Table 2 Measurement of the components of the optimal AV delay according to Ismer et al. [22]

pacemaker-related interatrial conduction interval (IACT)

VDD pacing: MA-LA measured between right-atrial sense-event marker (MA) and the beginning of left-atrial deflection (LA) in oesophageal electrogram

DDD pacing: SA-LA measured between right-atrial pacing stimulus (S_A) and the beginning of left-atrial deflection (LA) in oesophageal electrogram

left-atrial electromechanical action (LA-EAC_long)

Measured during unphysiologically long programmed AV delay between the beginning of left-atrial deflection (LA) in oesophageal electrogram and the end of the left-atrial contribution (EAC) in transmitral flow.

left-ventricular electromechanical latency period (Sv-EAC_short)

Measured during unphysiologically short programmed AV delay between ventricular pacing stimulus (Sv) and the end of the left-atrial contribution (EAC) in transmitral flow.