Dose-dependent effects of red blood cell transfusion and case mix index on venous thromboembolic events in spine surgery.

BACKGROUND AND OBJECTIVES: Venous thromboembolic (VTE) events represent a major source of morbidity and mortality in spine surgery. Our goal was to assess whether a dose-response relationship exists between red blood cell (RBC) transfusion and postoperative VTE events among spine surgery patients. MATERIALS AND METHODS: A total of 786 spine surgery patients at a single institution who received at least 1 RBC unit perioperatively were included (2016-2019). Patients were stratified based on RBC transfusion volume: 1-2 units (39.3%), 3-4 units (29.4%), 5-6 units (15.9%) and ≥7 units (15.4%). Subgroup analyses were performed after stratification by case mix index, a standardized surrogate for patients' disease severity and comorbidities. Multivariable regression was used to assess risk factors for the development of postoperative VTE events. RESULTS: The overall VTE event rate was 2.4% (n = 19). A dose-response relationship was seen between RBC transfusion volume and VTE events (1-2 units: 0.97%, 3-4 units: 1.30%, 5-6 units: 3.20%, ≥7 units: 7.44%; p < 0.01). Similar dose-response relationships were seen between case mix index and VTE events (1.00-3.99: 0.52%, 4.00-6.99: 2.68%, ≥7.00: 9.00%; p < 0.01). On multivariable regression, larger RBC transfusion volumes (adjusted odds ratio [OR] 1.18 per RBC unit, 95% confidence interval [CI] 1.07-1.29; p < 0.01) and higher case mix index scores (adjusted OR 1.39 per unit increase, 95% CI 1.14-1.69; p < 0.01) were associated with an increased risk of thrombosis. CONCLUSION: Larger RBC transfusion volumes and higher case mix index scores were associated with an increased risk of VTE events. Physicians should be aware of how these dose-response relationships can influence a patient's risk of developing thrombotic complications postoperatively.

Modifiable Clinical Correlates of Vascular Health in Children and Adolescents with Dyslipidemia.

Atherosclerosis promoting cardiovascular disease risk factors (CVDrf) are highly prevalent among youth in the U.S. Determining which standard modifiable clinical measures (SMCMs) has the greatest impact on vascular structure and function is valuable for the health care provider to help identify children at highest risk. The aim of this study was to determine modifiable outpatient clinical predictors of vascular health in youth with CVDrf. Children and adolescents with CVDrf (n = 120, 13.1 ± 1.9 years, 49% female) were recruited from a pediatric preventive cardiology clinic. The SMCMs included BMI z-score, waist-to-height ratio (WTHR), lipid panel, hemoglobin A1c, blood pressure (BP), presence of tobacco smoke exposure, and presence of hypertriglyceridemic waist (HTW) phenotype (triglycerides ≥ 110 mg/dL and waist circumference ≥ 90 percentile). Vascular function and structure were measured with pulse wave velocity (PWV), central systolic BP (CSP), augmentation index (AIx), and carotid artery intima-media thickness (cIMT). Sex and height specific z-scores for PWV, CSP, and cIMT were used. Multiple linear regression with backwards selection identified SMCMs which strongly predicted vascular function and structure. Among SMCMs, WTHR and HTW were the most frequent predictors of vascular function (PWV: R2 = 0.32; CSP: R2 = 0.35; AIx R2 = 0.13). Other predictors of vascular function included hemoglobin A1C, BP, and BMI z-score. Systolic BP and LDL cholesterol were predictors of vascular structure (cIMT: R2 = 0.14). The strongest predictors of vascular health in youth with CVDrf were related to measures of central obesity. Targeting these SMCM in lieu of vascular testing in outpatient clinic setting may be practical to identify children and adolescents at greatest risk for CVD.

Outcomes of Mechanical Mitral Valve Replacement in Children.

BACKGROUND: Mitral valve anomalies in children are rare but frequently severe, recalcitrant, and not often amenable to primary repair, necessitating mechanical mitral valve replacement (M-MVR). This study examined outcomes of a cohort undergoing a first M-MVR at age younger than 21 years. METHODS: We queried the Pediatric Cardiac Care Consortium, a multi-institutional United States-based cardiac intervention registry, for patients undergoing first M-MVR for 2-ventricle congenital heart disease. Survival and transplant status through 2014 were obtained from Pediatric Cardiac Care Consortium and linkage with the National Death Index and the Organ Procurement and Transplantation Network. RESULTS: We identified 441 patients (median age, 4.3 years; interquartile range, 1.3 to 10.1 years) meeting study criteria. The commonest disease necessitating M-MVR was atrioventricular canal (44.3%). Early mortality (death <90 days after M-MVR) was 11.1%; there was increased risk of early death if age at M-MVR was younger than 2 years (odds ratio, 7.8; 95% confidence interval [CI], 1.1 to 56.6) and with concurrent other mechanical valve placement (odds ratio, 8.5; 95% CI, 2.0 to 35.6). In those surviving more than 90 days after M-MVR, transplant-free survival was 76% at 20 years of follow-up (median follow-up, 16.6 years; interquartile range, 11.9 to 21.3 years). Adjusted analysis in those who survived more than 90 days showed elevated risk of death/transplant for boys (hazard ratio, 1.5; 95% CI, 1.0 to 2.3), age at M-MVR younger than 2 years (10-year survival: hazard ratio, 4.3; 95% CI, 1.2 to 15.1), and nonbileaflet prosthesis placement (hazard ratio, 2.4; 95% CI, 1.3 to 4.3). CONCLUSIONS: M-MVR is a viable strategy in children with unrepairable mitral valve disease. Age younger than 2 years at the first M-MVR is associated with significant early risk of death and poorer long-term survival.

Lipoprotein (a): Examination of Cardiovascular Risk in a Pediatric Referral Population.

Atherosclerotic cardiovascular disease (CVD), a leading cause of death globally, has origins in childhood. Major risk factors include family history of premature CVD, dyslipidemia, diabetes mellitus, and hypertension. Lipoprotein (a) [Lp(a)], an inherited lipoprotein, is associated with premature CVD, but its impact on cardiovascular health during childhood is less understood. The objective of the study was to examine the relationship between Lp(a), family history of premature CVD, dyslipidemia, and vascular function and structure in a high-risk pediatric population. This is a single-center, cross-sectional study of 257 children referred to a preventive cardiology clinic. The independent variable, Lp(a), separated children into high-Lp(a) [Lp(a) ≥ 30 mg/dL] and normal-Lp(a) groups [Lp(a) < 30 mg/dL]. Dependent variables included family history of premature CVD; dyslipidemia, defined as low-density lipoprotein cholesterol > 130 mg/dL, high-density lipoprotein cholesterol (HDL-C) < 45 mg/dL, triglycerides (TG) > 100 mg/dL; and vascular changes suggesting early atherosclerosis, as measured by carotid-femoral pulse wave velocity (PWV) and carotid artery intima-media thickness (CIMT). Of the 257 children, 110 (42.8%) had high Lp(a) and 147 (57.2%) had normal Lp(a). There was a higher prevalence of African-American children in the high-Lp(a) group (19.3%) compared to the normal-Lp(a) group (2.1%) (p < 0.001). High Lp(a) was associated with positive family history of premature CVD (p = 0.03), higher-than-optimal HDL-C (p = 0.02), and lower TG (p < 0.001). There was no difference in PWV or CIMT between groups. High Lp(a) in children is associated with family history of premature CVD and is prevalent in African-American children. In children with high Lp(a), promotion of intensive lifestyle modifications is prudent to decrease premature CVD-related morbidity.