Assessment of bovine cortical bone fracture behavior using impact microindentation as a surrogate of fracture toughness

The fracture behavior of bone is critically important for evaluating its mechanical competence and ability to resist fractures. Fracture toughness is an intrinsic material property that quantifies a material's ability to withstand crack propagation under controlled conditions. However, properly conducting fracture toughness testing requires the access to calibrated mechanical load frames and the destructive testing of bone samples, and therefore fracture toughness tests are clinically impractical. Impact microindentation mimicks certain aspects of fracture toughness measurements, but its relationship with fracture toughness remains unknown. In this study, we aimed to compare measurements of notched fracture toughness and impact microindentation in fresh and boiled bovine bone. Skeletally mature bovine bone specimens (n = 48) were prepared, and half of them were boiled to denature the organic matrix, while the other half remained preserved in frozen conditions. All samples underwent a notched fracture toughness test to determine their resistance to crack initiation (KIC) and an impact microindentation test using the OsteoProbe to obtain the Bone Material Strength index (BMSi). Boiling the bone samples increased the denatured collagen content, while mineral density and porosity remained unaffected. The boiled bones also showed significant reduction in both KIC (P < .0001) and the average BMSi (P < .0001), leading to impaired resistance of bone to crack propagation. Remarkably, the average BMSi exhibited a high correlation with KIC (r = 0.86; P < .001). A ranked order difference analysis confirmed the excellent agreement between the 2 measures. This study provides the first evidence that impact microindentation could serve as a surrogate measure for bone fracture behavior. The potential of impact microindentation to assess bone fracture resistance with minimal sample disruption could offer valuable insights into bone health without the need for cumbersome testing equipment and sample destruction.

Targeting Endoplasmic Reticulum for Novel Therapeutics and Monitoring in Acute Kidney Injury

BACKGROUND

Endoplasmic reticulum (ER) stress response is a conservative mechanism involving a complex network of different molecular branches to determine cell fate through specific transcription factors and downstream executors. Emerging evidence shows that ER stress is implicated in the occurrence and progression of acute kidney injury (AKI) in different animal models and human patients. However, there is still a lack of therapeutics targeting the ER in AKI.

SUMMARY

Several therapeutic chemicals, including a compound that induces activating transcription factor 6 (ATF6) and chemical chaperones, have been developed to target the ER in the treatment of AKI. Meanwhile, ER stress-inducible secreted proteins, mesencephalic astrocyte-derived neurotrophic factor (MANF), and cysteine-rich with EGF-like domains 2 (CRELD2) could serve as potential ER stress biomarkers in the early diagnosis and treatment response monitoring of human patients with AKI.

KEY MESSAGES

Experimental and clinical evidence suggests the critical role of ER in the pathogenesis and progression of AKI, and ER is a novel target in AKI therapy.

A Comparison Between NOACs and Warfarin on Time to Elective Cardioversion

Cardioversion of atrial fibrillation is a procedure that has been commonly performed for over half a century. There is known to be an elevated risk of thromboembolism around the time of cardioversion, which has been shown to be drastically reduced with oral anticoagulation. The consistency of therapeutic anticoagulation in the weeks leading up to elective cardioversion is an important factor in the safety of the procedure. Until recently, the only option for oral anti-coagulation was Warfarin. The challenges of dosing Warfarin to achieve a therapeutic INR are well documented. In recent years, novel oral anticoagulant medications have been developed, which are thought to provide a consistent intensity of anticoagulation and do not require routine monitoring or dose adjustment. The purpose of this review is to examine the literature pertaining to a comparison of Warfarin versus novel oral anti-coagulants with respect to time of elective cardioversion.

Abstract 128: Catheter-based Ablation May Improve Survival in Patients with Acute Decompensated Heart Failure with Reduced Ejection Fraction and Atrial Fibrillation or Flutter with Rapid Ventricular Response

Background: There is no current evidence regarding safety and efficacy of various rhythm control strategies such as Amiodarone, electrical cardioversion (DCCV), catheter based ablation and other anti-arrhythmic drugs (AAD) for acute control of rapid ventricular response (RVR) in hospitalized patients with atrial fibrillation or flutter (AF/AFL) and acute decompensated heart failure with reduced ejection fraction (ADHFrEF).

Methods: Single center retrospective study from our registry of hospitalized patients with ADHFrEF and rapid AF/AFL over a 5-year period

Results: We included 52 patients with ADHFrEF and rapid AF/AFL (mean age, 64.3±13.9 years; 39 (75%) males; mean left ventricular EF [%], 29.4±8.1; median follow up duration [months], 13 [interquartile range, 5.3-19]): 30 (57.7%) received amiodarone, 19 (36.5%) received DCCV, 10 (19.2%) received catheter ablation and 1 (1.9%) received other AAD. Patients who were treated with catheter ablation had significantly higher rates of survival to median follow up and to hospital discharge compared to those who were not treated with ablation. There were no significant differences in symptoms control, major bleeding event, systemic embolism, worsening HF, procedure related complications, and length of hospital stay between patients treated with and without amiodarone, DCCV and catheter ablation (Table 1). New onset AF/AFL, new HF, left ventricular EF, NYHA functional class, and loading with AAD did not predict response to DCCV (P = 0.22-0.87) (Table 2).

Conclusion: Acute control of rapid AF/AFL in hospitalized patients with ADHFrEF using catheter ablation significantly improved survival. Catheter-based ablation may be a safe and efficacious treatment option for these patients.

Education of Physicians and Implementation of a Formal Referral System Can Improve Cardiac Rehabilitation Referral and Participation Rates after Percutaneous Coronary Intervention

BACKGROUND

Cardiac rehabilitation (CR) is an effective preventive measure that remains underutilised in the United States. The study aimed to determine the CR referral rate (RR) after percutaneous coronary intervention (PCI) at an academic tertiary care centre, identify barriers to referral, and evaluate awareness of CR benefits and indications (CRBI) among cardiologists. Subsequently, it aimed to evaluate if an intervention consisting of physicians' education about CRBI and implementation of a formal CR referral system could improve RR and consequently participation rate (PR).

METHODS

Data were retrospectively collected for all consecutive patients who underwent PCI over 12 months. Referral rate was determined and variables were compared for differences between referred and non-referred patients. A questionnaire was distributed among the physicians in the Division of Cardiology to assess awareness of CRBI and referral practice patterns. After implementation of the intervention, data were collected retrospectively for consecutive patients who underwent PCI in the following six months. Referral rate and changes in PRs were determined.

RESULTS

Prior to the intervention, RR was 17.6%. Different barriers were identified, but the questionnaire revealed lack of physicians' awareness of CRBI and inconsistent referral patterns. After the intervention, RR increased to 88.96% (Odds Ratio 37.73, 95% CI 21.34-66.70, p<0.0001) and PR increased by 32.8% to reach 26%. Personal endorsement of CRBI by cardiologists known to patients increased CR program graduation rate by 35%.

CONCLUSIONS

Cardiologists' awareness of CRBI increases CR RR and their personal endorsement improves PR and compliance. Education of providers and implementation of a formal referral system can improve RR and PR.

My Patient Taking A Novel Oral Anticoagulant Needs Surgery, Device Implantation, Or Ablation

Atrial fibrillation (AF) is a highly prevalent chronic condition and a growing number of patients are on chronic anticoagulation therapy with novel oral anticoagulant (NOAC) agents: dabigatran, rivaroxaban, and apixaban. Many of these patients are expected to require invasive procedures. There is no clear consensus regarding the peri-procedural management of patients using NOACs, as to how to minimize both bleeding risk and thromboembolism risk. This review of the current available literature is designed to help formulate peri-procedural anticoagulation strategies for patients with AF taking NOACs who are being considered for catheter ablation, device implant, or other surgery. To help frame the discussion, we offer 3 case vignettes that we will revisit to at the end of the review of the existing literature. Case 1: A 62 year-old female with hypertension, diabetes, and symptomatic paroxysmal AF who is prescribed dabigatran for thromboembolism prevention. She has failed attempts at maintaining sinus rhythm with antiarrhythmic drugs. She is now being considered for catheter ablation of AF. Case 2: A 76 year-old male with hypertension, diabetes, prior stroke, and ischemic cardiomyopathy who has persistent drug-refractory AF. He is maintained on chronic anticoagulation with dabigatran for thromboembolism prevention. He has an implantable cardioverter-defibrillator (ICD) which requires a generator change. Case 3: A 58 year-old male with hypertension and paroxysmal AF who takes rivaroxaban for thromboembolic prophylaxis and is being considered for a knee replacement surgery.

Prognostic value of normal stress echocardiography in obese patients

BACKGROUND

Chest pain is a common problem in obese patients. Because of the body habitus, the results of noninvasive evaluation for CAD may be limited in this group.

METHODS

We reviewed the records of 1446 consecutive patients who had undergone clinically indicated stress echocardiography (SE). We compared major adverse cardiac events (MACE; myocardial infarction, cardiac intervention, cardiac death, subsequent hospitalization for cardiac events, and emergency department visits) at 1 year in normal weight, overweight, and obese subjects with normal SE.

RESULTS

Excluding patients with an abnormal and indeterminate SE and those who were lost to follow-up, a retrospective analysis of 704 patients was performed. There were 366 obese patients (BMI ≥ 30), 196 overweight patients (BMI 25-29.9), and 142 patients with normal BMI (18.5-24.9). There was no MACE in the groups at 1-year follow-up after a normal SE.

CONCLUSIONS

In obese patients including those with multiple risk factors and symptoms concerning for cardiac ischemia, stress echocardiography is an effective and reliable noninvasive tool for identifying those with a low 1-year risk of cardiac events.