Design and methods
HTN, hypertension, kidney dysfunction
HTN, KIDNEY DYSFUNCTION, SECONDARY, -11, HYPERTENSION
In an open prospective single-center study, we included patients with suspected resistant HTN referred to the center at Almazov National Medical Research Center (St Petersburg, Russia) which is recognized as one of the ESH hypertension excellence centers. These patients were recruited for endovascular radiofrequency RDN in 2012–2019 as per inclusion/non-inclusion criteria.Inclusion criteria were: age 20–65 years old; BP ≥ 140/90 mmHg despite regular intake of at least 3 antihypertensive drugs in appropriate doses including a diuretic, and informed consent.Non-inclusion criteria were: secondary endocrine HTN; severe kidney dysfunction (estimated glomerular filtration rate (eGFR) < 45 ml/min/1.73mAmong 70 patients who underwent RDN, 41 patients had valid baseline sleep study, while 28 patients had both baseline and follow-up sleep studies (Fig. 
Study flow chartThe study was performed in accordance with the principles of Good Clinical Practice and 2013 Declaration of Helsinki. The study protocol was approved by the Scientific Council of Almazov National Medical Research Centre on 23.12.2011 (protocol №11), and later the updated version of the protocol was approved in 2018 by the Local Ethics Committee of Almazov National Medical Research Centre (protocol №2018-12-11). All patients signed informed consent before the enrollment in the study.