Achieving ≥90% of the Age-Predicted Treadmill Time for Commercial Vehicle Operation Does Not Predict Future Cardiovascular Events.

BACKGROUND

Functional capacity (FC) has been shown to be a strong independent predictor of all-cause and cardiovascular (CV) mortality. Nomograms based on age and sex have been developed to standardise exercise times and FC during treadmill testing (TT). Many patients with prior CV disease perform TT as a requirement for commercial vehicle operation. The current recommendations state a level ≥90% of FC for age should be achieved during testing. Whether this level predicts future CV outcomes is not known.

METHOD: Maximal exercise stress echocardiography was performed on 196 patients with prior treated CV disease for the assessment of returning to commercial vehicle operation. Patients were followed for 5.8±2.4 years with future CV events as the outcome variable.

RESULTS

There were 55 patients with a CV event during the census period. No significant differences were found between those with and without a CV event regarding medication use, CV risk factors or TT data. Cox proportional hazards analysis revealed only statin use (HR 0.49 (0.01-0.91); p=0.02) and inability to reach a maximal rate pressure product (MRPP) of 25,020 (HR 2.81 (1.6-5.0); p<0.001) as independent predictors of CV events, with MRPP the only multivariate predictor (HR 2.5 (1.01-6.28); p=0.04).

CONCLUSIONS

Achieving an age-predicted FC ≥90% following maximal TT does not predict CV outcome (p=0.536) in patients with previous CV disease being assessed for commercial vehicle operation. Inability to reach an MRPP of 25,020 was a strong predictor of future CV events.