Multimodality imaging derived energy loss index and outcome after transcatheter aortic valve replacement

Abstract

Aims To assess whether the combination of transthoracic echocardiography (TTE) and multidetector computed tomography (MDCT) data affects the grading of aortic stenosis (AS) severity under consideration of the energy loss index (ELI) in patients undergoing transcatheter aortic valve replacement (TAVR). Methods and results Multimodality imaging was performed in 197 patients with symptomatic severe AS undergoing TAVR at the University Hospital Zurich, Switzerland. Fusion aortic valve area index (fusion AVAi) assessed by integrating MDCT derived planimetric left ventricular outflow tract area into the continuity equation was significantly larger as compared to conventional AVAi (0.41 ± 0.1 vs. 0.51 ± 0.1 cm2/m2; P < 0.01). A total of 62 patients (31.4%) were reclassified from severe to moderate AS with fusion AVAi being >0.6 cm2/m2. ELI was obtained for conventional AVAi and fusion AVAi based on sinotubular junction area determined by TTE (ELILTL 0.47 ± 0.1 cm2/m2; fusion ELILTL 0.60 ± 0.1 cm2/m2) and MDCT (ELIMDCT 0.48 ± 0.1 cm2/m2; fusion ELIMDCT 0.61 ± 0.05 cm2/m2). When ELI was calculated with fusion AVAi the effective orifice area was >0.6 cm2/m2 in 85 patients (43.1%). Survival rate 3 years after TAVR was higher in patients reclassified to moderate AS according to multimodality imaging derived ELI (78.8% vs. 67%; P = 0.01). Conclusion Multimodality imaging derived ELI reclassifies AS severity in 43% undergoing TAVR and predicts mid-term outcome.

Energy-loss index does not improve risk prediction in aortic stenosis compared to conventional aortic valve area assessment

“…Reclassification was considered to occur if a patient received a lower grade of AS severity using ELI compared to AVAi, e.g. severe by AVAi but moderate by ELI (>0.6 cm 2 /m 2 but <0.85 cm 2 /m 2 ), as per previous studies on pressure recovery adjustment of AS grade 11,12,14 .…”

“…These findings contrast previous studies on the prognostic value of pressure recovery adjustment of AS severity. 10,[12][13][14] After showing in vitro that the energy loss could be accounted for using information on AVA and aortic area only, 138 patients with moderate or severe AS with a combined endpoint of death or AVR were evaluated over 8 months follow-up. 10 In that study, ELI was the only significant aortic valve measure associated with survival in multivariable analysis.…”

“…These patients had lower AV mean gradient, as well as lower Agatson scores. 14 Of note, the same principles of echocardiographically assessing AS severity before intervention apply regardless of whether the aortic valve intervention is surgical or using a transcatheter approach. Hence, there is no reason why pressure recovery adjustment would have different consequences for different interventional methods.…”

“…Reclassification was considered to occur if a patient received a lower grade of AS severity using ELI compared to AVAi, e.g. severe by AVAi but moderate by ELI (>0.6 cm 2 /m 2 but <0.85 cm 2 /m 2 ), as per previous studies on pressure recovery adjustment of AS grade 11, 12, 14 . Cox regression was used to determine whether reclassification from either severe to moderate AS, or from moderate to mild was associated with improved survival.…”

“…10 Moving from smaller experimental studies to larger epidemiological studies, attempts have been made to prove that pressure recovery is a clinically relevant parameter in the risk assessment of patients with AS. [11][12][13][14] However, evidence of improved risk assessment by using ELI instead of unadjusted AVA is scarce, and results have either been driven by aortic valve replacement numbers 10,13 or flawed by not considering pre-existing differences between patients that were reclassified after pressure recovery adjustment to those that were not 12,14 Despite previous attempts, it is still not known whether pressure recovery adjustment improves risk stratification of AS patients. Therefore, we aimed to evaluate the prognostic value of both AVAi and ELI in a head-to-head comparison using large-scale, real-world data.…”