Comparative Effect of Losartan and Atenolol on Heart Rate Variability in Untreated Essential Hypertensive Patients by Power Spectral Analysis.

ABSTRACT

Autonomic balance in untreated essential hypertension is altered and antihypertensive drugs may improve autonomic balance. Losartan and atenolol is drug of choice to treat essential hypertension. Power spectral analysis of Heart Rate Variability (HRV) is a tool for detecting autonomic balance. This study aimed to compare the effect of losartan and atenolol on autonomic balance in essential hypertensive patients. This longitudinal study was conducted in the Department of Physiology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, Bangladesh from July 2012 to June 2013. For this study, 120 diagnosed male hypertensive patients without any treatment (age 30-55 years) were selected from the Out Patients Department of Cardiology, BSMMU, Dhaka on their first day of visit. Sixty apparently healthy normotensive male subjects with similar age were also studied as control. Patients were divided into two equal groups. Sixty (60) patients received 50 mg losartan (oral) and 60 patients received 50 mg atenolol (oral) daily. Autonomic balance was assessed by power spectral analysis of HRV and HRV data were recorded by a polyrite D. HRV data of the patients were measured at baseline, after 3 months and 6 months of medication and data of control were recorded at baseline. For statistical analysis ANOVA, independent sample 't' test and paired sample 't' were performed. High frequency normalized units (HF n.u), total power (TP) were significantly lower (p<0.001) and low frequency normalized unit (LF n.u), LF/HF ratio were significantly higher (p<0.001) in all patients before treatment compared to control. In both drug groups HF n.u and total power were found significantly higher (p<0.001) whereas LF n.u and LF/HF ratio were found significantly lower (p<0.001) after 3 months of treatment compared to their baseline values. After 6 months of treatment, data demonstrated significant further increase (p<0.001) in HF n.u and total power compared to their values after 3 months of treatment. Again these values were found significantly higher in atenolol treated patients compared to losartan group at the end of 6 months of treatment. These result concluded that cardiac autonomic nerve functions may be impaired in essential hypertensive patients before treatment which may improve by treatment with both drugs but the effect is more pronounced in atenolol treatment after longer duration.