Key result
Cardiac resynchronization therapy significantly shortened isovolumetric contraction time derived from seismocardiography (from 63.2 to 52.6 ms, p=0.027) and increased systolic amplitudes.
Why the study?
Some patients with conduction-induced heart failure and LBBB do not respond to CRT, partly due to poor optimization of the AV pacing delay, prompting investigation into pacing-induced changes in the seismocardiogram.
Does CRT pacing improve seismocardiogram-derived cardiac timing intervals and amplitudes in patients with heart failure and LBBB?
Observational (n=28)
Does CRT pacing improve seismocardiogram-derived cardiac timing intervals and amplitudes in patients with heart failure and LBBB?
Seismocardiography can detect cardio-mechanic changes in response to CRT, such as shortened IVCT and increased amplitudes, though abnormal waveforms in patients may complicate interpretation.
Seismocardiography may detect acute CRT effects in heart failure; hypothesis-generating for non-invasive monitoring, needs larger validation.
Objective. Conduction-induced heart failure in patients with left bundle branch block (LBBB) can benefit from cardiac resynchronization therapy (CRT). However, some patients are non-responders to the therapy with one contributing factor being poor optimization of the atrioventricular (AV) pacing delay. In this study, we have investigated the pacing-induced changes in the seismocardiogram (SCG). Approach. 14 patients with heart failure, LBBB, and CRT were included. SCG was recorded with pacing turned on and off. Based on a mean SCG heartbeat from each patient, fiducial points were annotated, and cardiac timing intervals (CTI) and amplitudes were derived. These were compared between the CRT group and a group of healthy normal subjects ( n = 14). Echocardiography was also used to derive CTI. Intervals derived from the SCG and echocardiogram were correlated. Main results. The isovolumetric contraction time (IVCT) derived from SCG was significantly shorter in the CRT group when the pacemaker was turned on (63.2–52.6 ms, p = 0.027). The first peak-to-peak amplitude in the systolic complex was significantly larger with the pacemaker turned on ( p = 0.002), as well as the ∣max-min∣ amplitude in the systolic complex ( p = 0.003). Isovolumetric relaxation time and left ventricular ejection time (LVET) were not significantly different between pacemaker settings. Compared to normal subjects, IVCT was significantly prolonged with the pacemaker turned off. All amplitudes were significantly larger in the healthy subject group. IVCT and LVET derived from SCG were significantly correlated to the echocardiogram. Significance. IVCT shortened and SCG amplitudes increased in response to CRT, indicating a more efficient ventricular contraction. This demonstrates the possibility to detect cardio-mechanic changes in response to treatment with the SCG. However, for the patients the systolic part of the SCG was abnormal and difficult to characterize, raising concerns about the correct interpretation of the SCG.
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Sørensen et al. (2022) conducted an observational in Heart failure with left bundle branch block (n=28). Cardiac resynchronization therapy (pacing turned on) vs. Pacing turned off was evaluated on Isovolumetric contraction time (IVCT) derived from seismocardiogram (p=0.027). Cardiac resynchronization therapy significantly shortened isovolumetric contraction time derived from seismocardiography (from 63.2 to 52.6 ms, p=0.027) and increased systolic amplitudes.
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