Figure 1.

Left ventricular systolic function and work asymmetry. (A) Effect of cardiac resynchronization therapy on left ventricular volumes and function: Volumes and ejection fraction were similar in responders and non-responders before cardiac resynchronization therapy, but improved significantly only in responders. (B) Effects of cardiac resynchronization therapy on work: Before cardiac resynchronization therapy, responders have more work in the left ventricular lateral wall and less in the septum than non-responders (upper panels). This is reflected in a larger lateral-to-septal work difference (mid-panels). With cardiac resynchronization therapy, lateral wall work is reduced and septal work increased in both groups. Among responders, however, reduction in lateral wall work was far exceeded by increased septal work and explains why only responders showed improved global work (lower panels). One standard deviation indicated.