Patients

We prospectively enrolled 90 patients (50 men and 40 women), aged over 18 years referred to our outpatient cardiology clinic and diagnosed with stage 1 or 2 essential hypertension based on the European Society of Cardiology guidelines (7). Thirty-three age- and sex-matched participants with normal blood pressure who were admitted to our outpatient cardiology clinic with atypical chest pain or palpitation served as the control group. The local Ethics Committee approved the study protocol, and written informed consent was obtained from each participant. At the first visit, each patient underwent a medical evaluation, including clinical history, physical examination, routine blood analysis, lipid profile, electrocardiography, and echocardiography. Blood pressure was measured with an appropriately sized arm cuff and a manual mercury sphygmomanometer after 5 minutes of rest. The same physician performed all measurements, and the mean of two sitting measurements at 2-minute intervals was used. Hypertension was defined as a systolic blood pressure (SBP) ≥140 mm Hg and/or a diastolic blood pressure (DBP) ≥90 mm Hg on repeated measurements. Apelin concentration has been shown to be associated with several conditions, including coronary artery stenosis, diabetes, obesity, aortic stenosis, chronic kidney disease, and heart failure (8–13). Therefore, patients who had a history of coronary artery disease, secondary hypertension, diabetes mellitus, moderate or severe valvular heart disease, body mass index above 30 kg/m², LV ejection fraction <45%, or serum creatinine concentration >1.6 mg/dL were excluded. None of the patients were taking any antihypertensive medication at baseline. Patients diagnosed with essential hypertension were randomly assigned to treatment with either 80 mg telmisartan or 10 mg amlodipine orally once daily. Randomization was performed using a random number table. In addition to routine blood analysis, another blood sample for apelin measurement was obtained from each patient and stored in our laboratory for later analysis.

Thirteen patients were excluded from the final analysis: five were lost to follow-up (three in the amlodipine group and two in the telmisartan group); five stopped treatment due to side effects (three in the amlodipine group and two in the telmisartan group); and three required additional drug therapy to bring blood pressure under control (one in the amlodipine group and two in the telmisartan group).

After 1 month of treatment, patients with hypertension were recalled for echocardiography and blood sampling for measurement of follow-up plasma apelin concentration. Ambulatory blood pressure monitoring was performed to evaluate the effectiveness of antihypertensive therapy using an oscillometric device (Tracker NIBP2, DelMar Reynolds Medical, Morrisville, USA) that recorded blood pressure every 30 minutes during the day and every 45 minutes at night.