Patients with resistant hypertension are 50% more likely to suffer cardiovascular events than patients whose hypertension is not resistant to treatment, a recent study published in Circulation has found.

The retrospective cohort study from the United States included 205,750 patients started on treatment for hypertension between 2002 and 2006.

Patients were followed up for the development of resistant hypertension and subsequent cardiovascular events (death or myocardial infarction, heart failure, stroke or chronic kidney disease). Data were collected on blood pressure measurement and prescription filling information.

Patients with resistant hypertension were defined as those whose blood pressure was not controlled despite the use of at least three antihypertensive drugs.

The results were adjusted for patient and clinical characteristics. Patients who failed to adhere to therapy were excluded.

Overall, 1.9% of patients developed resistant hypertension within a median 1.5 years from initial treatment (0.7 cases per 100 person-years of follow-up).

Patients who developed resistant hypertension were more likely to be male, older, and have higher rates of diabetes compared with non-resistant patients.

Over 3.8 years of median follow-up, cardiovascular event rates were significantly higher in those with resistant hypertension, unadjusted rates: 18.0% vs 13.5% (p < 0.001).

After adjusting for patient and clinical characteristics, resistant hypertension was still associated with a significantly higher risk of cardiovascular events, hazard ratio 1.47 (95% CI: 1.33-1.62).

Most GPs will be challenged by patients with resistant hypertension who despite our best efforts will fail to reach target blood pressure. According to the findings of this study around 1 in 50 newly diagnosed patients with hypertension will go on to develop resistant hypertension.

Furthermore, these patients will have a substantially increased risk of cardiovascular events, 50% greater than patients with non-resistant hypertension. This fact alone should inform our ongoing endeavors to reduce blood pressure in this group despite escalating polypharmacy.

The mechanism behind resistant hypertension is likely to be a little more elusive although a more central role for aldosterone in these patients has been postulated with guidelines supporting the use of spironolactone as add-on therapy in such cases.

Dr Peter Savill

• Daugherty SL, Powers D, Magid DJ et al. Incidence and prognosis of resistant hypertension in hypertensive patients. Circulation 2012; 125(13):1635-42