Daily Cardiology Research Analysis
Analyzed 189 papers and selected 3 impactful papers.
Summary
A phase 3 randomized analysis showed the cardiac myosin inhibitor aficamten outperformed metoprolol across multiple exercise physiology endpoints in obstructive hypertrophic cardiomyopathy. A mechanistic study in Nature Cardiovascular Research demonstrated that selective titin spring cleavage disrupts cardiac mechanical homeostasis, driving heart failure and fibrosis. A JACC Imaging study introduced a CT-derived Morphology-Inflammation-Burden (MIB) score that correlates with invasive plaque vulnerability and predicts adverse cardiac events.
Research Themes
- Myosin inhibition as first-line therapy in obstructive hypertrophic cardiomyopathy
- Sarcomeric mechanics and proteolysis driving heart failure and fibrosis
- Noninvasive coronary plaque vulnerability assessment and risk stratification with CT
Selected Articles
1. Exercise Performance With Aficamten vs Metoprolol in Obstructive Hypertrophic Cardiomyopathy: The MAPLE-HCM Randomized Clinical Trial.
In this prespecified analysis of a phase 3 randomized, active-controlled trial (n=175 randomized; 165 with core-lab validated exercise tests), aficamten improved submaximal VE/VCO2 slope (−2.8), anaerobic threshold (+76 mL/min), peak workload (+8 W), faster VO2 recovery (−11 s), and higher circulatory power versus metoprolol. Large improvements in peak VO2 (≥3.0 mL/kg/min) were more frequent with aficamten (20.5% vs 3.7%), whereas large declines were more common with metoprolol.
Impact: Demonstrates superior exercise adaptation with a myosin inhibitor over β-blockade in oHCM, challenging the long-held first-line status of β-blockers.
Clinical Implications: Supports consideration of aficamten as first-line pharmacotherapy for symptomatic oHCM to improve exercise capacity; may alter guideline recommendations pending hard-outcome data.
Key Findings
- Aficamten reduced submaximal VE/VCO2 slope by −2.8 (95% CI, −4.0 to −1.5; P<.001) vs metoprolol.
- Anaerobic threshold increased by +76 mL/min (95% CI, 41 to 111; P<.001) with aficamten.
- Peak workload improved by +8 W (95% CI, 3 to 13; P=.003) and VO2 recovery was 11 s faster (P<.001).
- Large peak VO2 improvements (≥3.0 mL/kg/min) were more frequent with aficamten (20.5% vs 3.7%); large declines were less frequent (2.4% vs 20.7%).
Methodological Strengths
- Phase 3 randomized, active-controlled, multicenter design with prespecified secondary endpoints.
- Core-laboratory validation of cardiopulmonary exercise tests across 71 international sites.
Limitations
- Prespecified secondary analysis; trial not powered for clinical hard outcomes.
- 24-week duration; excluded atrial fibrillation and patients requiring continued β-blockers or CCBs, limiting generalizability.
Future Directions: Evaluate long-term clinical outcomes (HF hospitalization, mortality), safety, and comparative effectiveness versus other guideline-directed therapies; assess real-world first-line use.
IMPORTANCE: Patients with obstructive hypertrophic cardiomyopathy (oHCM) endure life-altering exercise limitations. Current treatment guidelines recommend β-blockers as first-line therapy primarily based on expert opinion. The Metoprolol vs Aficamten in Patients with Left Ventricular Outflow Tract Obstruction on Exercise Capacity in HCM (MAPLE-HCM) trial characterizes comprehensive exercise response to aficamten monotherapy vs β-blockade (metoprolol). OBJECTIVE: To determine the effect of aficamten compared with metoprolol across all stages of exercise using 16 quantitative measures in individuals with oHCM. DESIGN, SETTING, AND PARTICIPANTS: This was a prespecified secondary analysis of the MAPLE-HCM study, a phase 3, randomized, active-control trial conducted from June 2023 to March 2025 with data analyzed between May and July 2025 at 71 sites in North America, South America, Europe, Israel, and China. Patients with symptomatic oHCM with objective evidence of exercise intolerance (peak oxygen uptake [pVO2] <100% of predicted) were included. Those with a history of atrial fibrillation (paroxysmal or persistent), medical indication for β-blockers or calcium channel blockers prohibiting drug discontinuation, or intolerance or medical contraindication to β-blockers were excluded. INTERVENTION: Randomized 1:1 to titrated aficamten (5-20 mg daily) or matching titrated metoprolol (50-200 mg daily) for 24 weeks.
2. Selective titin cleavage disrupts cardiac mechanical homeostasis to drive heart failure and fibrosis.
Using a titin-spring cleavage knock-in mouse, the authors show that selective titin proteolysis reduces chamber size, impairs ventricular filling, and diminishes restoring forces in cardiomyocytes. Cleavage disrupts integrin and connexin 43 junctions, widens intermyocyte spacing without hypertrophy, activates fibroblasts, remodels extracellular matrix, and leads to decompensated heart failure.
Impact: Reveals a direct mechanistic link between titin proteolysis and heart failure/fibrosis, reframing myocardial injury pathways and identifying potential therapeutic targets upstream of matrix remodeling.
Clinical Implications: Suggests targeting proteases or pathways that mediate titin spring cleavage, and preserving sarcomere-ECM junctional integrity, as potential strategies to prevent or treat HF with fibrosis.
Key Findings
- In vivo selective titin spring cleavage reduced cardiac chamber size and impaired ventricular filling without dilation.
- Cardiomyocytes showed diminished restoring forces and loss of elastic recoil after cleavage.
- Cleavage disrupted integrin linkages and connexin 43 gap junctions, widened intermyocyte space, and activated fibroblasts.
- Extracellular matrix remodeling and fibrosis ensued, culminating in decompensated heart failure.
Methodological Strengths
- Genetic knock-in model enabling controlled titin spring cleavage in vivo.
- Multimodal phenotyping (CMR, echocardiography, microscopy, multi-omics) with cellular mechanics assays.
Limitations
- Preclinical mouse model; human translational validation is needed.
- Specific protease pathways mediating titin cleavage were not fully delineated.
Future Directions: Identify upstream proteases mediating titin cleavage, validate findings in human tissues, and test pharmacologic/genetic interventions to prevent cleavage and fibrosis progression.
Titin, the largest human protein, forms the elastic sarcomeric backbone, providing passive stiffness and length-dependent activation in cardiomyocytes. Whereas titin mutations cause inherited cardiomyopathies, ischemic and chemotherapy-induced injury also provoke proteolytic cleavage of titin's elastic segment. However, the effects of acute titin stiffness loss remain unknown. Here we develop a knock-in mouse enabling in vivo cleavage of cardiac titin springs and use multimodal analysis (cardiac magnetic resonance imaging, echocardiography, microscopy, omics) to show that titin cleavage does not dilate the heart but reduces chamber size and impairs ventricular filling. Mechanical assays of isolated cardiomyocytes reveal diminished restoring forces causing a loss of elastic recoil. In vivo cleavage disrupts junctions, including integrin linkages and connexin 43 gap junctions, widens intermyocyte space without hypertrophy or hyperplasia and drives fibroblast activation, extracellular matrix remodeling and fibrosis. Compensatory mechanisms fail, leading to decompensated heart failure. These findings establish that proteolytic titin cleavage perturbs cardiac mechanical homeostasis, driving disease and matrix stiffening.
3. Integrated Coronary CT Angiography Assessment of Plaque Vulnerability and Clinical Outcomes: The Morphology-Inflammation-Burden (MIB) Score.
Among 438 patients (1,038 plaques) with CTA followed by OCT/IVUS and 31-month median follow-up, high-risk CT plaque features, elevated pericoronary adipose tissue attenuation, and high total plaque burden independently associated with OCT-defined vulnerability. TPB correlated with IVUS percent atheroma volume (r=0.69). A higher MIB score showed stepwise increases in vulnerability and predicted higher rates of cardiac death/ACS/revascularization (15.3% vs 4.4%).
Impact: Provides a practical, noninvasive CT-based composite score linked to invasive vulnerability metrics and outcomes, enabling broader risk stratification without intracoronary imaging.
Clinical Implications: CTA-derived MIB scoring can identify high-risk plaques/patients for intensified prevention, closer follow-up, and potential pre-emptive therapy, reducing reliance on invasive imaging.
Key Findings
- High-risk CT plaque, elevated pericoronary adipose tissue attenuation, and high total plaque burden independently associated with OCT-defined vulnerability.
- Total plaque burden on CT correlated with IVUS percent atheroma volume (r=0.69; P<0.001).
- The MIB score exhibited stepwise increases in vulnerability; highest category exceeded a predicted risk of 90%.
- Patients with ≥1 untreated high-MIB lesion had higher rates of cardiac death/ACS/revascularization (15.3% vs 4.4%; P<0.001).
Methodological Strengths
- Multimodal validation against OCT and IVUS with longitudinal outcome follow-up.
- Quantitative, interpretable CT metrics integrated into a composite score with stepwise risk discrimination.
Limitations
- Observational design with potential selection bias (patients undergoing both CTA and invasive imaging).
- External validation and assessment of management changes based on MIB scoring are needed.
Future Directions: Prospective external validation, integration into clinical decision pathways, and interventional trials testing MIB-guided therapy intensification.
BACKGROUND: Invasive intracoronary imaging represents the gold standard for identifying vulnerable coronary plaques, but it is not suitable for widespread clinical use. Coronary computed tomography angiography (CTA) may offer a noninvasive alternative. OBJECTIVES: This study aims to integrate coronary CTA-derived plaque morphology, pericoronary inflammation, and plaque burden into a unified morphology-inflammation-burden (MIB) score and to evaluate its association with plaque vulnerability and clinical outcomes. METHODS: Patients undergoing coronary CTA followed by optical coherence tomography (OCT) and intravascular ultrasound (IVUS) were followed for a median of 31 months. High-risk plaque, pericoronary adipose tissue attenuation, and total plaque burden (TPB) were quantified and compared with invasive imaging. A vulnerable lesion was defined as ≥2 vulnerability features on OCT. RESULTS: A total of 438 patients (median age 67 years) and 1,038 plaques were included; 45.4% presented with non-ST-segment elevation acute coronary syndrome. High-risk plaque, elevated pericoronary adipose tissue attenuation, and high TPB were independently associated with OCT-defined vulnerability (P < 0.05 for all). TPB correlated with IVUS percent atheroma volume (Pearson's r = 0.69; P < 0.001). The MIB score demonstrated a stepwise increase in vulnerability, exceeding a predicted risk of 90% in the highest category. Vulnerable patients, defined by the presence of ≥1 untreated lesion with a high MIB score, had a significantly higher rate of cardiac death, acute coronary syndrome, or revascularization (15.3% vs 4.4%; P < 0.001). CONCLUSIONS: A coronary CTA-derived MIB score correlates with plaque vulnerability by intracoronary imaging and identifies patients at increased risk for adverse events. These findings support the value of coronary CTA for noninvasive risk stratification in clinical practice. (Massachusetts General Hospital and Tsuchiura Kyodo General Hospital Coronary Imaging Collaboration; NCT04523194).