[Effects of Olmesartan Medoxomil on Patients with Thoracic and Thoracoabdominal Aortic Aneurysm;Evaluation of Anti-hypertensive Effect and Possible Suppression of Aneurysmal Dilation( OLM 40 Study)].

We evaluated the blood pressure( BP) lowering effect and possible suppression of aortic enlargement by olmesartan (OLM) in patients with thoracic and thoracoabdominal aortic aneurysm. In this single center prospective, forced titration study, 50 patients were registered between 2008 and 2011. After all patients received any of OLM 10, 20, and 40 mg/day as an initial dose, the dosage of OLM was titrated up to 40 mg as needed during follow-up period. Home BP (HBPs), aortic aneurysm size assessed by computed tomography (CT) scan, indices of renal function were recorded at 3- and 6-months follow-up. Depending on whether 40 mg/day of prescription was continued for more than 4 months or not, the patients were divided into 2 groups:less than 40 mg (<40 mg) and 40 mg groups. Morning HBPs tended to decrease in both groups, and the percent changes in BPs were essentially the same regardless of dosage. The absolute value of aortic diameter tended to slightly enlarge only in <40 mg group. Also in the <40 mg group, the absolute differences in aortic diameter between those at the time of study registration and each follow-up were 0.5±1.8 mm at 3-month and 1.2±2.3 mm at 6-month (p=0.047),whereas the percent changes were 0.9±3.3% and 2.2±4.5% at 3 and 6 months, respectively( p=0.058). As for 40 mg group, the absolute differences and percent changes did not reach statistically significant increase during the follow-up period. No severe renal dysfunction related to OLM 40 mg prescription was observed. Our results imply that OLM 40 mg may suppress aortic aneurysmal dilation independently of blood pressure lowering effect. Further study with larger number of sample size is warranted to assure this observation.