Verwey transition as evolution from electronic nematicity to trimerons via electron-phonon coupling.

Understanding the driving mechanisms behind metal-insulator transitions (MITs) is a critical step toward controlling material's properties. Since the proposal of charge order-induced MIT in magnetite Fe3O4 in 1939 by Verwey, the nature of the charge order and its role in the transition have remained elusive. Recently, a trimeron order was found in the low-temperature structure of Fe3O4; however, the expected transition entropy change in forming trimeron is greater than the observed value, which arises a reexamination of the ground state in the high-temperature phase. Here, we use electron diffraction to unveil that a nematic charge order on particular Fe sites emerges in the high-temperature structure of bulk Fe3O4 and that, upon cooling, a competitive intertwining of charge and lattice orders arouses the Verwey transition. Our findings discover an unconventional type of electronic nematicity in correlated materials and offer innovative insights into the transition mechanism in Fe3O4 via the electron-phonon coupling.

Utilization of guideline-directed medical therapy in patients with de novo heart failure with reduced ejection fraction: A Veterans Affairs study.

BACKGROUND: The utilization of guideline-directed medical therapy (GDMT) significantly reduces morbidity and mortality in patients with heart failure with reduced ejection fraction (HFrEF). Previous studies have documented the underutilization of GDMT in HFrEF. The present study aimed to determine reasons for underutilization and achievement of target doses of GDMT in patients with de novo diagnosis of HFrEF. METHODS: Patients presenting with de novo HFrEF at the Veterans Affairs Medical Center were included. Baseline demographic, clinical, and echocardiographic data were collected. The utilization of target doses of GDMT was assessed at the time of discharge and 1-, 3-, 6-, and 12-month follow-up. RESULTS: Of the 95 patients who met the criteria for de novo HFrEF, 48 were included in the final analysis. Dose titration of either beta-blocker or angiotensin converting enzyme inhibitors/angiotensin receptor blockers (ACEi/ARB) was attempted in 20 patients (42%) at 1 month, 21 patients (44%) at 3 months, 13 patients (27%) at 6 months, and 14 patients (29%) at 12 months. Nine (19%) patients were on a target dose of beta-blockers and three (6%) patients were on a target dose of an ACEi/ARB at 12 months. The most common reasons for underutilization were patient-level factors, such as hypotension, acute kidney injury/hyperkalemia, and patient noncompliance. CONCLUSIONS: Utilization and achievement of target doses of GDMT were suboptimal among patients discharged with de novo HFrEF during a 1-year follow-up. Although patient factors may limit the up-titration of therapies, concerted efforts are needed to support primary care physicians in improving adherence to target doses of GDMT in patients with HFrEF.

Atrial myxoma and bone changes: a paraneoplastic syndrome?

Atrial myxomas are the most common benign tumors of the heart and are difficult to diagnose due to a wide variety of presenting symptoms. We present a patient with a five-year history of visual loss, vertigo, ataxia, tinnitus, and bone lesions that resolved after diagnosis and resection of an atrial myxoma. This case not only highlights an unusual presentation of atrial myxomas but also raises the question of whether atrial myxomas can produce paraneoplastic syndromes, including bone abnormalities.

A case of critical aortic stenosis masquerading as acute coronary syndrome.

Serum cardiac troponins I and T are reliable and highly specific markers of myocardial injury. Studies have shown that at least 20% of patients with severe aortic stenosis have detectable serum troponins. This case report describes a patient who presented as suspected acute coronary syndrome with markedly elevated troponin levels, who was later found to have normal coronaries and critical aortic stenosis. This case highlights the need for comprehensive and accurate physical examination in patients who present with angina. Critical aortic stenosis may cause such severe subendocardial ischemia as to cause marked elevation in cardiac markers and mimic an acute coronary syndrome. Careful physical examination will lead to an earlier use of non invasive techniques, such as echocardiography to confirm the correct diagnosis and the avoidance of inappropriate treatments such as intravenous nitroglycerin and glycoprotein IIb/IIIa inhibitors.