Figure 1.

Schematic of electromechanical measurements. (A) Identification of local time of depolarization (TD) and its left-ventricular endocardial distribution in a bullseye view. Transeptal time (TST) is defined as the time interval between the onset of the QRS complex and the earliest TD measured in the left-ventricular endocardial cavity. Total left-ventricular time (TLVAT) is defined as the time interval between the earliest and latest TD. (B) Identification of the local time-to-peak shortening (TPS) as the earliest peak of the local area strain curve. (C) The time intervals between the earliest and latest TD or TPS define TVLAT and the total left-ventricular activation mechanical time (TLVMT). The regression line between TD and TPS describes the electromechanical coupling. (D) Schematic for the computation of the systolic stretch index (SSI). After normalizing the strain curves by subtracting the average strain curve, SSI is defined as the sum of the early systolic posterolateral stretch (SPS_Lat) and the late septal systolic rebound stretch (SRS_Sept). See text for details.