Effect of Losartan and Atenolol on heart rate variability in newly diagnosed essential hypertensive patient
Background: Essential hypertension is associated with altered autonomic function. Essential hypertension is treated with drugs which modify the sympatho-parasympathetic balance. Losartan (angioteosin II receptor blocker) and atenolol (beta blocker) is commonly used antihypertensive drugs.
Objective: To evaluate the effect of antihypertensive drugs on heart rate variability (HRV) in patients with essential hypertension.
Methods: This prospective observational study was carried out in the Department of Physiology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Shahbag, Dhaka from July 2012 to June 2013 on 120 newly diagnosed hypertensive patients without any medication (group B, age 30-55 years). They were selected from the Out Patients Department (OPD) of cardiology, BSMMU, Dhaka. Age, sex and BMI matched 60 apparently healthy norrnotensive subjects were also studied as control (group A). Based on treatment, these study subjects were divided into two groups (BI and B2). Group B1a included 60 patients received Josartan 50 mg daily and B2a included 60 patients received atenolol 50mg daily. They were observed once before the treatment (B1a & B2a), after 3 months medication (B1b & B2b) and after 6 months medication (B1c & B2c). For assessing HRV, Mean heart rate, Mean R-R interval, Max/Min R-R interval, SDNN, RMSSD were recorded by a polyrite. Data were compared among before treatment, after 3 months treatment and after 6 months treatment. For statistical analysis ANOVA, independent sample't' test and paired sample 't' test were performed.
Results: Mean resting pulse rate, mean heart rate, systolic blood pressure, diastolic blood pressure were significantly higher and mean R-R interval, Max/Min R-R interval, SDNN, RMSSD were significantly lower in newly diagnosed hypertensive patients in comparison with that of healthy normotensive subjects and after treatment. Jn both groups SDNN, RMS SD, mean R-R interval were found significantly higher after 6 months of treatment compared to their values after 3 months treatment. Again these values were found close to the values in normotensive subjects. In addition, mean heart rate was found significantly lower in atenolol treated patients than those of controls. Again in atenolol group these values were found significanLly higher than the corresponding values in losartan treated patients after 6 months treatment.
Conclusion: Reduced cardiac vagal tone occurs in newly diagnosed hypertensive patients which is improved by both losartan and atenolol and in particular atenolol was found more effective.