Daily Cardiology Research Analysis
Three high-impact studies advance cardiology across mechanisms, diagnostics, and therapeutics. A Nature Cardiovascular Research paper identifies a gut microbiota–bile acid–TGR5 axis that suppresses platelet activation and thrombosis, suggesting novel antithrombotic strategies. An individual patient data meta-analysis introduces an AI tool (CoDE-HF) that outperforms fixed natriuretic peptide thresholds for diagnosing acute heart failure, while a randomized, blinded, crossover porcine trial shows
Summary
Three high-impact studies advance cardiology across mechanisms, diagnostics, and therapeutics. A Nature Cardiovascular Research paper identifies a gut microbiota–bile acid–TGR5 axis that suppresses platelet activation and thrombosis, suggesting novel antithrombotic strategies. An individual patient data meta-analysis introduces an AI tool (CoDE-HF) that outperforms fixed natriuretic peptide thresholds for diagnosing acute heart failure, while a randomized, blinded, crossover porcine trial shows 3-hydroxybutyrate increases cardiac output and contractility in cardiogenic shock.
Research Themes
- Microbiome–bile acid signaling modulating thrombosis via platelet TGR5
- AI-enhanced individualized diagnosis of acute heart failure using natriuretic peptides
- Metabolic support therapy (ketones) in cardiogenic shock
Selected Articles
1. The gut microbiota-bile acid-TGR5 axis orchestrates platelet activation and atherothrombosis.
In patients with CAD, serum deoxycholic acid was reduced and Bacteroides vulgatus was underrepresented, implicating disrupted bile acid metabolism. Using TGR5 inhibitors and knockout mice, the authors show DCA suppresses agonist-induced platelet activation and thrombosis via platelet TGR5. Oral DCA, B. vulgatus, and healthy donor stool reduced platelet hyperreactivity and thrombosis in atherosclerotic ApoE-deficient mice.
Impact: This study uncovers a mechanistic microbiome–bile acid–platelet axis and identifies TGR5 as an antithrombotic target, opening microbiota- or bile acid-based strategies to mitigate atherothrombosis.
Clinical Implications: Although preclinical, targeting platelet TGR5 or restoring DCA (e.g., via microbiome or bile acid modulation) could form future adjunct antithrombotic approaches beyond current antiplatelet drugs. Human translational studies are warranted to evaluate efficacy and safety.
Key Findings
- Serum deoxycholic acid (DCA) is reduced and Bacteroides vulgatus is underrepresented in CAD, implicating altered bile acid metabolism.
- DCA inhibits agonist-induced platelet activation and thrombosis through platelet TGR5; pharmacological TGR5 inhibition and genetic knockout abrogate this effect.
- Oral gavage with DCA, B. vulgatus, or healthy human stool suppresses platelet hyperreactivity and thrombosis in atherosclerotic ApoE−/− mice.
Methodological Strengths
- Integrative human observation with mechanistic validation using pharmacologic inhibition and TGR5 knockout mice
- Convergent interventions (bile acid, bacterial species, fecal transplant) demonstrating causality
Limitations
- Human interventional data are lacking; clinical efficacy and safety remain unknown
- Human sample sizes and subgroup characteristics are not detailed in the abstract; generalizability requires confirmation
Future Directions: Conduct early-phase clinical trials of TGR5 agonism or bile acid/microbiome modulation in thrombosis-prone CAD; define dosing, safety, and responder phenotypes; explore interactions with standard antiplatelet regimens.
Gut microbiota-derived bile acids are crucial in the pathogenesis and treatment of metabolic diseases. However, their impact on platelet activation and thrombosis in coronary artery disease (CAD) remains poorly understood. In this study, we observed reduced serum deoxycholic acid (DCA) in patients with CAD and an underrepresentation of Bacteroides vulgatus in the gut microbiota of patients with CAD, affecting DCA metabolism. We used Takeda G-protein-coupled receptor 5 (TGR5) inhibitors and TGR5 knockout mice to show that DCA inhibited agonist-induced platelet activation and thrombosis by interacting with the platelet TGR5. Oral gavage treatments with DCA, B. vulgatus and stool from healthy individuals suppressed platelet hyperreactivity and thrombosis in atherosclerotic ApoE
2. Machine learning to optimize use of natriuretic peptides in the diagnosis of acute heart failure.
Across 14 studies (8,493 BNP; 3,899 MR-proANP), guideline thresholds showed variable performance by subgroup. The machine learning-based CoDE-HF tool, combining peptide levels with clinical variables, achieved excellent discrimination (AUC ~0.91–0.93), identified large low- and high-probability subsets with NPV ~98.5% and PPV ~75–79%, and maintained calibration across subgroups.
Impact: Transitions diagnostic practice from fixed cutoffs to individualized probabilities, potentially improving ED triage and reducing misclassification in acute heart failure.
Clinical Implications: CoDE-HF can guide rule-in/rule-out decisions by integrating natriuretic peptides with clinical context, identifying low- and high-probability patients with high NPV/PPV. Implementation studies are needed to assess workflow integration, equity, and impact on outcomes.
Key Findings
- Guideline thresholds for BNP (100 pg/mL) and MR-proANP (120 pmol/L) yielded NPV 93.6%/95.6% and PPV 68.8%/64.8%, with significant subgroup heterogeneity.
- CoDE-HF achieved AUC 0.914 (BNP) and 0.929 (MR-proANP), with good calibration (Brier 0.110/0.094).
- CoDE-HF identified 30–48% as low probability (NPV 98.5%) and 28–30% as high probability (PPV 75–79%), consistent across subgroups.
Methodological Strengths
- Individual patient data meta-analysis across 14 studies from 12 countries with external validation
- Pre-registered protocol (PROSPERO) and robust calibration/discrimination metrics
Limitations
- Prospective clinical impact and workflow integration not yet tested in randomized implementation trials
- Model performance may depend on availability/quality of clinical variables and may require EHR integration
Future Directions: Prospective, multicenter implementation studies to assess clinical utility, health equity, and outcome impact; evaluation in patients with prior heart failure and diverse settings; regulatory and EHR integration.
AIMS: B-type natriuretic peptide (BNP) and mid-regional pro-atrial natriuretic peptide (MR-proANP) testing are guideline-recommended to aid in the diagnosis of acute heart failure. Nevertheless, the diagnostic performance of these biomarkers is uncertain. METHODS AND RESULTS: We performed a systematic review and individual patient-level data meta-analysis to evaluate the diagnostic performance of BNP and MR-proANP. We subsequently developed and externally validated a decision-support tool called CoDE-HF that combines natriuretic peptide concentrations with clinical variables using machine learning to report the probability of acute heart failure. Fourteen studies from 12 countries provided individual patient-level data in 8493 patients for BNP and 3899 patients for MR-proANP, in whom, 48.3% (4105/8493) and 41.3% (1611/3899) had an adjudicated diagnosis of acute heart failure, respectively. The negative predictive value (NPV) of guideline-recommended thresholds for BNP (100 pg/mL) and MR-proANP (120 pmol/L) was 93.6% (95% confidence interval 88.4-96.6%) and 95.6% (92.2-97.6%), respectively, whilst the positive predictive value (PPV) was 68.8% (62.9-74.2%) and 64.8% (56.3-72.5%). Significant heterogeneity in the performance of these thresholds was observed across important subgroups. CoDE-HF was well calibrated with excellent discrimination in those without prior acute heart failure for both BNP and MR-proANP [area under the curve of 0.914 (0.906-0.921) and 0.929 (0.919-0.939), and Brier scores of 0.110 and 0.094, respectively]. CoDE-HF with BNP and MR-proANP identified 30% and 48% as low-probability [NPV of 98.5% (97.1-99.3%) and 98.5% (97.7-99.0%)], and 30% and 28% as high-probability [PPV of 78.6% (70.4-85.0%) and 75.1% (70.9-78.9%)], respectively, and performed consistently across subgroups. CONCLUSION: The diagnostic performance of guideline-recommended BNP and MR-proANP thresholds for acute heart failure varied significantly across patient subgroups. A decision-support tool that combines natriuretic peptides and clinical variables was more accurate and supports more individualized diagnosis. STUDY REGISTRATION: PROSPERO number, CRD42019159407.
3. The ketone body 3-hydroxybutyrate increases cardiac output and cardiac contractility in a porcine model of cardiogenic shock: a randomized, blinded, crossover trial.
In a randomized, assessor-blinded crossover study in 16 pigs with induced cardiogenic shock, infusion of 3-hydroxybutyrate increased cardiac output and cardiac contractility, indicating favorable cardiovascular and cardiometabolic effects during shock.
Impact: Demonstrates a metabolically targeted, readily translatable intervention that augments hemodynamics in cardiogenic shock, a condition with few effective medical therapies.
Clinical Implications: If replicated in humans, ketone supplementation could serve as an adjunct to mechanical and vasoactive support in cardiogenic shock to improve perfusion while definitive care is provided. Safety, dosing, and metabolic effects require rigorous clinical testing.
Key Findings
- Randomized, assessor-blinded, crossover design in 16 pigs with left main coronary artery microsphere-induced cardiogenic shock.
- 3-hydroxybutyrate increased cardiac output and cardiac contractility during cardiogenic shock.
- Findings indicate favorable cardiometabolic effects of ketone therapy under shock conditions.
Methodological Strengths
- Randomized, assessor-blinded, crossover large-animal model closely mimicking ischemic cardiogenic shock
- Physiologic endpoints directly relevant to hemodynamic support
Limitations
- Preclinical animal study with small sample size and short-term hemodynamic outcomes
- Lack of survival and safety data and absence of human validation
Future Directions: Early-phase human trials to evaluate safety, dosing, metabolic effects, and hemodynamic impact of ketone infusions in cardiogenic shock; comparative studies versus standard vasoactive regimens; assessment of organ perfusion and outcomes.
Cardiogenic shock (CS) is characterized by reduced cardiac output (CO), reduced end-organ perfusion, and high mortality. Medical therapies have failed to improve survival. The ketone body 3-hydroxybutyrate (3-OHB) enhances cardiac function in heart failure and CS. We aimed to elucidate the cardiovascular and cardiometabolic effects of 3-OHB treatment during CS. In a randomized, assessor-blinded crossover design, we studied 16 female pigs (60 kg, 5 months of age). CS was induced by left main coronary artery microsphere injections. Predefined criteria for CS were a 30% reduction in CO or mixed venous saturation (SvO