Prognostic significance of calibrated integrated backscatter in patients submitted to transcatheter aortic valve implantation

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background There is a reported association between calibrated integrated backscatter (cIB) and myocardial fibrosis, mostly noted in cardiomyopathies and aortic stenosis cases. But whether this measure of myocardial ultrasound reflectivity could help predict outcomes in patients submitted to transcatheter aortic valve implantation has not been previously tested. Purpose To demonstrate whether cIB may help differentiate patients undergoing transcatheter aortic valve implantation (TAVI) at risk of major cardiovascular events. Methods Consecutive patients submitted to transfemoral TAVI between October 2020 and December 2021 were routinely imaged by echocardiography in the five days peri-procedure. Calibrated integrated backscatter was obtained from the parasternal long-axis view (PLAX) by subtracting pericardial cIB intensity from myocardial septal and posterior wall average cIB. Patients with poor PLAX views were excluded from the study. All measurements of cIB were performed at end-diastole. The primary endpoint was the occurrence of major cardiovascular events at one year of follow-up. Results A total of 184 patients underwent a TAVI procedure during the study period. Of these, 159 had a reasonable acoustic window for cIB measurement and were included in the study. Patient mean age was 81.1±6.1 years, and 58% were female. At baseline, 81% of patients had preserved left ventricle function, the mean aortic mean gradient was 44.8±15.1 mmHg, and the mean Euroscore II was 5.55±3.75. No significant association was found between cIB and TAVI-related major acute complications (21.02±10.4 vs 19.8±7.1 dB, p = 0.544). There was also no significant correlation of cIB with major cardiovascular events (19.71±7.25 vs 20.39±10.47 dB, p = 0.478) or with valve safety (19.59±7.07 vs 18.84±10.32 dB, p = 0.709), defined accordingly to the Valve Academic Research Consortium-2 consensus, at one-year follow-up. There was, however, a positive association between cIB and all-cause mortality (19.24±7.06 vs 22.92±9.36, p = 0.021) at one-year follow-up, with deaths occurring due to multiple causes, mainly cardiovascular, infectious, and neoplastic. Measured cIB was also significantly higher in patients with a pre-TAVI estimated glomerular filtration rate of less than 30 mL/min/1.73m2 (22.42±7.17 vs 19.56±6.88 dB, p = 0.043). Conclusion Higher cIB was not associated with a higher risk of major cardiovascular events or with valve safety in patients submitted to TAVI, but it can potentially have prognostic value in differentiating patients at increased risk of all-cause mortality.