Unmasking masked hypertension with exercise blood pressure (The UNMASKED BP Study)
Masked hypertension (MH) is defined as normal measured clinic blood pressure (BP) with raised BP at other times outside of the office (i.e. measured using 24 hour ambulatory BP). This is an insidious condition as doctors believe that an individual has normal BP on the basis of clinic readings, when in fact they have uncontrolled hypertension (hence 'masked' hypertension). Owing to this 'masking,' individuals remain undiagnosed, untreated and, therefore, at substantially increased risk for serious cardiovascular events and death. In the general population, MH is prevalent (~10%), but patients with type 2 diabetes are especially vulnerable (30% to 47% prevalence). An ongoing clinical dilemma has been to find a better way to identify high risk people with MH.
We have discovered a simple, internationally-applicable and highly cost effective way to identify MH from the mandatory BP recording undertaken during a conventional exercise stress test (EST). Our preliminary pilot work strongly supports the hypothesis that people with normal clinic BP who have an exaggerated BP response during an EST are very likely to have MH. That is, the exercise BP response may serve as a warning signal to doctors regarding the presence of MH.
Each year, more than 400,000 Australians (and many millions worldwide) undertake an EST and we believe the BP information collected during the study will significantly alter the way that many of these people are managed. The UNMASKED BP study will be a world first investigation to definitively test the value of exercise BP for predicting MH in 700 patients undergoing a clinically indicated EST. The findings are expected to change international hypertension management guidelines, improve medical practice regarding identification of high risk individuals and ultimately reduce the community burden relating to cardiovascular disease.