Summary

Patients with resistant hypertension do not do well with standard management. But researchers have found that 24-hour blood pressure monitoring could give real benefits for this group. Those with blood pressure raised at night-time were at increased risk of heart attack and stroke. This was a better indicator of risk than blood pressure checked in the doctor's office.

Introduction

Resistant hypertension (RH) is defined as the failure to control blood pressure measured as high in the doctor's office, despite use of as many as three different blood pressure drugs. It can affect up to one third of those with high blood pressure. Naturally, it is worrying because these patients presumably continue to have a risk of cardiovascular disease. Previous research has suggested that 'white coat' hypertension might be a factor in RH. White coat hypertension is a rise in blood pressure occurring in the doctor's office among those who may have normal blood pressure otherwise. In these cases, the white coat effect can be controlled for by offering 24 hour ambulatory blood pressure monitoring. There is a need, however, for more information on how ambulatory blood pressure data relates to actual cardiovascular risk.

What was done

Doctors at the University of Rio de Janeiro, Brazil, studied a group of 556 patients with RH attending their outpatient clinic between 1999 and 2004. They were given 24 hour blood pressure monitoring with readings made every 15 minutes during the day and every 30 minutes at night. They were followed up for around five years.

What was found

During follow-up, 109 participants had a cardiovascular event or died of cardiovascular disease. This included 44 cases of stroke, 21 heart attacks, ten new cases of heart failure and five sudden deaths. Blood pressure measured in the doctor's office did not predict any of these events. Ambulatory blood pressure measurements did, however. Night-time blood pressure was particularly important in predicting cardiovascular risk. If night-time systolic (top figure) blood pressure was increased by 22 millimeters of mercury, the risk of future cardiovascular events was up by 38 percent. If diastolic (bottom figure) blood pressure went up by 14 millimeters of mercury, cardiovascular risk went up by 36 percent.

What this study means

This work highlights the importance of 24 hour ambulatory blood pressure monitoring in the management of RH. Night-time measurements are particularly important in predicting risk. Therapeutic interventions might be best targeted toward trying to reduce blood pressure at night, where possible. This may offer the patient with RH the best chance of reducing cardiovascular risk.