The Differential Impact of Medicaid Expansion on Disparities in Outcomes Following Peripheral Vascular Intervention.

BACKGROUND: Peripheral artery disease (PAD) disproportionately affects nonwhite, Hispanic/Latino, and low socioeconomic status patients, who are less likely to have insurance and routine healthcare visits. Medicaid expansion (ME) has improved insurance rates and access to care, potentially benefitting these patients. We sought to assess the impact of ME on disparities in outcomes after peripheral vascular intervention (PVI) for PAD. METHODS: A retrospective analysis of prospectively-collected Vascular Quality Initiative PVI procedures between 2011 and 2019 was conducted. The sample was restricted to first-record procedures in adults under the age 65 in states that expanded Medicaid on January 1, 2014 (ME group) or had not expanded before January 1, 2019 (non-expansion [NE] group). ME and NE groups were compared between pre-expansion (2011-2013) and post-expansion (2014- 2019) time periods to assess baseline demographic and operative differences. We used difference-in-differences multivariable logistic regression adjusted for patient factors and clinical center and year fixed effects. Our primary outcome was 1-year major amputation. Secondary outcomes included trends in presentation, 30-day mortality, 1-year mortality, and 1-year primary and secondary patency. Outcomes were stratified by race and ethnicity. RESULTS: We examined 34,313 PVI procedures, including 20,378 with follow-up data. Rates of Medicaid insurance increased post-expansion in ME and NE states (ME 16.7% to 23.0%, P < 0.001; NE 10.0% to 11.9%, P = 0.013) while rates of self-pay decreased in ME states only (ME 4.6% to 1.8%, P < 0.001; NE 8.1% to 8.4%, P = 0.620). Adjusted difference-in-differences analysis revealed lower odds of urgent/emergent PVI among all patients and all nonwhite patients in ME states post-expansion compared to NE states (all: odds ratio [OR] 0.53 [95% confidence interval 0.33-0.87], P = 0.011; nonwhite: OR 0.41 [0.19-0.88], P = 0.023). No differences were observed for 1-year major amputation (OR 0.70 [0.43-1.14], P = 0.152), primary patency (OR 0.93 [0.63-1.38], P = 0.726), or secondary patency (OR 1.29 [0.69-2.41], P = 0.431). Odds of 1-year mortality were higher in ME states post-expansion compared to NE states (OR 2.50 [1.07-5.87], P = 0.035), although 30-day mortality was not different (OR 2.04 [0.60-6.90], P = 0.253). Notably, odds of 1-year major amputation among Hispanic/Latino patients decreased in ME states post-expansion compared to NE states (OR 0.11 [0.01-0.86], P = 0.036). CONCLUSIONS: ME was associated with lower odds of 1-year major amputation among Hispanic/Latino patients who underwent PVI for PAD. ME was also associated with lower odds of urgent/emergent procedures among patients overall and nonwhite patients specifically. However, 1-year mortality increased in the overall cohort. Further study is needed to corroborate our findings that ME may have benefits for certain underserved populations with PAD.

Treating Peripheral Artery Disease in the Wake of Rising Costs and Protracted Length of Stay.

BACKGROUND: There has been growing scrutiny in the treatment of patients with peripheral artery disease due to the utilization of resources to manage this complex patient population. The purpose of this study was to determine the factors associated with prolonged length of stay (LOS > 7 days) following lower extremity bypass using data from the Vascular Quality Initiative as well as to define the additional costs incurred due to prolonged LOS in our health system. METHODS: Summary statistics were performed of patients undergoing lower extremity bypass from 2010 to 2015. Student's t-tests and χ2 tests were performed to compare those with and without prolonged LOS. Multivariable logistic regression was then performed to determine the independent predictors for increased LOS. We then compared our institutional LOS with that of representative institutions from the University Health System Consortium and evaluated the impact of prolonged LOS on limb salvage and survival. RESULTS: This study included 334 patients with a mean age of 66.4 ± 12.4 years, 64.7% males, 58.5% of white race, 11.1% on dialysis, 80.5% smokers, and 53.6% with diabetes. The mean LOS was 15.7 ± 12.2 days. Prolonged LOS was associated with transfer (15.4% vs. 2.3%, P = 0.001), diabetes (58.3% vs. 40.2%, P = 0.004), critical limb ischemia (71.3% vs. 49.4%, P < 0.001), preoperative need for ambulatory assistance (44.5% vs. 16.1%, P < 0.001), prior ipsilateral bypass (6.9% vs. 1.1%, P = 0.042), urgent surgery (39.7% vs. 9.8%, P < 0.001), tibial or distal target vessel (52.7% vs. 28.0%, P < 0.001), use of vein (65.4% vs. 46.3%, P = 0.002), return to operating room (42.6% vs. 1.2%, P < 0.001), ambulatory assistance (65.0% vs. 34.1%, P < 0.001) as well as discharge anticoagulant (22.8% vs. 9.8%, P = 0.010). Multivariable logistic regression identified urgency (odds ratio [OR] = 5.09, 95% confidence interval [CI] 2.16-12.02, P < 0.001), critical limb ischemia (OR = 3.12, 95% CI 1.65-5.90, P < 0.001), return to OR (OR = 40.30, 95% CI 5.36-303.20, P < 0.001), use of vein (OR = 2.19, 95% CI 1.18-4.07, P = 0.013), and the need for anticoagulation at discharge (OR = 2.56, 95% CI 1.03-6.33, P = 0.043) as independent predictors of LOS > 7 days. Prolonged hospital stays accounted for an additional $40,561.64 in total cost and $26,028 in direct costs incurred. Despite these increased costs, limb salvage and overall survival were not adversely impacted in the prolonged LOS group in follow-up. CONCLUSIONS: Lower extremity bypass is associated with a longer than expected LOS in our health system, much of which can be attributed to return to the OR for minor amputations and wound issues. This led to added total and direct costs, where the majority of this increase was attributable to prolonged LOS. Limb salvage and overall survival were preserved, however, in this subset of patients in follow-up. These findings suggest that lower extremity bypass patients are a resource-intensive population of patients, but that these costs are worthwhile in the setting of preserved limb salvage and overall survival.

Temporal Changes in Infarct Material Properties: An In Vivo Assessment Using Magnetic Resonance Imaging and Finite Element Simulations.

BACKGROUND: Infarct expansion initiates and sustains adverse left ventricular (LV) remodeling after myocardial infarction (MI) and is influenced by temporal changes in infarct material properties. Data from ex vivo biaxial extension testing support this hypothesis; however, infarct material properties have never been measured in vivo. The goal of the current study was to serially quantify the in vivo material properties and fiber orientation of infarcted myocardium over a 12-week period in a porcine model of MI. METHODS: A combination of magnetic resonance imaging (MRI), catheterization, finite element modeling, and numeric optimization was used to analyze posterolateral MI. Specifically, properties were determined by minimizing the difference between in vivo strains and volume calculated from MRI and strains and volume predicted by finite element modeling. RESULTS: In 1 week after MI, the infarct region was found to be approximately 20 times stiffer than normal diastolic myocardium. Over the course of 12 weeks, the infarct region became progressively less stiff as the LV dilated and ejection fraction decreased. The infarct thinned by nearly half during the remodeling period, and infarct fiber angles became more circumferentially oriented. CONCLUSIONS: The results reported here are consistent with previously described ex vivo biaxial extension studies of infarct material properties and the circumferential change of collagen orientation in posterolateral infarcts. The current study represents a significant advance in that the method used allows for the serial assessment of an individual infarct in vivo over time and avoids the inherent limitations related to the testing of excised tissues.

Predicting the need for muscle flap salvage after open groin vascular procedures: a clinical assessment tool.

Groin wound complications after open vascular surgery procedures are common, morbid, and costly. The purpose of this study was to generate a simple, validated, clinically usable risk assessment tool for predicting groin wound morbidity after infra-inguinal vascular surgery. A retrospective review of consecutive patients undergoing groin cutdowns for femoral access between 2005-2011 was performed. Patients necessitating salvage flaps were compared to those who did not, and a stepwise logistic regression was performed and validated using a bootstrap technique. Utilising this analysis, a simplified risk score was developed to predict the risk of developing a wound which would necessitate salvage. A total of 925 patients were included in the study. The salvage flap rate was 11.2% (n = 104). Predictors determined by logistic regression included prior groin surgery (OR = 4.0, p < 0.001), prosthetic graft (OR = 2.7, p < 0.001), coronary artery disease (OR = 1.8, p = 0.019), peripheral arterial disease (OR = 5.0, p < 0.001), and obesity (OR = 1.7, p = 0.039). Based upon the respective logistic coefficients, a simplified scoring system was developed to enable the preoperative risk stratification regarding the likelihood of a significant complication which would require a salvage muscle flap. The c-statistic for the regression demonstrated excellent discrimination at 0.89. This study presents a simple, internally validated risk assessment tool that accurately predicts wound morbidity requiring flap salvage in open groin vascular surgery patients. The preoperatively high-risk patient can be identified and selectively targeted as a candidate for a prophylactic muscle flap.

Statistical assessment of normal mitral annular geometry using automated three-dimensional echocardiographic analysis.

BACKGROUND: The basis of mitral annuloplasty ring design has progressed from qualitative surgical intuition to experimental and theoretical analysis of annular geometry with quantitative imaging techniques. In this work, we present an automated three-dimensional (3D) echocardiographic image analysis method that can be used to statistically assess variability in normal mitral annular geometry to support advancement in annuloplasty ring design. METHODS: Three-dimensional patient-specific models of the mitral annulus were automatically generated from 3D echocardiographic images acquired from subjects with normal mitral valve structure and function. Geometric annular measurements including annular circumference, annular height, septolateral diameter, intercommissural width, and the annular height to intercommissural width ratio were automatically calculated. A mean 3D annular contour was computed, and principal component analysis was used to evaluate variability in normal annular shape. RESULTS: The following mean ± standard deviations were obtained from 3D echocardiographic image analysis: annular circumference, 107.0 ± 14.6 mm; annular height, 7.6 ± 2.8 mm; septolateral diameter, 28.5 ± 3.7 mm; intercommissural width, 33.0 ± 5.3 mm; and annular height to intercommissural width ratio, 22.7% ± 6.9%. Principal component analysis indicated that shape variability was primarily related to overall annular size, with more subtle variation in the skewness and height of the anterior annular peak, independent of annular diameter. CONCLUSIONS: Patient-specific 3D echocardiographic-based modeling of the human mitral valve enables statistical analysis of physiologically normal mitral annular geometry. The tool can potentially lead to the development of a new generation of annuloplasty rings that restore the diseased mitral valve annulus back to a truly normal geometry.

Qualitative impact of the endovascular era on vascular surgeons' comfort level and enjoyment with open and endovascular AAA repairs.

OBJECTIVE: To evaluate the qualitative impact of training in the endovascular era (post-2000) on vascular surgeons' comfort level and enjoyment with abdominal aortic aneurysm (AAA) repairs. METHODS: A sample of vascular surgeons (n = 1754) were sent a survey pertaining to their fellowship training and practice of AAA repair. The influence of training- and practice-related variables on qualitative outcomes was assessed. RESULTS: A total of 382 (22%) surgeons completed the survey. Surgeons who performed more endovascular aneurysm repairs (EVARs) than open AAA repairs were more likely to enjoy EVAR (P < .001). Those completing fellowship after 2000 reported a higher level of procedure-related comfort with EVAR (P = .001) compared to those completing fellowship before 2000. Conversely, surgeons completing fellowship before 2000 reported a higher level of procedure-related comfort with open AAA repair (P = .001). CONCLUSION: The advent of EVAR has changed fellowship training of AAA repair and has translated into changes in both practice patterns and comfort level.

Mitral valve tenting index for assessment of subvalvular remodeling.

BACKGROUND: Ischemic mitral regurgitation results from a variable combination of annular dilatation and remodeling of the subvalvular apparatus. Current surgical techniques effectively treat annular dilatation, but methods for addressing subvalvular remodeling have not been standardized. An effective technique for determining the extent of subvalvular remodeling could improve surgical results by identifying patients who are unlikely to benefit from annuloplasty alone. METHODS: A well-characterized ovine model of ischemic mitral regurgitation was used. Real-time three-dimensional echocardiography was performed on each animal at baseline and at 1 hour and 8 weeks after infarction. Multiple valvular geometric measurements were calculated at each time point. RESULTS: Immediate and long-term changes in mitral valvular geometry were observed. Annular height-to-commissural width ratio decreased from 20.0% +/- 1.6% to 11.2% +/- 0.9% 1 hour after infarction (p < 0.001) and to 9.4% +/- 0.4% 8 weeks after infarction (p < 0.001), whereas mitral annular area increased from 8.1 +/- 0.3 cm2 to 9.2 +/- 0.4 cm2 (p < 0.05) and then to 10.5 +/- 0.6 cm2 (p < 0.05). Maximum mitral valve tenting area increased from 49.7 +/- 5.1 mm2 to 58.6 +/- 4.2 mm2 (p < 0.05) and then to 106.4 +/- 3.9 mm2 (p < 0.001), whereas mitral valve tenting volume increased from 679.0 +/- 75.5 mm3 to 828.6 +/- 102.4 mm3 (p = 0.050) and then to 1530.5 +/- 97.8 mm3 (p < 0.001). The mitral valve tenting index increased from 0.83 +/- 0.08 mm to 0.88 +/- 0.08 mm (p > 0.05) and then to 1.46 +/- 0.08 mm (p < 0.001). CONCLUSIONS: We have described a technique that uses real-time three-dimensional echocardiography to perform a comprehensive assessment of leaflet tethering on the entire mitral valve. Our methodology is not influenced by viewing plane selection, regional tenting asymmetry, or annular dilatation and therefore represents a potentially useful, clinically relevant, and consistent measure of subvalvular remodeling.

Border zone geometry increases wall stress after myocardial infarction: contrast echocardiographic assessment.

After myocardial infarction (MI), the border zone expands chronically, causing ventricular dilatation and congestive heart failure (CHF). In an ovine model (n = 4) of anteroapical MI that results in CHF, contrast echocardiography was used to image short-axis left ventricular (LV) cross sections and identify border zone myocardium before and after coronary artery ligation. In the border zone at end systole, the LV endocardial curvature (K) decreased from 0.86 +/- 0.33 cm(-1) at baseline to 0.35 +/- 0.19 cm(-1) at 1 h (P < 0.05), corresponding to a mean decrease of 55%. Also in the border zone, the wall thickness (h) decreased from 1.14 +/- 0.26 cm at baseline to 1.01 +/- 0.25 cm at 1 h (P < 0.05), corresponding to a mean decrease of 11%. By Laplace's law, wall stress is inversely proportional to the product K. h. Therefore, a 55% decrease in K results in a 122% increase in circumferential stress; a 11% decrease in h results in a 12% increase in circumferential stress. These findings indicate that after MI, geometric changes cause increased dynamic wall stress, which likely contributes to border zone expansion and remodeling.