title: Do losartan and atenolol have differential effects on BNP and central haemodynamic parameters?
abstract: BACKGROUND
  It has been suggested that angiotensin-converting enzyme inhibitors (ACE-Is) and angiotensin II receptor blockers (ARBs) have a differential effect on brachial and aortic haemodynamics. This is why they seem to have beneficial effects that are beyond brachial blood pressure (BP) lowering. We aimed to investigate if this was the case with losartan when compared to atenolol. We also investigated the differential effect of losartan and atenolol on the prognostic marker, brain type natriuretic peptide (BNP).
  
  
  METHODS
  We studied 17 patients who were similar to those in the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study. Patients were randomised to receive four months of losartan and atenolol in a crossover fashion. Main outcome measures were BNP and Augmentation index (AIx), which gives an indication of central haemodynamics. Brachial pulse wave velocity (PWV) and time to reflected wave (Tr) were measured as an indication of vascular stiffness.
  
  
  RESULTS
  BNP was significantly lower on losartan than atenolol (p=0.007). AIx was lower on losartan than atenolol (p=0.03), however, this result was not significant when heart rate was considered as a covariate (p=0.09). Heart rate was significantly lower on atenolol than losartan (p=0.03). There was no difference between treatments for both brachial PWV and Tr (p=0.2 and p=0.99, respectively).
  
  
  CONCLUSIONS
  The benefits seen when losartan was compared to atenolol in the LIFE trial may be due to a reduction in BNP. We failed to detect a differential effect in central compared to peripheral haemodynamics when losartan was compared to atenolol.
authors.affiliation: Division of Medicine and Therapeutics, Ninewells Hospital and Medical School, Dundee, DD1 9SY, UK. j.i.davies@dundee.ac.uk
authors.forename: Justine
authors.initials: J
authors.lastname: Davies
authors.forename: Elaine
authors.initials: E
authors.lastname: Carr
authors.forename: Margaret
authors.initials: M
authors.lastname: Band
authors.forename: Andrew
authors.initials: A
authors.lastname: Morris
authors.forename: Allan
authors.initials: A
authors.lastname: Struthers
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000627:therapeutic use*; D000959:Antihypertensive Agents / Q000627:therapeutic use; D001262:Atenolol / Q000627:therapeutic use*; D001794:Blood Pressure / Q000187:drug effects; D018592:Cross-Over Studies; D004311:Double-Blind Method; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D006973:Hypertension / Q000188:drug therapy; D019808:Losartan / Q000627:therapeutic use*
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D000959:Antihypertensive Agents; D001262:Atenolol; D019808:Losartan