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Left atrial (LA) myopathy plays a critical role in the pathophysiology of heart failure with preserved ejection fraction (HFpEF). This study aimed to evaluate LA function in a murine model of hypertension-induced HFpEF, with and without obesity, by analyzing left ventricular (LV) pressure signals to quantify the contribution of LA systole to total LV volume. HFpEF was induced in C57BL/6J mice using the SAUNA model, which involves uninephrectomy, chronic aldosterone infusion, and high-salt drinking water for four weeks. To model obesity-associated HFpEF, a high-fat diet (HFD) was added to the SAUNA protocol. Invasive hemodynamic measurements were obtained, and a novel method was developed to assess atrial systole using the second-order derivative of the LV pressure signal during diastolic filling. SAUNA HFpEF mice exhibited preserved LVEF, moderate hypertension, pulmonary congestion, and diastolic dysfunction as evidenced by a prolonged time constant of relaxation (Tau). In sham control mice, atrial systole accounted for 23.0 ± 2.4% of LV volume, whereas this contribution was significantly reduced to 13.9 ± 2.3% in SAUNA HFpEF mice ( P < 0.01). In obese sham controls, atrial systole contributed 53.1 ± 2.2%, which was markedly decreased to 36.8 ± 3.6% in obese-SAUNA HFpEF mice ( P < 0.003). This novel method enables precise quantification of LA systolic contribution to LV filling in mice and highlights the pathophysiological effects of hypertension and obesity on LA function in HFpEF.

Background and Goals: Spontaneous bacterial peritonitis (SBP) is a serious complication in patients with cirrhosis and ascites, with additional risks posed by multidrug-resistant organisms (MDRO). This real-world study evaluated clinical outcomes in patients with SBP and the impact of MDRO. Methods: This study identified US adults with SBP receiving guideline-recommended treatment with antibiotics and albumin from January 2012 to June 2022. Antibiotic utilization trends, health care resource utilization, and clinical outcomes [in-hospital and ICU mortality and hospital and ICU length of stay (LOS)] were assessed and stratified by MDRO status. Results: A total of 10,956 patients with 12,570 encounters were identified. Median age was 57.0 years (IQR=49.0 to 65.0), and 62.4% were male; suspected MDRO infections occurred in 15% of encounters. Third-generation cephalosporins were used in 71.6%, 49.2% had acute kidney injury, and 20.0% and 7.2% had hepatorenal syndrome and hepatic encephalopathy, respectively. Median hospital LOS was 7.2 days (IQR=4.3 to 12.9), with 17.7% in-hospital mortality. ICU care was required in 14.5% of encounters, with a median ICU LOS of 3.6 days (IQR=1.7 to 6.7) and ICU mortality of 29.7%. MDRO infections were associated with increased in-hospital mortality (OR=2.24, P <0.001) and decreased hazard of hospital discharge (ie, prolonged LOS; HR=0.43, P <0.001). Receiving albumin within 24 hours of admission was associated with a 72% higher hazard of hospital discharge (ie, shorter LOS; HR=1.72, P <0.001). Conclusion: This study highlights the clinical and resource burden of SBP, emphasizing the impact of MDRO infections and the importance of timely albumin administration concordant with clinical guidelines.

ABSTRACT Purpose To explore the opioid decision‐making process of prescribers in primary care, surgery, and subspecialty pain management. Methods This was a multistage qualitative‐qualitative study with clinicians involved in opioid prescribing and management from a single healthcare organization with locations in Minnesota, Florida, Arizona, and Wisconsin. Clinicians in this study included physicians, nurse practitioners (NPs), and physician assistants (PAs) practicing in primary care, surgery, or pain medicine. The interview guide was organized in three domains of a conceptual model for opioid use: (1) prescriber characteristics, (2) patient characteristics, and (3) practice environment characteristics. Individual interviews ( N = 20) were performed first, and data were summarized using a rapid template‐based approach. Subsequently, focus groups (FGs) ( N = 4) were conducted with an additional 21 clinicians to confirm and explore interview results. Data from interviews and FGs were analyzed using a common codebook. Results Findings were organized as decision factors into the three domains. Factors in the prescriber domain included characteristics such as formal pain management training, as well as factors that influenced knowledge and beliefs (e.g., advice from or observation of supervising clinicians and expert colleagues). Decision factors in the patient domain included patient pain etiology, comorbid medical or mental health conditions, and demographic characteristics. Clinicians' perceptions of these factors, such as viewing older age as having lesser risk for opioid misuse, influenced prescribing decisions. Clinicians also described challenges associated with “legacy patients” whose therapy was previously managed by a different clinician. Primary care clinicians, in particular, expressed difficulties managing post‐surgical or trauma‐related pain after care transition. Relevant decision factors reported by prescribers in the practice environment domain included guidelines and practice oversight. Most participants reported practicing in an environment that promoted conservative opioid use and having access to standardized institutional guidelines that reduced perceived decision‐making burden. Clinicians described how they used prescribing guidelines to help them communicate with patients about opioid use and prescribing decisions. Conclusions Intersecting prescriber, patient, and practice environment factors shape opioid analgesic prescribing decisions. Available resources in the practice environment, including peer input and institutional guidelines, may support clinician decision‐making and conversations with patients at the point of care, including in cases where patients have complex histories or personal characteristics that influence decision making.

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ABSTRACT Introduction Although covalent Bruton's tyrosine kinase inhibitors (cBTKis) have transformed treatment of chronic lymphocytic leukemia and small lymphocytic leukemia (CLL/SLL), cBTKi‐related cardiotoxicity is a known side effect. This real‐world study evaluated incident cardiovascular adverse events (CVAE), healthcare resource utilization (HCRU), and costs among patients with CLL/SLL receiving cBTKis. Methods Adult patients with CLL/SLL who initiated ibrutinib or acalabrutinib treatment (index date) between 2020 and 2023 were identified using US claims data and followed up to 36 months post‐index. Incident CVAEs (not present pre‐index) were assessed during cBTKi treatment and patients were stratified by CVAE status. HCRU and costs were evaluated per 1000 patient‐months (PPPM). Results Overall, 2069 patients were identified (mean age of 73.7 ± 9.1 years, 40.4% female) with a mean treatment‐specific observation period of 11.4 ± 9.5 months. At least one incident CVAE was observed in 442 (21.4%) patients. The incidence rate was 21.6 PPPM for hypertension, 8.9 PPPM for atrial fibrillation, 8.6 PPPM for ventricular arrhythmias, and 8.3 PPPM for atrial flutter. Patients with incident CVAEs had significantly more total medical service days PPPM (4334 vs. 3138, p < 0.001), primarily driven by increased inpatient (690 vs. 230), outpatient (2798 vs. 2425), other visit (662 vs. 375), and ER days (184 vs. 109) than those without CVAEs. Total healthcare costs (PPPM) were substantially higher for patients with incident CVAEs ($20,250,560 vs. $17,413,460, p < 0.001) mainly due to higher inpatient ($3,417,948 vs. $915,839, p < 0.001), outpatient ($2,415,060 vs. $1,769,628, p < 0.01), and ER costs ($186,820 vs. $87,585, p < 0.001). Conclusions The observed class‐effect of high CVAEs with cBTKis underscores the unmet need for safer, more selective agents for CLL/SLL treatment. The HCRU and economic burden remain high for CLL/SLL, especially among patients experiencing CVAEs during cBTKi treatment. These findings emphasize the importance of optimizing clinical management to reduce CVAE risk and downstream impacts on HCRU and costs.

Abstract The sections in this article are: Basic Concepts—Review of Muscle Mechanics Muscle Fiber Types Mechanics of Muscle Electrical Properties of Skeletal Muscle Individual Respiratory Muscles and Their Properties General Considerations Diaphragm Intercostal Muscles Sternocleidomastoid and Scalenus Muscles Abdominal Muscles Other Respiratory Muscles Altered Respiratory Muscle Mechanical Properties in Disease Obstructive Lung Disease Diseases Characterized by Stiff Lungs Neuromuscular Diseases Severe Obesity

Abstract The sections in this article are: Mechanism of Expiratory Flow Limitation Wave‐Speed Limitation Viscous Flow Limitation Computational Model Measurement and Analysis Volume‐Time Flow‐Volume Relative Merits of Presentations Volume‐Time Flow‐Volume Additional Considerations Volume and Time History Effects of Changing Gas Properties Dysanaptic Growth Axial Bronchial Tension Thoracoabdominal Mechanics

Abstract The sections in this article are: Lung Volumes Volume‐Pressure Relations of Respiratory System During Relaxation Total Respiratory System Chest Wall and Lung Effects of Gravity and Posture Changes Throughout Life Span Volume‐Pressure Relations of Respiratory System During Static Muscular Efforts Alveolar Pressure Abdominal and Thoracic Pressures Factors Limiting Volume Extremes Upper Volume Extreme Lower Volume Extreme