Aim of the study is to determine the impact of the COVID-19 pandemic on blood pressure profiles and variability as assessed by ambulatory blood pressure monitoring (ABPM) through the comparison of ABPM data obtained before and during the COVID-19 lockdown in already treated hypertensive patients

Recruitment for the study will be conducted according to the principles outlined in the Helsinki declaration for investigations in human subjects. The Ethics Committee of each Center must approve the protocol. We will collect clinical data, including office and ambulatory blood pressure of patients with treated arterial hypertension at least 18 years of age.

The study will include two different groups . Group 1 - will constitute of participants with two repeated ABPM recordings (visits): the second visit performed between 01.04.2020 - 31.03.2021 (i.e., during the COVID-19 pandemic announced by the WHO in 11.03.2020) and the first visit 9-15 months before the second ABPM recording, but not later than 31.12.2019.

Group 2 - will constitute of participants with two repeated ABPM recordings (visits) - both visits performed before the pandemic: the second visit in 01.01.2019 - 31.12.2019 and the first visit 9-15 months before the second.

Primary outcome. Difference of changes (deltas) in averaged 24-hour systolic and diastolic BP assessed by ABPM from Visit 1 to Visit 2 between Group 1 and Group 2.

Primary outcome evaluation:

1. Assessment of BP (i.e., average 24hSBP, average 24hDBP) changes (deltas) from values recorded in the year preceding the COVID-19 pandemic to BP (i.e., average 24hSBP, average 24hDBP) values measured during the lockdown (Group 1).
2. Assessment of BP (i.e., average 24hSBP, average 24hDBP) changes (deltas) from values recorded in the pre-pandemic period with 9-15 months' time interval (Group 2).
3. Differences in BP (i.e., average 24hSBP, average 24hDBP) changes (deltas) assessed by ABPM from Visit 1 to Visit 2 between Group 1 and Group 2.

Secondary outcomes:

1. Assessment of BP (i.e., average 24hSBP, average 24hDBP) changes predictors in Group 1 and Group 2.
2. Assessment of differences in averaged Daytime (awake) BP changes assessed by ABPM from Visit 1 to Visit 2 between Group 1 and Group 2.
3. Assessment of differences in averaged Night-time (asleep) BP changes assessed by ABPM from Visit 1 to Visit 2 between Group 1 and Group 2.
4. Assessment of white - coat, masked, and resistant hypertension prevalence in Group 1 and Group 2.
5. Assessment of the extent of asleep BP fall, and dipper/non-dipper phenotypes prevalence in Group 1 and Group 2.
6. Analyses of BP short-term (24hABPM) variability

Inclusion Criteria:

1. Pharmacologically treated hypertensive patients.
2. Office systolic, diastolic blood pressure and heart rate available from the day (+/- 1 month) of ABPM recording. If office BP are not available, please provide first BP measurement from ABPM recording.
3. Availability of at least two valid ABPM recordings in 9-15 months interval. a. Group 1 with the second ABPM during the pandemic period: i. First ABPM (visit 1) obtained 9-15 months before the second ABPM recording, but not later than 31.12.2019 ii. Second ABPM (visit 2) obtained during the pandemic period 01.04.2020 - 31.03.2021 b. Group 2 with both ABPM recordings before the pandemic period: i. First ABPM (visit 1) obtained 9-15 months before the Second ABPM ii. Second ABPM (visit 2) obtained between 01.01.2019 - 31.12.2019

Exclusion Criteria:

1. Confirmed secondary hypertension.
2. Hypertension in pregnancy.
3. Device based treatment of hypertension.
4. Development of heart failure, cardiac surgery, myocardial infarction, or cancer between ABPM measurements.
5. Parkinson disease.
6. Alcohol or drug abuse.

We will collect clinical data, including office and ambulatory blood pressure of patients with treated arterial hypertension at least 18 years of age