Safety and Efficacy of Angiotensin Receptor Blocker, Fimasartan, on Patients With Aortic Stenosis

Aortic stenosis (AS) is common valvular disorder, affecting 2% to 4% of adults older than 65 years. It is gradually but constantly progressive disease whit a long asymptomatic phase, but once symptoms develop, the prognosis is poor.

Currently, treatment strategy is focused mainly to watchful monitoring and judicious timing of aortic valve replacement (AVR). However, not all patients are proper candidate of corrective surgery and the needs of development of medical treatment are increasing. Various mechanisms have been suggested in progression of AS and recent observational studies suggested not only mechanical stress of "wear and tear" but also active inflammatory process likewise atherosclerosis may contribute the progression of AS. Through clinical descriptive studies, atherosclerotic risk factors, such as hypertension, diabetes mellitus, dyslipidemia, obesity, smoking, and metabolic syndrome have been known to facilitate the progression of AS.

The renin-angiotensin system (RAS) is activated at an early stage of AS, promoting developemtnt of left ventricular hypertrophy (LVH), myocardial fibrosis, and diastolic dysfunction. Lipid lowering therapy and RAS blockade have emerged potential medical treatment to slow the progression of AS, however, many clinical trials did not show consistent beneficial effect of statins.8-10 RAS blockers are perceived as being relative contraindication due to concerns about increasing pressure gradient. However, patients with AS tolerate RAS blocker well on initiation and the use of angiotensin converting enzyme (ACE) inhibitors appears to confer long term survival benefit on patients considered to have a contraindication including AS.Pressure overload of LV, activation of RAS, and subsequent adverse LV remodeling, myocardial fibrosis, and LV dysfunction may potential therapeutic target to retard the progression of AS and to improve exercise capacity, and even long-term outcomes. RAS blocker including ACEI or angiotensin receptor blockers (ARBs) have been known to improve exercise capacity and long term outcome in patient with hypertension, congestive heart failure, or myocardial infarction.

We hypothesized that fimasartan, a new generation ARBs, would improve exercise capacity and decrease the rate of progression of AS by modifying hemodynamic factors and reducing adverse LV remodeling favorably in patients with asymptomatic moderate to severe AS.

Prospective, double-blinded, randomized clinical trial with enrollment of normotensive or hypertensive patients of age 20 to 75 who require echocardiography for a clinical indication, which typically consists of known aortic stenosis or presence of cardiac murmur. Moderate to severe aortic stenosis will be defined as a continuous wave Doppler determined peak aortic valve jet velocity of 3.0 - 4.5 m/s or mean pressure gradient of 25 - 49 mmHg, or aortic valve area of 0.76 - 1.5 cm2. Patients meeting inclusion criteria without any exclusion criteria will be randomized 1:1 to angiotensin receptor blocker, Fimasartan, or placebo. After 1-year enrollment period, all patients will be followed for 1 year. Cardiopulmonary exercise test will be performed at baseline enrollment period, and at the end of follow-up. Echocardiographic evaluation will be performed at regular interval of baseline and 6 months interval until the end of study.