The relationship between higher blood pressure readings and increased incidence of cardiovascular events and target organ damage, has been well established in multiple large cohort studies.

Hypertension in the UK is defined as a clinic reading exceeding 140/90 or a home reading over 135/85.

White Coat Hypertension [WCH] – when blood pressure readings are raised over 140/90 in clinic, but within the normal range when measured at home – is common and seen in up to 20% of people.

Questions to consider about WCH are:

• Is WCH benign or do these patients have an adverse prognosis?
• What complications can occur in patients with WCH?
• Does treatment have an impact on prognosis?

Patients with WCH have a three-fold risk of developing sustained hypertension.

The association between WCH and cardiovascular events is less clear; with some studies suggesting the risk lying somewhere between normotensive and sustained hypertension and others, that there is no additional risk.

For patients with uncomplicated WCH [without other risk factors], lifestyle changes, together with regular monitoring may be the only interventions needed.

Lifestyle changes:

• Regular exercise
• Weight loss
• Reducing salt intake
• Stopping smoking
• Reducing alcohol and caffeine intake

Regular Monitoring:

There are 3 measures considered when evaluating WCH:
1.    BP recording in a clinical setting by a health care professional.
2.    BP recording at home by the patient.
3.    24-hour ambulatory BP recording [not just daytime ambulatory monitoring as nocturnal hypertension is a better predictor for future adverse events].

Those whose blood pressures are normal for all 3 are normotensive [NH]. Those with an elevated clinic BP but normal for either home or ambulatory have white coat hypertension [WCH].

There are patients who have normal BP readings in clinic but have raised BP recordings elsewhere [home or ambulatory] and this group are said to have masked hypertension [MH]. For the purposes of this article, patients with WCH and MH are regarded as having the same attendant risks.

Complications:

Observations from the PAMELA study suggested that, over a period of 10 years, the risk of transitioning from normotensive to sustained hypertensive was 2.5-fold greater in those with WCH compared to normotensives. Based on this observation, it could be argued that patients with WCH could be viewed as ‘pre-hypertensives’.

While myocardial infarction and stroke are the main clinical manifestations of hypertensive disease, there is evidence of organ damage in a graded way with WCH. Analysis of pooled data from meta-analysis shows that left ventricular mass increases from normotensives, higher in WCH and highest in sustained hypertensives.

This gradation remains when other markers, such as left atrial diameter and carotid intimal thickness [a risk factor for stroke] are examined.

The conclusion is that WCH is an intermediate risk factor between normal BP and hypertension.

Should it be treated?

Data is limited.

Patients with untreated WCH have a significant risk of transitioning to sustained hypertension and have evidence of cardiac and vessel changes greater than normotensives.

From the available randomised controlled trials [RCTs], the findings are that treating WCH to target level, reduces the risk of cardiovascular events to normotensive levels.

Conclusions

• Don’t ignore WCH.
• It is an intermediate risk factor.
• For those with associated cardiovascular risks – diabetes, smokers, high BMI, previous cardiovascular events – it is a significant association, and look for appropriate treatment and evidence of treatment to target level.

Author: Dr Debesh Mukherjee, FRCP Company Medical Advisers Ltd.
Contact: Admin@companymedicaladvisers.co.uk
 

Last updated: 03/10/2024
References: available on request.