Role of MRI in Patient Selection for CRT

Abstract

Magnetic resonance imaging has great potential for aiding in the selection of patients who will respond to CRT. MRI is the only imaging tool that can simultaneously assess mechanical dyssynchrony, determine the amount and location of myocardial scar tissue, and map the location of cardiac venous anatomy-three important factors in predicting a patient's response to CRT. The goal of this manuscript is to review the MRI methods that can be used in the selection of patients for CRT.

A practical approach to imaging dyssynchrony for cardiac resynchronization therapy

“…However, recent improvements in software have decreased the time for analysis and increased the potential clinical feasibility of this approach. Another CMR approach is phase contrast TVM, which provides velocity information based on the principles of encoding motion of myocardial spin along a magnetic field gradient [30,52,53]. It is similar to TDI in echocardiography, as it does not measure strain, but different in that it is not limited by acoustic windows.…”

“…Moreover, image acquisition appears to be less dependent on the operator or the patient. There are three major techniques that have been described for dyssynchrony measurement: myocardial tagging, tissue velocity mapping (TVM) [30,52,53], and displacement encoding with stimulated echoes (DENSE) [54][55][56]. Myocardial tagging uses saturation pulses either in parallel or in perpendicular to the image slice to produce a gridlike pattern (tissue tag) on the image of the myocardium.…”

Assessment of the coronary venous system in heart failure patients by blood pool agent enhanced whole-heart MRI

“…Several studies [7][8][9] suggest that patient selection can be significantly improved by adding functional dyssynchrony of the LV as a criterion. The motion data of the LV for example could be obtained by pre-operative ultrasound (US) [7][8][9][10], computed tomography (CT) [7][8][9]11], magnetic resonance imaging (MRI) [7,9,[12][13][14] or nuclear imaging [15]. Further improvement is expected from consideration of possible LV scar tissue [16] findings as well as its location and likely from pre-operative assessment of the accessibility of the targeted LV pacing location through the venous system for ensuring adequate transvenous pacing of the lateral wall of the LV.…”

“…Quantification of the LV function [9,[12][13][14][17][18][19][20][21][22] as well as assessment of the LV scar [16] can be derived from MRI data, enabling the identification of preferred implantation target sites. The assessment of the course of the coronary veins, however, has not yet been shown in the difficult-to-image heart failure patients but was restricted to mostly volunteer studies or coronary artery disease (CAD) patients scheduled for coronary artery MRI angiography [23][24][25][26][27].…”

Nonechocardiographic Imaging in Evaluation for Cardiac Resynchronization Therapy

“…CMR is a well-studied imaging technique with high reproducibility and high spatial resolution, which provides three-dimensional data on LV function and dyssynchrony, allows visualization of the coronary venous anatomy, and provides viability information 38,39 (Table 1, Figure 1). These features make it useful in CRT planning.…”