Accurate diagnosis, treatment important in resistant hypertension
The prevalence of resistant hypertension may be lower than expected, particularly once pseudo-resistant hypertension due to treatment nonadherence is taken into account, according to a presentation at the recent APCH 2017.
“A key aspect of resistant hypertension is an accurate diagnosis,” said Professor Bryan Williams from University College London and chairperson of the European Society of Cardiology (ESC) Council on Hypertension. This would involve excluding secondary and pseudo-resistant hypertension, he said. [APCH 2017, symposium G]
Patients with pseudo-resistant hypertension include those who may not have accurate blood pressure (BP) measurement (eg, wrong cuff size), those with white coat hypertension, those receiving suboptimal treatment for hypertension, or those who are nonadherent to treatment.
Common causes of secondary hypertension are kidney or renal artery disease, and aldosterone-producing adenomas, while less common causes include Cushing’s syndrome, phaeochromocytoma, and monogenic disorders.
To identify patients with resistant hypertension, it must first be determined if the patient is hypertensive and if yes, if the patient is receiving optimal treatment and adhering to it. Based on the association between a higher number of medications and nonadherence, simplifying the treatment (eg, from multiple pills to one) may help. If none of these are effective, secondary hypertension would need to be ruled out, said Williams.
“True resistant hypertension is uncommon after exclusion of pseudo-resistance and secondary causes,” said Williams, suggesting that the prevalence may be less than 10 percent of all treated hypertensive patients.
Treating resistant hypertension
Lifestyle modification, BP-lowering medication, and devices may help in the management of resistant hypertension, said Williams.
In terms of lifestyle management, high dietary sodium consumption can contribute to resistance to hypertension drugs, he said.
Medication-wise, guidelines published by the ESC in 2013 stressed the use of diuretics in the management of resistant hypertension, particularly low-dose spironolactone. However, the guidelines also highlighted the potential for hyperkalaemia with spironolactone, especially among patients with a low estimated glomerular filtration rate (eGFR), and suggested eplerenone, amiloride, and loop or higher-dose thiazide-type diuretics as alternatives, as well as α- or β-blockers, or centrally acting agents, said Williams. [Eur Heart J 2013;34:2159-2219]
“[The ESC guidelines] emphasized very strongly that all of this is based on observational data or personal opinion, but the evidence base is very low,” he said.
“Resistant hypertension is predominantly a sodium-retaining state that responds best to additional diuretic therapy. In patients with an eGFR >60 mL/min, spironolactone 25–50 mg daily is very effective and generally safe and well tolerated, although gynaecomastia can become a problem in men [with longer term use]. Higher dose amiloride 10–20 mg daily may be an alternative to spironolactone but the same caveats apply regarding renal function and potassium,” said Williams, who underscored the need for further research into determining the potential role of other diuretics in managing resistant hypertension.
He also pointed out the importance of baseline eGFR and potassium levels due to the increased risk of hyperkalaemia in individuals with eGFR <60 mL/min or potassium levels >4.5 mmol/L, and especially in those with eGFR <45 mL/min or with potassium levels >5.0 mmol/L. Aldosterone-producing adenomas are also a possibility in patients who respond very well to spironolactone.
With regards to devices, continuous positive airway pressure or CPAP can be an effective BP-reducing measure if the primary cause of the resistant hypertension is obstructive sleep apnoea, said Williams. Evidence also points to the potential effectiveness of baroreceptor stimulation, though this measure is expensive, requires surgical implantation, and is not well tolerated in some patients, he said.