Comparative prognostic value of absolute and fitness-adjusted exercise systolic blood pressure for mortality: a prospective cohort study

Abstract Background An exaggerated systolic blood pressure (SBP) response during exercise is a recognized marker of increased cardiovascular risk. However, existing evidence remains inconsistent, and it is unclear whether submaximal or peak SBP provides greater predictive value for mortality. Moreover, it is unclear whether adjusting SBP for cardiorespiratory fitness (VO2max) enhances the clinical interpretation of exercise induced SBP responses. Purpose This study aimed to assess whether fitness-adjusted SBP indices at submaximal or peak exercise levels offer superior prognostic value for mortality compared to their absolute counterparts. Methods We analyzed data from 2,410 adults aged 42–61 years who were enrolled in the Kuopio Ischaemic Heart Disease Study cohort. All participants completed cardiopulmonary exercise testing with direct measurement of VO2max. Systolic blood pressure (SBP) during exercise testing was recorded at both submaximal workload (4 minutes into exercise) and at peak exercise. Fitness-adjusted SBP indices were calculated by dividing SBP by VO2max and expressed in mmHg/ml·kg−¹·min−¹. The outcomes were all-cause and cardiovascular mortality over a median follow-up period of 26 years. Results Higher submaximal SBP and submaximal SBP/VO2max indices were significantly associated with increased risks of both all-cause and cardiovascular mortality. Each 1-standard deviation increase in the submaximal SBP/VO2max index was associated with a 28% greater risk of all-cause mortality (HR 1.28, 95% CI 1.20–1.37) and cardiovascular mortality (HR 1.28, 95% CI 1.16–1.41). In contrast, peak SBP showed no significant association with either outcome. Among all exercise blood pressure metrics, the submaximal SBP/VO2max index demonstrated the greatest discriminative ability for predicting cardiovascular mortality (AUC = 0.664), outperforming both absolute SBP values and peak SBP/VO2max. Conclusions A submaximal, fitness-adjusted SBP index provides superior long-term prognostic value for all-cause and cardiovascular mortality compared to absolute SBP measures or peak exercise responses. These findings highlight the clinical utility of incorporating cardiorespiratory fitness–adjusted SBP metrics during submaximal exercise into routine assessment protocols to enhance cardiovascular risk stratification and guide preventive strategies.