A randomized, double blind pilot study to assess the effects of losartan vs. atenolol on the biophysical properties of the aorta in patients with Marfan and Loeys-Dietz syndromes.

Patients with Marfan (MFS) and Loeys-Dietz (LDS) syndromes have been shown to have abnormal aortic biophysical properties. The purpose of this study was to compare the effects of 12-months of therapy with atenolol or losartan on vascular function in young patients with MFS and LDS. Seventeen patients with MFS or LDS were recruited and randomized to treatment with atenolol, 25-50mg, or losartan, 25mg daily. Prior to treatment and following therapy, echocardiography for left ventricular size, function and aortic root size was performed. Pulse wave velocity (PWV), input (Zi, ZiF) and characteristic (Zc, ZcF) impedances, arterial stiffness (Ep and β-index), total arterial compliance (TAC), mean (Wm) and total (Wt) hydraulic power, efficiency, power cost per unit of forward flow (Wt/CI) and brachial artery flow-mediated dilation (FMD) were measured. The atenolol group consisted of 9 females (17.6years) and the losartan group 7 males and 1 female (17.0years). Their height, weight, BSA, BMI, systolic and diastolic blood pressures were similar. Baseline to 12-month changes for atenolol and losartan were PWV (20% vs -14%), Zi (-2% vs -27%), Zc (-20% vs -27%), Ep (1%, vs -13%), β-index (10% vs 14%), FMD (11% vs 20%), TAC (3% vs 42%), Wm (-24% vs 15%), Wt (-24% vs 17%), and Wt/CI (3% vs 21%). There was a trend for losartan to decrease PWV and stiffness indexes while atenolol decreased power and power/unit flow. This pilot study suggests that atenolol and losartan may have different mechanisms of action on vascular function. A larger clinical trial is needed to confirm these effects.Clinical trials registration NCT00593710 (ClinicalTrials.gov).