Accelerated 3 D Tagging for Quantification of Left Ventricular Dyssynchrony in Patients after Myocardial Infarction

Introduction: Cardiac resynchronization therapy (CRT) has proved successful in larger patient populations as an adjunctive therapy for patients with drug-refractory heart failure and ventricular conduction delay. However, individual responsiveness to CRT is not yet highly predictable. Around 30% of patients do not appear to benefit from CRT [1]. This can either be attributed to inappropriate patient selection or to suboptimal application of therapy. Accurate quantification of regional motion patterns and left ventricular (LV) dyssynchrony can improve discrimination of CRT responders from non-responders as well as individual responsiveness of patients [2]. Additionally, quantification of left ventricular dyssynchrony acutely after myocardial infarction can predict LV remodeling [3]. Echocardiographic methods to assess regional myocardial motion suffer under several limitations such as a poor acoustic window or through-plane motion. Magnetic resonance (MR) CSPAMM tagging [4,5] combined with harmonic phase analysis (HARP, 6) allow for fast and accurate quantification of regional motion parameters. However, the acquisition of multi-slice MR tagging data covering the whole heart in shortand long axis orientations is associated with extensively long acquisition times and prone to slice misregistration. In this study, a novel accelerated 3D tagging acquisition scheme [7,8] was employed allowing the acquisition of volumetric 3D tagging data of the entire LV in only three breath-holds. Accordingly, the method is easily integrated into a clinical protocol including volumetric, perfusion and viability measurements. Similar spatial and temporal resolutions are obtained as in conventional 2D tagging acquisitions. The 3D tagging technique was applied to quantify LV dyssynchrony in patients after acute myocardial infarctions as a model causing dyssynchrony relative to healthy controls. Features of three-dimensional motion patterns were correlated with the presence of scar tissue as measured with late enhancement images.