Low Muscle Mass by Preprocedural Computed Tomography Is Associated With Worse Short-Term Outcomes in Transcatheter Aortic Valve Replacement Recipients.

Low muscle mass (LMM) is associated with worse outcomes in various clinical situations. Traditional frailty markers have been used for preoperative risk stratification in patients who underwent transcatheter aortic valve replacement (TAVR). However, preoperative imaging provides an opportunity to directly quantify skeletal muscle mass to identify patients at higher risk of procedural complications. We reviewed all TAVR recipients from January to December 2018 and included subjects with preprocedural chest computed tomography. Multi-slice automated measurements of skeletal muscle mass were made from the ninth to twelfth thoracic vertebrae and normalized by height squared to obtain skeletal muscle index (cm2/m2). LMM was defined as the lowest gender-stratified skeletal muscle index tertile. Strength testing was collected during pre-TAVR evaluation. Primary outcome was a composite of perioperative complications, 1-year rehospitalization, or 1-year mortality. In our cohort, 238 patients met inclusion criteria, and 80 (33.6%) were identified to have LMM. Patients with LMM were older with lower body mass index, decreased grip strength, lower hemoglobin A1c, and higher N-terminal pro-brain natriuretic peptide. They had greater rates of the composite outcome and 2-year all-cause mortality, which remained significant on multivariable adjustment (hazard ratio 1.71, 95% confidence interval 1.05 to 2.78, p = 0.030 and hazard ratio 2.31, 95% confidence interval 1.02 to 5.24, p = 0.045, respectively) compared with patients without LMM; there was no significant difference in 5-year all-cause mortality. In conclusion, LMM was associated with an increase in the primary composite outcome and 2-year all-cause mortality in TAVR recipients. Using automatic muscle processing software on pre-TAVR computed tomography scans may serve as an additional preoperative risk stratification tool.

Tantalum oxide nanoparticles as versatile contrast agents for X-ray computed tomography.

Here, we describe the synthesis, characterization and in vitro and in vivo performance of a series of tantalum oxide (TaOx) based nanoparticles (NPs) for computed tomography (CT). Five distinct versions of 9-12 nm diameter silane coated TaOx nanocrystals (NCs) were fabricated by a sol-gel method with varying degrees of hydrophilicity and with or without fluorescence, with the highest reported Ta content to date (78%). Highly hydrophilic NCs were left bare and were evaluated in vivo in mice for micro-CT of full body vasculature, where following intravenous injection, TaOx NCs demonstrate high vascular CT contrast, circulation in blood for ∼3 h, and eventual accumulation in RES organs; and following injection locally in the mammary gland, where the full ductal tree structure can be clearly delineated. Partially hydrophilic NCs were encapsulated within mesoporous silica nanoparticles (MSNPs; TaOx@MSNPs) and hydrophobic NCs were encapsulated within poly(lactic-co-glycolic acid) (PLGA; TaOx@PLGA) NPs, serving as potential CT-imagable drug delivery vehicles. Bolus intramuscular injections of TaOx@PLGA NPs and TaOx@MSNPs to mimic the accumulation of NPs at a tumor site produce high signal enhancement in mice. In vitro studies on bare NCs and formulated NPs demonstrate high cytocompatibility and low dissolution of TaOx. This work solidifies that TaOx-based NPs are versatile contrast agents for CT.