Quantification of Aortic Valve Fibrotic and Calcific Tissue from CTA: Prospective Comparison with Histology.

Background Quantifying the fibrotic and calcific composition of the aortic valve at CT angiography (CTA) can be useful for assessing disease severity and outcomes of patients with aortic stenosis (AS); however, it has not yet been validated against quantitative histologic findings. Purpose To compare quantification of aortic valve fibrotic and calcific tissue composition at CTA versus histologic examination. Materials and Methods This prospective study included patients who underwent CTA before either surgical aortic valve replacement for AS or orthotopic heart transplant (controls) at two centers between January 2022 and April 2023. At CTA, fibrotic and calcific tissue composition were quantified using automated Gaussian mixture modeling applied to the density of aortic valve tissue components, calculated as [(volume/total tissue volume) × 100]. For histologic evaluation, explanted valve cusps were stained with Movat pentachrome as well as hematoxylin and eosin. For each cusp, three 5-µm slices were obtained. Fibrotic and calcific tissue composition were quantified using a validated artificial intelligence tool and averaged across the aortic valve. Correlations were assessed using the Spearman rank correlation coefficient. Intermodality and interobserver variability were measured using the intraclass correlation coefficient (ICC) and Bland-Altman plots. Results Twenty-nine participants (mean age, 63 years ± 10 [SD]; 23 male) were evaluated: 19 with severe AS, five with moderate AS, and five controls. Fibrocalcific tissue composition strongly correlated with histologic findings (r = 0.92; P < .001). The agreement between CTA and histologic findings for fibrocalcific tissue quantification was excellent (ICC, 0.94; P = .001), with underestimation of fibrotic composition at CTA (bias, -4.9%; 95% limits of agreement [LoA]: -18.5%, 8.7%). Finally, there was excellent interobserver repeatability for fibrotic (ICC, 0.99) and calcific (ICC, 0.99) aortic valve tissue volume measurements, with no evidence of a difference in measurements between readers (bias, -0.04 cm3 [95% LoA: -0.27 cm3, 0.19 cm3] and 0.02 cm3 [95% LoA: -0.14 cm3, 0.19 cm3], respectively). Conclusion In a direct comparison, standardized quantitative aortic valve tissue characterization at CTA showed excellent concordance with histologic findings and demonstrated interobserver reproducibility. Clinical trial registration no. NCT06136689 Published under a CC BY 4.0 license. Supplemental material is available for this article. See also the editorial by Almeida in this issue.

Direct left ventricular wire pacing during transcatheter aortic valve implantation.

BACKGROUND: Rapid ventricular pacing is used during balloon aortic valvuloplasty, balloon­expandable transcatheter aortic valve implantation (TAVI), and for postdilatation. Right ventricular (RV) lead pacing has been regarded as a gold standard. Direct left ventricular (LV) wire pacing has recently been considered safe and effective in TAVI interventions. AIMS: This study aimed to analyze procedural outcomes of direct LV pacing compared with RV stimulation in unselected patients undergoing TAVI. METHODS: Direct LV wire pacing was provided via available preshaped guidewires and used only when no predictors of atrioventricular block were present. The primary study objective was the assessment of the efficacy of direct LV wire pacing. The secondary objectives included the evaluation of procedure duration and safety in comparison with the conventional method. A combined endpoint (major adverse cardiovascular event) was defined as the occurrence of death, stroke, venous puncture-related complications, and cardiac tamponade. RESULTS: In 2017 and 2018, 143 patients underwent transfemoral TAVI. Of these, 114 (79.7%) had self­ ­expandable valves implanted. Direct LV wire pacing was the dominant method of pacing (82 patients [57.3%]), and its efficacy reached 97.6%. The median (interquartile range) procedure time was shorter in the direct LV wire pacing group (80 [70-90] min vs 85 [70-95] min; P = 0.02). Major adverse cardiovascular events were more frequent in the RV lead pacing group (11.5% vs 4.9%), but no statistical significance was achieved (P = 0.13). CONCLUSIONS: Direct LV wire pacing during TAVI is a simple, reproducible, and safe technique, which provides reliable, sustained stimulation with a low complication rate and potential reduction of procedural time.