Measuring integrated backscatter in patients undergoing transcatheter aortic valve implantation

Abstract Funding Acknowledgements Type of funding sources: None. Background Calibrated integrated backscatter (cIB) derived by 2D echocardiography quantifies myocardial ultrasound reflectivity, and it has been used in previous studies as a surrogate for myocardial fibrosis. Before the advent of other cardiac imaging techniques, it was a major focus of tissue characterization research. Purpose We examined whether cIB may help identify patients undergoing transcatheter aortic valve implantation (TAVI) at risk of procedure-related complications. Methods Consecutive patients submitted to transfemoral TAVI between January 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. Measurements of cIB, expressed in decibels, were performed at end-diastole. The primary endpoint was the occurrence of major TAVI-related complications. Results Of 149 patients that underwent TAVI during the study period, 131 had a reasonable acoustic window for cIB measurement and were included in the study. Patient mean age was 82.1±6.9 years, and 62% were female. At baseline, 84% of patients had preserved left ventricle function, the mean aortic mean gradient was 47.3±14.8 mmHg, and the mean Euroscore II was 5.34±3.24. The global mean cIB measured was 19.74±7.56 dB. No significant differences were found in the myocardial wall ultrasound reflectivity in patients with TAVI-related major complications (20.63±10.8 vs 19.6±6.9 dB, p = 0.587), which were defined according to the Valve Academic Research Consortium-2 consensus. However, cIB was significantly higher in patients who had post-TAVI conduction disturbances (21.09±7.72 vs 18.11±7.06 dB, p = 0.026), including left bundle branch block and atrioventricular block. There was also a negative correlation of cIB with aortic annulus area as measured by computed tomography (r(129)= −0.19, p = 0.032), and cIB was also significantly higher in patients who had 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 Our data disfavors the use of cIB as a predictor of major TAVI-related complications, but it suggests that cIB assessment could add value in identifying patients at risk of conduction disturbances in post-TAVI procedures.