The European Society of Hypertension defines masked hypertension (MH) as a condition in which a patient's clinic blood pressure (BP) is <140/90 mmHg but home BP readings are in the hypertensive range of >135/85 mmHg.
Masked hypertension can be sub-classified according to the pattern of ambulatory BP and causal mechanisms. The detection of masked hypertension subtypes and their causal mechanisms might have prognostic and therapeutic implications in the long-run. Various subtypes include morning hypertension, daytime hypertension, and night time hypertension. The mechanisms of MH can be divided into two groups: reduced office BP and increased ambulatory BP. The reduced office BP in relation to ambulatory BP is often attributed to a phenomenon of ‘regression-to-mean’, wherein office BP has been consistently lower than ambulatory BP among normotensive patients. The absence of diagnostic labelling may explain lower office BP noted in patients with MH. The factors which selectively augment ambulatory BP include gender (male), alcohol consumption, obesity, smoking, lack of physical activity, and psychosocial factors like anxiety, interpersonal conflicts, and work stress.
The global prevalence of masked hypertension varies from 8 per cent to 15 per cent in various studies. Masked hypertension is becoming an evident clinical entity with insufficiently acknowledged prevalence and increased cardiovascular risk. With the widespread availability of HBPM (Home Blood pressure monitoring) and ABPM (Ambulatory Blood pressure monitoring), more evidence of its detection and prognostic implications is emerging. Patients with MH and sustained hypertension are at equivalent risk for developing cardiovascular (CV) diseases, and a higher risk of CV and stroke mortality and morbidity compared to the normotensive group. These findings suggest that masked hypertension is a serious threat. It is also safe to presume that there will be a significant number of people who are truly hypertensive, but in whom the diagnosis is missed by clinic BP measurement.
Patients with masked hypertension are usually under-treated and are at risk of cardiovascular complications and since its prevalence is high it is necessary to determine its frequency. We also require better means of identifying such individuals by making home and ambulatory BP monitoring a routine. Masked hypertension is a clinical entity which needs to be assessed in the at-risk population.
Practical situations to suspect masked hypertension:
1) Unexplained detection of left ventricular hypertrophy ECHO or microalbuminuria
2) Abnormal retinal arteriosclerosis with normal clinic blood pressure
3) Asymptomatic carotid arteriosclerosis
4) Pre-existing Diabetes or dyslipidaemia
5) Patient with history of event i.e. stroke or MI.
In such situations home blood pressure monitoring (HBPM) & ambulatory blood pressure monitoring (ABPM) are useful to “Unmask the Masked Hypertension”. Once identified, adequate management strategies should be instituted. Masked hypertensive should get timely antihypertensive treatment to prevent cardiovascular morbidity and mortality.
*As per Indian guidelines of hypertension
Disclaimer: The article has been contributed by Dr Kapardhi PLN, Director Cardiac Cathlab, Apollo Hospital Hyderguda Hyderabad. The opinions expressed in this article are the personal opinions of the author. The facts and views appearing in this article do not reflect the views of Deccan Chronicle and Deccan Chronicle does not assume any responsibility and liability for the same.