Echocardiographic assessment of mechanical dyssynchrony: are the new parameters better?

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Introduction - The high cost and important non-response rate are preventing optimal use of cardiac resynchronization therapy (CRT). Assessing mechanical dyssynchrony on echocardiography in candidates for CRT could remove these barriers by improving patient selection. In 2008 the PROSPECT study compared several old parameters of dyssynchrony in search of a reproducible parameter capable of better predicting response to CRT. Unfortunately, the results were disappointing and the assessment of dyssynchrony became discredited. Promising new parameters have been developed but a comparison with the old parameters is currently missing. Purpose - To compare the old and new parameters of mechanical dyssynchrony for (1) their effect on response to CRT as additional selection criteria, (2) predicting favourable long-term outcome after CRT and (3) their reproducibility. Methods - 146 CRT patients were analysed retrospectively in a multicentre setting. Mechanical dyssynchrony was assessed using three old parameters: 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: 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’. The ‘non-eligible’ were considered untreated. Results were compared to the guidelines (Fig. 1). The hazard ratio (HR) for cardiac death within 5 years after implantation was computed for all patients (Fig. 2), and intra- and interrater agreement was determined. Results - 73% (n= 107) of patients showed response to CRT. The old parameters maintained less than 75% of the original responders. SFoAR preserved the highest proportion of responders (93%), while reducing the number of non-responders by 39% (Fig. 1). The prediction of cardiac death was significant for SFoAR (HR = 0.29; 95% CI: 0.12-0.74; P = 0.009) and IVMD (HR = 0.32; 95% CI: 0.13-0.79; P = 0.014) (Fig. 2). Intra- and interrater agreement was best for SFoAR (κ = 0.89; 95% CI: 0.67-1.0 and κ = 0.78; 95% CI: 0.50-1.0 respectively). Interrater agreement was poor for all old parameters (κ < 0.6). Conclusion - The new parameters for dyssynchrony are performing better. The visual presence of apical rocking or septal flash provided the most responders to CRT, predicted favourable long-term outcome and was highly reproducible. Our results show that future research should focus on the new parameters. Abstract Figure. Abstract Figure.