pilots, aged 46 to 82 years, with a history of CABG or multi-vessel PCI, exercised to exhaustion on a Bruce treadmill protocol. HRmax was measured from continuous 12-lead ECG and regressed on age by linear methods. The resulting regression equation was compared to other equations, including 220-Age. Results: Measured HRmax was highly correlated with age (r = -0.95) and represented by the regression equation, HRmax = 226 – Age. HRmax estimates generated by the 220-Age method were significantly less (p<0.001) than measured HRmax. Conclusions: The traditional method for predicting HRmax under-estimates the maximal cardiac frequency in male pilots with CAD. The accuracy of HRmax estimation for pilots with CAD was not improved by using regression equations derived by meta-analysis of several hundred studies.