Masked hypertension is “unmasked” by low-intensity exercise blood pressure

Abstract

Purpose: Masked hypertension (MH) independently predicts mortality but cannot be diagnosed from clinic blood pressure (BP) taken under resting conditions. We sought to determine if MH could be identified from BP taken during a single bout of low-intensity exercise. Methods. BP was recorded at rest and during brief low-level cycling exercise (60–70% of age-predicted maximal heart rate) in 75 untreated subjects with a hypertensive response to exercise (aged 54 ± 9 years). All subjects underwent 24-h ambulatory BP monitoring (ABPM) and MH was defined as clinic BP < 140/90 mmHg and ABPM BP ≥ 130/80 mmHg. Results. There were 42 (56%) patients with MH, and at rest systolic (SBP) was higher in subjects with MH compared with those without MH (127 ± 9 vs 120 ± 9 mmHg; p < 0.05). During exercise, MH subjects had significantly higher SBP (188 ± 22 vs 168 ± 15 mmHg; p < 0.05), with a greater change from baseline (61 ± 21 vs 48 ± 15 mmHg; p < 0.05). Low-level exercise SBP was independently associated with MH, and if ≥175 mmHg, identified MH with 74% sensitivity and 67% specificity (p < 0.001). Conclusion. MH can be identified in untreated individuals from low-intensity exercise SBP. Further research on the diagnostic value of BP during early phases of exercise stress testing is needed.

Key Words::

• Blood pressure
• exercise
• hypertension
• masked hypertension

Acknowledgments

In part by a National Health and Medical Research Council project grant (reference 569669), Canberra, Australia. Dr Sharman was supported by a National Health and Medical Research Council Career Development Award (reference 569519). Dr Hare was supported by a scholarship co-funded by the National Heart Foundation of Australia (PC 07B 3407) and the National Health and Medical Research Council of Australia (reference 511266).

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.