Salvianolic acid B inhibits thrombosis and directly blocks the thrombin catalytic site.

Background: Salvianolic acid B (SAB) is a major component of Salvia miltiorrhiza root (Danshen), widely used in East/Southeast Asia for centuries to treat cardiovascular diseases. Danshen depside salt, 85% of which is made up of SAB, is approved in China to treat chronic angina. Although clinical observations suggest that Danshen extracts inhibited arterial and venous thrombosis, the exact mechanism has not been adequately elucidated. Objective: To delineate the antithrombotic mechanisms of SAB. Methods: We applied platelet aggregation and coagulation assays, perfusion chambers, and intravital microscopy models. The inhibition kinetics and binding affinity of SAB to thrombin are measured by thrombin enzymatic assays, intrinsic fluorescence spectrophotometry, and isothermal titration calorimetry. We used molecular in silico docking models to predict the interactions of SAB with thrombin. Results: SAB dose-dependently inhibited platelet activation and aggregation induced by thrombin. SAB also reduced platelet aggregation induced by adenosine diphosphate and collagen. SAB attenuated blood coagulation by modifying fibrin network structures and significantly decreased thrombus formation in mouse cremaster arterioles and perfusion chambers. The direct SAB-thrombin interaction was confirmed by enzymatic assays, intrinsic fluorescence spectrophotometry, and isothermal titration calorimetry. Interestingly, SAB shares key structural similarities with the trisubstituted benzimidazole class of thrombin inhibitors, such as dabigatran. Molecular docking models predicted the binding of SAB to the thrombin active site. Conclusion: Our data established SAB as the first herb-derived direct thrombin catalytic site inhibitor, suppressing thrombosis through both thrombin-dependent and thrombin-independent pathways. Purified SAB may be a cost-effective agent for treating arterial and deep vein thrombosis.

Approach to Imaging of Patients Presenting With Acute Coronary Syndrome With No Culprit Lesion Identified at Angiography.

Chest pain is a common chief complaint among patients presenting to the emergency department. However, in the scenario where the clinical presentation is consistent with acute coronary syndrome and no culprit lesions are identified on angiography, clinicians and cardiac imagers should be informed of the differential diagnosis and appropriate imaging modalities used to investigate the potential causes. This review describes an imaging-based algorithm that highlights the diagnostic possibilities, their differentiating imaging features, and the important role of cardiovascular magnetic resonance imaging for narrowing the differential diagnosis.

Cardiac Investigation Trends Among Primary Care Physicians: A Paradigm Shift.

OBJECTIVE: While numerous recent guidelines support coronary computed tomography angiography (CTA) as a first-line test for stable chest pain, it remains underutilized by primary care physicians (PCPs). We aimed to evaluate cardiac investigation ordering practices following education sessions, as well as the total number of downstream tests and time to diagnosis for patients presenting with stable chest pain. METHODS: A retrospective chart review was completed for eligible patients assessed at the Women's College Hospital Family Practice Health Centre between 2017 and 2019 following the education sessions. The outcome measures were first-choice cardiac investigation, additional downstream testing, time from presentation to first investigation, and time to final diagnosis. RESULTS: 419 patients were included in the final analysis (74.70% female; mean age 61 ± 11 years). Coronary CTA requests by PCPs increased between 2017 and 2019 (18 vs 72 tests; P < .0001). When coronary CTA was the first-line test, patients were less likely to receive additional downstream testing when compared to those receiving other first-line investigations (P < .0001). Coronary CTA was associated with longer time to diagnosis than stress echocardiography (47 ± 45 vs 27 ± 36 days; P = .0068) due to limited availability of coronary CTA appointment times. There was no significant difference in time to final diagnosis among the cardiac imaging modalities observed in the cohort (P = .0623). CONCLUSION: Utilization of coronary CTA as the first-line test for stable chest pain increased following our education sessions targeting PCPs. Coronary CTA was associated with less downstream testing compared to other non-invasive cardiac investigations.