Myocardial Efficiency of the Left Ventricle in Asymptomatic Patients With Aortic Valve Stenosis - a Prognostic Marker and a Target for Intervention?

Overview

Background - Aortic valve stenosis (AS) is the most common heart valve disease among adults in the Western world with a prevalence of 3 % in people older than 75 years of age. AS usually deteriorates over time leading to heart failure, with high mortality if aortic valve replacement (AVR) is not performed. Thus optimal timing of AVR is crucial, but can be challenging. Increasing life expectancy in our society will augment the therapeutic and socio economic impact of AS disease on our health care system. Therefore, new techniques for monitoring asymptomatic AS patients are needed. A potential approach is monitoring of LV myocardial efficiency (mechanical work/oxygen consumption). These measures have been suggested to be involved in the progression of non-valvular heart failure and closely related to prognosis, but never applied in a larger population of patients with AS. At present there are no recognized pharmacological treatments of AS. It is known that beta-blocker treatment in non-valvular systolic heart failure reduce heart rate, improves LV myocardial efficiency and reduces mortality. However, in patients with AS, the effects of beta-blockers are unknown. Hypotheses - Treatment with the beta-blocker metoprolol succinate in patients with asymptomatic moderate to severe AS has beneficial effects on LV myocardial oxidative metabolism, myocardial efficiency and contractile function. Objectives - To investigate if beta-blocker treatment in patients with moderate to severe, asymptomatic AS has beneficial effects on LV myocardial efficiency, contractile function and physical performance. Design - A randomized double blind placebo controlled intervention trial. 40 patients with asymptomatic AS will be randomized to either per oral metoprolol succinate (N = 20) or placebo (N= 20) for 22 weeks. Primary objective - Changes in myocardial efficiency Secondary objectives - Myocardial oxygen consumption, Myocardial perfusion at rest, LV myocardial function, LVmass, Aortic valve area and transaortic valve velocities, 6 minute walking distance, N-terminal prohormone of brain natriuretic peptide, Quality of life (estimated by Minnesota living with heart failure questionnaire), LV wall stress Methods - Patients will undergo echocardiography (resting and exercise), \[11C\]acetate PET and cardiac magnetic resonance imaging.