Background: A hypertensive response to exercise (HRE; defined as normal clinic blood pressure [BP] and exercise BP >210/105mmHg in men or >190/105mmHg in women) independently predicts incident hypertension and cardiovascular mortality. The mechanisms remain unclear but may be related to masked hypertension. This study aimed to assess the prevalence of masked hypertension and cardiovascular risk factors, including aortic reservoir function, in patients with a HRE.

Methods: Comprehensive clinical and echocardiographic evaluation (including central BP, aortic reservoir pressure, aortic pulse wave velocity by tonometry) and 24 hour ambulatory BP monitoring (ABPM) were performed in 81 untreated patients with HRE (aged 54±9 years; 60% male; free from coronary artery disease). Masked hypertension was defined as ABPM systolic BP (SBP) ≥130 mmHg and clinic BP <140/90 mmHg.

Results: Masked hypertension was present in 50 patients (62%). These patients had higher left ventricular (LV) mass index (92.1±17.8 g/m² versus 77.2±17.9g/m²; p=0.01) aortic reservoir pressure (104±9mmHg versus 97±10mmHg; p=0.001) and exercise SBP (226±15mmHg versus 210+15mmHg; p<0.001), despite no significant difference in aortic pulse wave velocity or central pulse pressure (p>0.05 for both). Aortic reservoir pressure was significantly correlated with peak exercise SBP (r=0.34; p=0.002). The strongest independent determinant of LV mass index was the pressure of masked hypertension (β=0.37; p=0.001) ,

Conclusions: Aortic reservoir pressure is significantly elevated, and masked hypertension highly prevalent in HRE patients with a normal resting office BP. This may help to explain increased risk in patients with a HRE and clinicians should suspect masked hypertension in this population.