Clinical Trial: Effect of Beta Blockade on Left Ventricular Remodeling and Function in Moderate to Severe Asymptomatic Aortic Regurgitation
Study Status: Completed
Recruit Status: Completed
Study Type: Interventional
Official Title: Effect of Beta Blockade on Left Ventricular Remodeling and Function in Moderate to Severe Asymptomatic Aortic Regurgitation
Brief Summary: The primary objective of this study is to evaluate the effect of beta-blocker on left ventricular (LV) remodeling in asymptomatic patients with moderate to severe aortic regurgitation.
Detailed Summary:
The left ventricle responds to the volume load of chronic aortic regurgitation (AR) with a series of compensatory mechanisms, including an increase in end-diastolic volume, an increase in chamber compliance that accommodates the increased volume without an increase in filling pressures, and a combination of eccentric and concentric hypertrophy. The greater diastolic volume permits the ventricle to eject a large total stroke volume to maintain forward stroke volume in the normal range. This is accomplished through rearrangement of myocardial fibers with the addition of new sarcomeres and development of eccentric LV hypertrophy. As a consequence left ventricular ejection fraction will remain in the normal range.
The clinical course of chronic aortic regurgitation is characterized by a prolonged phase of stability during which the left ventricle adapts to the volume overload. Eventually myocardial failure ensues through a series of complex events that include changes in myocyte phenotype due to re-expression of fetal genes, cellular apoptosis alteration in the expression and function of contractile proteins and changes in the extracellular matrix.
The role of long-term vasodilator therapy in the care of asymptomatic patients with severe aortic regurgitation is controversial. Vasodilator therapy has been used to reduce the regurgitant volume, afterload, left ventricular volumes, and wall stress in an effort to preserve left ventricular function and reduce left ventricular mass. Thus time to surgical intervention has been found to be delayed by calcium antagonists, ACE-inhibitors and hydralazine, while a more recent study did not find any effect of nifedipine or enalapril on time to surgery or left ventricular volume and function.
The decision to recommend operative intervention
Sponsor: Oslo University Hospital
Current Primary Outcome: Left ventricular end-diastolic volume [ Time Frame: 6 months ]
Original Primary Outcome: Same as current
Current Secondary Outcome: Left ventricular end-systolic volume [ Time Frame: 6 months ]
Original Secondary Outcome: Same as current
Information By: Oslo University Hospital
Dates:
Date Received: July 5, 2010
Date Started: August 2010
Date Completion:
Last Updated: September 24, 2014
Last Verified: September 2014
