Secondary causes and renal outcomes in apparently resistant hypertension: a retrospective cohort study

Objective In this study, we aimed to determine the prevalence and spectrum of secondary hypertension among patients with apparently resistant arterial hypertension (aRH) and to compare the rate of decline in estimated glomerular filtration rate (eGFR) between those with primary aldosteronism (PA) and true resistant arterial hypertension (RAH).Methods We conducted a retrospective cohort study of 790 patients with aRH referred to a hypertension excellence center. All patients fulfilled pharmacological criteria for aRH and underwent a screening protocol to evaluate secondary hypertension. We compared clinical and laboratory markers of patients with PA to those with RAH, with a median follow-up of 7 years.Results Secondary hypertension was identified in 213 patients (27%), with PA being the most common cause (17%), followed by renovascular hypertension (4.1%), renal parenchymal disease (3.7%), pheochromocytoma (0.8%), and Cushing’s syndrome (0.6%). Compared to RAH patients, those with PA had significantly fewer cardiovascular comorbidities, lower serum potassium levels (4.13 vs. 4.23 mmol/L). Notably, patients with RAH exhibited a faster decline in renal function, specifically an additional 0.7 mL/min/1.73m2 reduction per year (95% CI 0.05 - 1.35, p = 0.03), despite similar baseline eGFR and BP control. In RAH, a continuous association between higher average 24-hour systolic BP and a faster decline in renal function was observed.Conclusion Systematic screening in aRH reveals a high prevalence of secondary hypertension, particularly PA. Patients with RAH showed significantly worse renal outcomes compared to those with PA, with faster renal decline associated with higher blood pressure within the RAH group, underscoring the need for early diagnosis and strict BP management.