Exercise blood pressure, cardiorespiratory fitness and mortality risk

Objective: To assess the cardiorespiratory fitness (CRF) impact on the association between exercise blood pressure (BP) and mortality risk. Patients and methods: We assessed CRF in 15,004 US Veterans (mean age 57.5 +/- 11.2 years) who completed a standardized treadmill test between January 1, 1988 and July 28, 2017 and had no evidence of ischemia. They were classified as Unfit or Fit according to the age-specific metabolic equivalents (METs) achieved <50% (6.2 +/- 1.6 METs; n = 8440) or >= 50% (10.5 +/- 2.4 METs; n = 6264). To account for the impact of resting systolic BP (SBP) on outcomes, we calculated the difference (Peak SBP-Resting SBP) and termed it SBP-Reserve. We noted a significant increase in mortality associated with SBP-Reserve <_52 mmHg and stratified the cohort accordingly (SBP-Reserve <_52 mmHg and > 52 mmHg). We applied multivariable Cox models to estimate hazard ratios (HR) and 95% confidence interval (CIs) for outcomes. Results: Mortality risk was significantly elevated only in Unfit individuals with SBP-Reserve <_52 mmHg compared to those with SBP-Reserve >52 mmHg (HR = 1.35; CI: 1.24-1.46; P < 0.001). We then assessed the CRF and SBPReserve interaction on mortality risk with Fit individuals with SBP-Reserve >52 mmHg serving as the referent. Mortality risk was 92% higher (HR = 1.92%; 95% CI: 1.77-2.09; P < 0.001) in Unfit individuals with SBPReserve <_52 mmHg and 47% higher (HR = 1.47; 95% CI: 1.33-1.62; P < 0.001) in those with SBP-Reserve >52 mmHg. Conclusion: Low CRF was associated with increased mortality risk regardless of peak exercise SBP. The risk was substantially higher in individuals unable to augment their exercise SBP >52 mmHg beyond resting levels. (c) 2021 Published by Elsevier Inc.

Automated summary

This study assessed the impact of cardiorespiratory fitness on the association between exercise blood pressure and mortality risk, finding that individuals with low cardiorespiratory fitness had significantly higher mortality risk when SBP-Reserve <_52 mmHg. The risk of mortality was even higher in individuals who were unable to increase their exercise SBP above resting levels.