Introduction:
In 2008 the PROSPECT-study compared several parameters of mechanical dyssynchrony (MD) for predicting response to cardiac resynchronization therapy (CRT).
The parameters performed poorly and echocardiography for selecting patients for CRT became discredited. Promising new parameters have emerged, but a comparison of the old and new parameters is missing.

Purpose:
To compare the old and new parameters of MD for (1) identifying volume responders 1 year after CRT, (2) predicting cardiac death within 5 years after CRT, and (3) reproducibility in a population of heart failure patients referred for CRT.

Methods:
146 patients referred for CRT in accordance with guidelines were analysed retrospectively in a multicentre setting. MD was assessed using three old parameters of dyssynchrony: septal-to-posterior-wall-motion-delay (SPWMD), left-ventricular-filling-time/cardiac-cycle-ratio (LVFT/RR), and intraventricular-mechanical-delay (IVMD); and three new parameters of dyssynchrony: systolic stretch index (SSI), myocardial work index (MWI), and visual presence of septal flash or apical rocking (SFoAR). Response to CRT was defined as a ≥15% decrease in LV end-systolic volume 1 year after CRT. For each parameter patients were categorized using previously published cut-offs as ‘eligible’ or ‘non-eligible’ for CRT. For a given parameter the ‘non-eligible’ were considered not implanted. The ‘eligible’ were categorized as responders or non-responders in accordance with their respective changes in LVESV. The guideline population served as reference. The hazard ratio (HR) for cardiac death within 5 years after implantation was computed for all patients, and intra-rater and inter-rater agreement was determined.

Results
73% (n= 107) of patients were responders. All old parameters identified <75% of the responders. SFoAR preserved the highest proportion of responders (93%) and reduced non-response rate by 39%. Cardiac death was predicted by SFoAR (HR = 0.29; P = 0.009) and IVMD (HR = 0.32; P = 0.014). Intra-rater and inter-rater agreement was best for SFoAR (κ=0.89 and κ=0.78 respectively). Inter-rater agreement was poor for all old parameters (κ<0.6).

Conclusion:
The new parameters for dyssynchrony outperform the old.
The visual presence of apical rocking or septal flash provided the most CRT responders, predicted favourable long-term outcome and was highly reproducible.
Our results suggests the new parameters of mechanical dyssynchrony should be tested in prospective randomized trials and could be used for selection CRT candidates.

 



Figure 1
Performance of the dyssynchrony parameters as selection criterion for CRT. The guideline population served as reference.
Figure 2
Hazard ratios for cardiac death within 5 years after CRT implantation including the 95%-CIs and P-values. P-value < 0.05 is significant.
Death due to heart failure, sudden cardiac death or death of an undetermined cause are considered as cardiac death.
Figure 3