Computer-based assessment of ventricular mechanical synchrony from magnetic resonance imaging.

Abstract

Cardiac resynchronization therapy (CRT) has revolutionized the care of a substantial portion of patients with advanced heart failure (HF). From current guideline (NYHA III or IV heart failure, left ventricular ejection fraction ≤35% and ECG QRS duration ≥ 120 ms), CRT improves clinical status in about 70% of those treated. Ideally, the ability to accurately predict likelihood of response will enhance the quality of treatment. This study aims to develop an automated method to assess left ventricular mechanical synchrony from magnetic resonance imaging (MRI), which has been considered as gold standard cardiac imaging for ventricular structure and function assessment. 26 healthy volunteers (age ranges from 24 years to 73 years) were prospectively recruited and underwent standard MRI scans. MRI images (e.g. 2-chamber, 3-chamber and 4-chamber views) were processed and atrioventricular junction (AVJ) motions were auto-tracked during cardiac cycle. The myocardial velocities Sm1 and Sm2 at systolic phase; Em and Am at early and late mitral filing phase, were derived respectively. The time to these measures (e.g., TSm1, TSm2, TEm and TAm) were determined and ventricular synchrony indices TSm1-SD-6, TSm2-SD-6, TEm-SD-6 and TAm-SD-6 (standard deviations of TSm1, TSm2, TEm and TAm for 6 AVJ points) were assessed and correlated with age. The computational time per dataset is approximately 5 minutes. One-way ANOVA analysis found that there were no significant differences in time to peak velocities in 6 segments. Second, linear regression analysis found that there were no significant correlation between TSm2-SD-6 and TAm-SD-6 with age, and fair positive correlation between TSm1-SD-6 and TEm-SD-6 with age. In this prospective study, noninvasive ventricular synchrony derived from typically acquired MRI images offers a novel method that may enable ventricular mechanical dyssynchrony assessment in heart failure.