Exercise blood pressure in adults with high-risk left ventricular hypertrophy: the importance of normalizing blood pressure to oxygen uptake.

Abstract

Introduction: Exaggerated exercise blood pressure (EEBP) is typically defined using systolic blood pressure (SBP) thresholds at maximal exercise of ≥190 (women) and ≥210 mmHg (men). However, SBP/workload and SBP/oxygen uptake (V̇O2) slopes have been shown to be more sensitive predictors of all-cause mortality and/or cardiovascular morbidity than peak exercise SBP. Hypertensive adults with left ventricular hypertrophy (LVH) often present with EEBP; whether the change in SBP with exercise is also greater when normalized for workload/V̇O2 is unknown. Therefore, we compared absolute and normalized exercise SBP in adults with LVH and age-matched healthy controls.

Methods: We measured BP (brachial electrosphygmomanometry) and V̇O2 (indirect calorimetry) during treadmill exercise in middle-aged adults who were either healthy (n = 52) or had LVH and elevated cardiac biomarkers (n = 48). Data were compared using Welch's t-tests and Fisher's exact tests.

Results: Absolute V̇O2 max was not different between groups (LVH: 2.24 ± 0.61 vs. Healthy: 2.21 ± 0.69 l/min, P = 0.862). Baseline (P < 0.001) and max SBP were higher in LVH (196 ± 25 vs. 173 ± 26 mmHg, P < 0.001); as such EEBP incidence was higher in LVH (48 vs. 11%, P < 0.001) when measured using the SBP thresholds. However, there was no difference in the change in SBP from rest (P = 0.174) nor the SBP/V̇O2 slope between groups (LVH: 37 ± 18 vs. Healthy: 33 ± 17 mmHg/l/min, P = 0.334).

Conclusion: The greater EEBP incidence in LVH using traditional thresholds reflects differences in resting BP, not an exaggerated SBP response. Therefore, those with high-risk LVH have a normal SBP response to exercise despite achieving a higher max SBP for the same absolute V̇O2 max.