Publications by authors named "Natalie D Sridharan"

5 Publications

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New randomized controlled trials for abdominal aortic aneurysm treatment should focus on younger, good-risk patients.

J Vasc Surg 2021 Jun;73(6):2209

Division of Vascular Surgery, Department of Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pa.

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http://dx.doi.org/10.1016/j.jvs.2020.11.053DOI Listing
June 2021

Predictive Factors of Perioperative Stroke-Related Mortality Following Vascular Surgery: A Retrospective Analysis.

J Stroke Cerebrovasc Dis 2021 Jul 5;30(7):105833. Epub 2021 May 5.

Departments of Neurology and Neurosurgery, University of Pittsburgh Medical Center, Pittsburgh, PA, United States. Electronic address:

Objective: Vascular surgical procedures have one of the highest risks of perioperative stroke and stroke-related mortality, yet the independent risk factors contributing to this increased mortality have not been described. Perioperative strokes are thought to result from a combination of embolism and hypoperfusion mechanisms. The purpose of this study is to describe the independent predictors of perioperative stroke-related mortality in the vascular surgical population using the Pennsylvania Health Care Cost Containment Council (PHC4) database which collects cause of death data.

Methods: This retrospective, case-control study evaluated 4,128 patients aged 18-99 who underwent a vascular, non-carotid surgical procedure and subsequently suffered perioperative mortality. Common surgical comorbidities and risk factors for perioperative stroke, including carotid stenosis and atrial fibrillation, were evaluated in multivariate regression analysis.

Results: Patients with carotid stenosis were 2.6 (aOR, 95% CI 1.4-4.5) times more likely to suffer perioperative mortality from stroke than from other causes. Additionally, in-hospital stroke, history of stroke, admission from a healthcare facility, and cancer were all positive predictive factors, whereas atrial fibrillation, emergency admission, hypertension, and diabetes were associated with decreased risk of perioperative stroke-related mortality.

Conclusions: Identification of vascular surgical population-specific predictors of stroke-related mortality can help to enhance preoperative risk-stratification tools and guide perioperative management of identified high-risk patients. Increased neurophysiologic monitoring in the perioperative period to prevent delays in diagnosis of perioperative stroke offers a strategy to reduce risk of perioperative stroke-related mortality in vascular surgical patients.
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http://dx.doi.org/10.1016/j.jstrokecerebrovasdis.2021.105833DOI Listing
July 2021

Rationale and Design for the Remote Ischemic Preconditioning for Carotid Endarterectomy Trial.

Ann Vasc Surg 2019 Oct 12;60:246-253. Epub 2019 Jun 12.

UPMC, Division of Vascular Surgery, Pittsburgh, PA.

Background: While the perioperative stroke rate after carotid endarterectomy (CEA) is low, "silent" microinfarctions identified by magnetic resonance imaging (MRI) are common and have been correlated with postoperative neurocognitive decline. Our study will investigate the role of remote ischemic preconditioning (RIPC) as a potential neuroprotective mechanism. RIPC is a well-tolerated stimulus that, through neuronal and humoral pathways, generates a systemic environment of greater resistance to subsequent ischemic insults. We hypothesized that patients undergoing RIPC before CEA will have improved postoperative neurocognitive scores compared with those of patients undergoing standard care.

Methods: Patients undergoing CEA will be randomized 1:1 to RIPC or standard clinical care. Those randomized to RIPC will undergo a standard protocol of 4 cycles of RIPC. Each RIPC cycle will involve 5 min of forearm ischemia with 5 min of reperfusion. Forearm ischemia will be induced by a blood pressure cuff inflated to 200 mm Hg or at least 15 mm Hg higher than the systolic pressure if it is >185 mm Hg. This will occur after anesthesia induction and during incision/dissection but before manipulation or clamping of the carotid; thus, patients will be blinded to their assignment. Before carotid endarterectomy, all patients will undergo baseline neurocognitive testing in the form of a Montreal Cognitive Assessment (MoCA) and National Institutes of Health (NIH) Toolbox. MoCA testing only will be conducted on postoperative day 1 in the hospital. The full neurocognitive testing battery will again be conducted at 1-month follow-up in the office. Changes from baseline will be compared between arms at the follow-up time points. Assuming no drop-ins or dropouts and a 10% loss to follow-up, we would need a sample size of 43 patients for 80% power per treatment arm. The primary endpoint, change in MoCA scores, will be analyzed using a random effects model, and secondary outcomes will be analyzed using either linear or logistic regression where appropriate.

Conclusions: RIPC, if shown to be effective in protecting patients from neurocognitive decline after CEA, represents a safe, inexpensive, and easily implementable method of neuroprotection.
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http://dx.doi.org/10.1016/j.avsg.2019.03.014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6764906PMC
October 2019

Cost-effectiveness analysis of drug-coated therapies in the superficial femoral artery.

J Vasc Surg 2018 01 27;67(1):343-352. Epub 2017 Sep 27.

Division of Vascular Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pa.

Objective: Drug-coated balloons (DCBs) may increase durability of endovascular treatment of superficial femoral artery (SFA) disease while avoiding stent-related risks. The purpose of this study was to use meta-analytic data of DCB studies to compare the cost-effectiveness of potential SFA treatments: DCB, drug-eluting stent (DES), plain old balloon angioplasty (POBA), or bare-metal stent (BMS).

Methods: A search for randomized controlled trials comparing DCB with POBA for treatment of SFA disease was performed. Hazard ratios were extracted to account for the time-to-event primary outcome of target lesion revascularization. Odds ratios were calculated for the secondary outcomes of primary patency (PP) and major amputation. Incorporating pooled data from the meta-analysis, cost-effectiveness analysis, assuming a payer perspective, used a decision model to simulate patency at 1 year and 2 years for each index treatment modality: POBA, BMS, DCB, or DES. Costs were based on current Medicare outpatient reimbursement rates.

Results: Eight studies (1352 patients) met inclusion criteria for meta-analysis. DCB outperformed POBA with respect to target lesion revascularization over time (pooled hazard ratio, 0.41; P < .001). Risk of major amputation at 12 months was not significantly different between groups. There was significantly improved 1-year PP in the DCB group compared with POBA (pooled odds ratio, 3.30; P < .001). In the decision model, the highest PP at 1 year was seen in the DES index therapy strategy (79%), followed by DCB (74%), BMS (71%), and POBA (64%). With a baseline cost of $9259.39 per patent limb at 1 year in the POBA-first group, the incremental cost per patent limb for each other strategy compared with POBA was calculated: $14,136.10/additional patent limb for DCB, $38,549.80/limb for DES, and $59,748,85/limb for BMS. The primary BMS option is dominated by being more expensive and less effective than DCB. Compared directly with DCB, DES costs $87,377.20 per additional patent limb at 1 year. Based on the projected PP at 1 year in the decision model, the number needed to treat for DES compared with DCB is 20. At current reimbursement, the use of more than two DCBs per procedure would no longer be cost-effective compared with DES. At 2 years, DCB emerges as the most cost-effective index strategy with the lowest overall cost and highest patency rates over that time horizon.

Conclusions: Current data and reimbursements support the use of DCB as a cost-effective strategy for endovascular intervention in the SFA; any additional effectiveness of DES comes at a high price. Use of more than one DCB per intervention significantly decreases cost-effectiveness.
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http://dx.doi.org/10.1016/j.jvs.2017.06.112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5741471PMC
January 2018

An Accumulated Deficits Model Predicts Perioperative and Long-term Adverse Events after Carotid Endarterectomy.

Ann Vasc Surg 2018 Jan 6;46:97-103. Epub 2017 Jul 6.

Division of Vascular Surgery, Department of Surgery, UPMC, Pittsburgh, PA.

Background: There is increasing recognition that decreased reserve in multiple organ systems, known as accumulated deficits (AD), may better stratify perioperative risk than traditional risk indices. We hypothesized that an AD model would predict both perioperative adverse events and long-term survival after carotid endarterectomy (CEA), particularly important in asymptomatic patients.

Methods: Consecutive patients undergoing CEA between 1st January 2000 and 31st December 2010 were retrospectively identified. Seven of the deficit items from the Canadian Study of Health and Aging-frailty index (coronary disease, renal insufficiency, pulmonary disease, peripheral vascular disease, heart failure, hypertension, and diabetes) were tabulated for each patient. Predictors of perioperative and long-term outcomes were evaluated using regression analysis.

Results: About 1,782 CEAs in 1,496 patients (mean age: 71.3 ± 9.3 years, 56.3% male, 35.4% symptomatic) were included. The risk of major adverse events (stroke, death, or myocardial infarction) at 30 days for patients with ≤3 deficits was 2.53% vs. 8.81% for patients with ≥4 deficits (P < 0.001). For patients with ≥5 deficits, the risk was 15.18%. Each additional deficit increased the odds of a 30-day major adverse event and hospital stay >2 days by 1.64 (P < 0.001) and 1.15 (P < 0.001), respectively. In multivariate analysis, the presence of ≥4 deficits was more predictive of perioperative major adverse events (odds ratio [OR] = 3.62, P < 0.001) than symptomatology within 6 months (OR = 1.57, P = 0.08) or octogenarian status (OR = 2.00, P = 0.02). Kaplan-Meier analysis showed significantly decreased survival over time with accumulating deficits (P < 0.001). Patients with ≥4 deficits have a hazards ratio for death of 2.6 compared to patients with ≤3 deficits (P < 0.001). Overall survival is estimated at 79.5% (95% confidence interval [CI]: 0.77-0.82) at 5 years in patients with ≤3 deficits versus 52.4% (95% CI: 0.46-0.58) in patients with ≥4 deficits, respectively. In subgroup analysis of asymptomatic patients, 5-year survival for octogenarian male patients with ≥4 deficits was only 26.8%. For asymptomatic males aged 70-79 years with ≥4 deficits, 5-year survival was 59.9%.

Conclusions: An AD model is more predictive of perioperative adverse events after CEA than age or symptomatic status. This model remains predictive of long-term survival. In asymptomatic male octogenarians with 4 or more AD, 5-year survival is severely limited.
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http://dx.doi.org/10.1016/j.avsg.2017.06.150DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5828018PMC
January 2018