Existing Nongated CT Coronary Calcium Predicts Operative Risk in Patients Undergoing Noncardiac Surgeries (ENCORES).

BACKGROUND: Preoperative cardiovascular risk stratification before noncardiac surgery is a common clinical challenge. Coronary artery calcium scores from ECG-gated chest computed tomography (CT) imaging are associated with perioperative events. At the time of preoperative evaluation, many patients will not have had ECG-gated CT imaging, but will have had nongated chest CT studies performed for a variety of noncardiac indications. We evaluated relationships between coronary calcium severity estimated from previous nongated chest CT imaging and perioperative major clinical events (MCE) after noncardiac surgery. METHODS: We retrospectively identified consecutive adults age ≥45 years who underwent in-hospital, major noncardiac surgery from 2016 to 2020 at a large academic health system composed of 4 acute care centers. All patients had nongated (contrast or noncontrast) chest CT imaging performed within 1 year before surgery. Coronary calcium in each vessel was retrospectively graded from absent to severe using a 0 to 3 scale (absent, mild, moderate, severe) by physicians blinded to clinical data. The estimated coronary calcium burden (ECCB) was computed as the sum of scores for each coronary artery (0 to 9 scale). A Revised Cardiac Risk Index was calculated for each patient. Perioperative MCE was defined as all-cause death or myocardial infarction within 30 days of surgery. RESULTS: A total of 2554 patients (median age, 68 years; 49.7% women; median Revised Cardiac Risk Index, 1) were included. The median time interval from nongated chest CT imaging to noncardiac surgery was 15 days (interquartile range, 3-106 days). The median ECCB was 1 (interquartile range, 0-3). Perioperative MCE occurred in 136 (5.2%) patients. Higher ECCB values were associated with stepwise increases in perioperative MCE (0: 2.9%, 1-2: 3.7%, 3-5: 8.0%; 6-9: 12.6%, P<0.001). Addition of ECCB to a model with the Revised Cardiac Risk Index improved the C-statistic for MCE (from 0.675 to 0.712, P=0.018), with a net reclassification improvement of 0.428 (95% CI, 0.254-0.601, P<0.0001). An ECCB ≥3 was associated with 2-fold higher adjusted odds of MCE versus an ECCB <3 (adjusted odds ratio, 2.11 [95% CI, 1.42-3.12]). CONCLUSIONS: Prevalence and severity of coronary calcium obtained from existing nongated chest CT imaging improve preoperative clinical risk stratification before noncardiac surgery.

Molecular Thorium Compounds with Dichalcogenide Ligands: Synthesis, Structure, 77Se NMR Study, and Thermolysis.

A series of dimeric thorium disulfides and diselenides have been prepared with sterically undemanding ancillary ligands. Five complexes, (py)6Th2I4(µ2-S2)2, (py)6Th2Br2(SC6F5)2(µ2-S2)2, (py)6Th2I4(µ2-Se2)2, (py)6Th2I2(SC6F5)2(µ2-Se2)2, and (py)6Th2Br2(SC6F5)2(µ2-Se2)2, were isolated in high yields by first reducing mixtures of I2, F5C6SSC6F5, PhSeSePh, or PhSSPh, and PhSeBr with elemental Th, followed by in situ ligand-based redox reactions with elemental sulfur or selenium. These are the first examples of thorium compounds with bridging dichalcogenide ligands. Attempts to prepare chloride derivatives gave mixtures of (py)4ThCl4 and either (py)6Th2Cl2(SC6F5)2(µ2-S2)2 or (py)8Th4Se4(SePh)4(SC6F5)4. All products were characterized by single-crystal and powder X-ray diffraction and IR, UV-visible, and NMR spectroscopy. A computational analysis of experimental 77Se NMR chemical shifts reveals that the solvated dimeric structures with two bridging dichalcogenides are maintained in solution. Thermolysis of (py)6Th2I4(µ2-Se2)2 leads to reduction of the bridging Se22- moieties, oxidation of the I- ligand, and formation of solid-state ThSe2 and I2.

Thorium Cubanes-Synthesis, Solid-State and Solution Structures, Thermolysis, and Chalcogen Exchange Reactions.

Thorium cubanes (py)8Th4(µ3-E')4(µ2-EPh)4(η-EPh)4 (E, E' = S, Se) were prepared from ligand-based redox reactions of elemental E' with Th(EPh)4. Products with all four possible E/E' combinations (E,E' = S,S; Se,Se; S,Se; Se,S) were isolated and structurally characterized, ligand exchange reactions were explored, and the heterochalcogen compounds (py)8Th4(µ3-S)4(µ2-SePh)4(η-SePh)4 and (py)8Th4(µ3-Se)4(µ2-SPh)4(η-SPh)4 were heated to deliver solid solutions of ThS xSe2- x. NMR spectroscopy indicated that the structure of (py)8Th4(µ3-Se)4(µ2-SePh)4(η-SePh)4 is static in pyridine solution, with no exchange between bridging and terminal PhE- ligands on the NMR time scale. A computational analysis of 77Se NMR shifts provides insight into the solution structure of both clusters and monomeric chalcogenolates.

Thorium Compounds with Bonds to Sulfur or Selenium: Synthesis, Structure, and Thermolysis.

Thorium chalcogenolates Th(ER)4 (E = S, Se; R = Ph, C6F5) form pyridine complexes with a variety of coordination numbers. Four compounds, (py)4Th(SPh)4, (py)3Th(SePh)4, (py)3Th(SC6F5)4, and (py)4Th(SeC6F5)4, have been isolated and characterized by spectroscopic methods and low-temperature single crystal X-ray diffraction. Two of the products, (py)4Th(SPh)4 and (py)4Th(SeC6F5)4, have classic eight coordinate A4B4 square-antiprism geometries. The SePh compound is the only seven coordinate (4Se, 3N) product, and the fluorinated thiolate is distinctive in that the structure contains two dative interactions between Th and fluoride, to give a nine coordinate (3N, 4S, 2F) structure. The EPh compounds decompose thermally to give ThE2 and EPh2, while the fluorinated compounds give primarily ThF4, E2(C6F5)2, and E(C6F5)2.

Copper, indium, tin, and lead complexes with fluorinated selenolate ligands: precursors to MSex.

Reductive cleavage of C6F5SeSeC6F5 with elemental M (M = Cu, In, Sn, Pb) in pyridine results in the formation of (py)4Cu2(SeC6F5)2, (py)2In(SeC6F5)3, (py)2Sn(SeC6F5)2, and (py)2Pb(SeC6F5)2. Each group adopts a unique structure: the Cu(I) compound crystallizes as a dimer with a pair of bridging selenolates, two pyridine ligands coordinating to each Cu(I) ion, and a short Cu(I)-Cu(I) distance (2.595 Å). The indium compound crystallizes as monometallic five-coordinate (py)2In(SeC6F5)3 in a geometry that approximates a trigonal bipyramidal structure with two axial pyridine ligands and three selenolates. The tin and lead derivatives (py)2M(SeC6F5)2 are also monomeric, but they adopt nearly octahedral geometries with trans pyridine ligands, a pair of cis-selenolates, and two "empty" cis-positions on the octahedron that are oriented toward extremely remote selenolates (M-Se = 3.79 Å (Sn), 3.70 Å (Pb)) from adjacent molecules. Two of the four compounds (Cu, In) exhibit intermolecular π-π stacking arrangements in the solid state, whereas the stacking of molecules for the other two compounds (Sn, Pb) appears to be based upon molecular shape and crystal packing forces. All compounds are volatile and decompose at elevated temperatures to give MSex and Se(C6F5)2.The electronic structures of the dimeric Cu compound and monomeric (py)2M(SeC6F5)2 (M = Sn, Pb) were examined with density functional theory calculations.