Effect of cardiac resynchronization therapy on regional left ventricular function: a speckle tracking strain analysis.

Aims: The mechanisms associated with cardiac resynchronization therapy (CRT) benefits have been elucidated in part, however little is known about the effects of biventricular pacing (BVP) on regional myocardial contractility.
Methods and Results: Twenty patients with conventional CRT criteria were studied before and after device implantation. Speckle tracking strain analysis was performed from standard bidimensional acquisitions during different pacing configurations. Longitudinal and transverse strains were measured for the six basal left ventricular (LV) segments. Acute CRT improved LV end-diastolic and end-systolic volumes without significantly modifying LV ejection fraction. Moreover, CRT produced significant changes in regional strain. When compared with spontaneous rhythm, simultaneous BVP caused a significant increase in longitudinal septal strain (-4.8 vs. -7.3%, P = 0.003) and a significant decrease in longitudinal lateral strain (-8.2 vs. -5.9%, P = 0.03). Simultaneous BVP also induced a significant decrease in transverse lateral strain from 17.9 to 10.9% (P = 0.004).
Conclusion: In this acute echocardiographic study, BVP decreased lateral wall deformation while improving septal wall contraction, thus potentially improving LV contractile pattern.