Cardiac magnetic resonance assessment of mechanical dyssynchrony

PURPOSE OF REVIEW: Echocardiographic techniques have played a major role in the assessment of mechanical dyssynchrony and the selection of patients for cardiac resynchronization therapy. The accuracy and reliability of such measures, however, have recently been placed under great scrutiny. This has shifted interest to cardiovascular magnetic resonance as an alternative method to assess myocardial dyssynchrony but these methods are relatively underdeveloped and not used widely clinically. Accordingly, the purpose of this review is to highlight existing and emerging CMR acquisition methods for quantifying dyssynchrony as well as the potential role of CMR to improve patient selection for CRT. RECENT FINDINGS: CMR has a number of advantages over current echocardiographic methods for the assessment of myocardial dyssynchrony including quantitative assessment of circumferential strain and myocardial scar burden and distribution. Recent studies also demonstrate the ability to perform CMR in patients with CRT devices. SUMMARY: CMR assessment of myocardial dyssynchrony is a logical alternative to echocardiographic based methods that provides highly quantitative and reproducible data sets of function and scar that are predictive of CRT response. The future ability to perform CMR imaging in patients pre-CRT and post-CRT may for the first time allow full characterization of CRT response.