Daily Cardiology Research Analysis
Three impactful cardiology papers stand out today: an individual patient data meta-analysis shows that de-escalating to ticagrelor monotherapy after short DAPT in ACS reduces major bleeding without increasing ischemic events; a translational study reveals that the FDA-approved bisphosphonate risedronate structurally corrects a TNNT2 K210del mutation, restoring myocardial function in models of genetic DCM; and an externally validated smartphone photoplethysmography algorithm detects AF/AFL with ~
Summary
Three impactful cardiology papers stand out today: an individual patient data meta-analysis shows that de-escalating to ticagrelor monotherapy after short DAPT in ACS reduces major bleeding without increasing ischemic events; a translational study reveals that the FDA-approved bisphosphonate risedronate structurally corrects a TNNT2 K210del mutation, restoring myocardial function in models of genetic DCM; and an externally validated smartphone photoplethysmography algorithm detects AF/AFL with ~99% accuracy in ambulatory, unsupervised settings.
Research Themes
- Antithrombotic strategy optimization in acute coronary syndromes
- Precision/repurposed therapeutics for genetic cardiomyopathy
- AI-enabled smartphone diagnostics for arrhythmia
Selected Articles
1. An FDA-approved drug structurally and phenotypically corrects the K210del mutation in genetic cardiomyopathy models.
The authors solved the crystal structure of the troponin complex carrying the TNNT2 K210del mutation, revealing S69 distortion in TnC and calcium discoordination. Structure-guided repurposing identified risedronate, which restored the mutant structure, normalized force in K210del patient iPSC-cardiomyocytes, improved calcium sensitivity in skinned muscle, and normalized LVEF in K210del mice.
Impact: This study identifies a precise structural defect in a human DCM mutation and corrects it using an already approved drug, demonstrating a mutation-targeted therapeutic concept with immediate translational potential.
Clinical Implications: While preclinical, these results support clinical exploration of risedronate as a mutation-specific therapy for TNNT2 K210del DCM and provide a generalizable framework for structure-guided drug repurposing in genetic cardiomyopathies.
Key Findings
- K210del in TNNT2 induces an allosteric shift that distorts TnC S69 and disrupts calcium coordination.
- Risedronate cocrystallized with the mutant troponin complex restores S69 configuration and Ca2+ coordination.
- Risedronate normalizes force generation in K210del patient iPSC-derived cardiomyocytes.
- Skinned papillary muscles from K210del mice show improved calcium sensitivity with risedronate.
- Systemic risedronate administration normalizes left ventricular ejection fraction in K210del mice.
Methodological Strengths
- Integrated structural biology with cellular and in vivo functional validation.
- Use of patient-derived iPSC cardiomyocytes and a genetically accurate mouse model.
Limitations
- Findings are mutation-specific (TNNT2 K210del) and may not generalize to other DCM mutations.
- Preclinical study without human clinical trial data; dosing, safety, and efficacy in patients remain unknown.
Future Directions: Phase 1/2 trials to assess safety and pharmacodynamics of risedronate in TNNT2 K210del carriers; expansion of structure-guided screens to other sarcomeric mutations; long-term efficacy and off-target assessments.
Dilated cardiomyopathy (DCM) due to genetic disorders results in decreased myocardial contractility, leading to high morbidity and mortality rates. There are several therapeutic challenges in treating DCM, including poor understanding of the underlying mechanism of impaired myocardial contractility and the difficulty of developing targeted therapies to reverse mutation-specific pathologies. In this report, we focused on K210del, a DCM-causing mutation, due to 3-nucleotide deletion of sarcomeric troponin T (TnnT), resulting in loss of Lysine210. We resolved the crystal structure of the troponin complex carrying the K210del mutation. K210del induced an allosteric shift in the troponin complex resulting in distortion of activation Ca2+-binding domain of troponin C (TnnC) at S69, resulting in calcium discoordination. Next, we adopted a structure-based drug repurposing approach to identify bisphosphonate risedronate as a potential structural corrector for the mutant troponin complex. Cocrystallization of risedronate with the mutant troponin complex restored the normal configuration of S69 and calcium coordination. Risedronate normalized force generation in K210del patient-induced pluripotent stem cell-derived (iPSC-derived) cardiomyocytes and improved calcium sensitivity in skinned papillary muscles isolated from K210del mice. Systemic administration of risedronate to K210del mice normalized left ventricular ejection fraction. Collectively, these results identify the structural basis for decreased calcium sensitivity in K210del and highlight structural and phenotypic correction as a potential therapeutic strategy in genetic cardiomyopathies.
2. De-escalating Dual Antiplatelet Therapy to Ticagrelor Monotherapy in Acute Coronary Syndrome : A Systematic Review and Individual Patient Data Meta-analysis of Randomized Clinical Trials.
Across 9,130 ACS patients in three RCTs, ticagrelor monotherapy after short DAPT reduced major bleeding (BARC 3/5; HR 0.30) without increasing ischemic events (HR 0.85) compared with 12 months of ticagrelor-based DAPT. Benefits were consistent across STEMI, NSTEMI, and unstable angina.
Impact: Provides high-quality, IPD-based evidence supporting DAPT de-escalation to ticagrelor monotherapy after DES in ACS, with clear bleeding reduction and no ischemic penalty, informing guideline updates.
Clinical Implications: Clinicians can consider early transition to ticagrelor monotherapy after a short DAPT course in ACS patients post-DES to reduce major bleeding risk without compromising ischemic protection, tailoring duration to patient risk.
Key Findings
- Individual patient data from 3 RCTs (TICO, T-PASS, ULTIMATE-DAPT) totaling 9,130 ACS patients were analyzed.
- Primary ischemic outcome rates were similar with ticagrelor monotherapy vs. standard DAPT (1.7% vs 2.1%; HR 0.85, 95% CI 0.63–1.16).
- Major bleeding (BARC 3/5) was significantly lower with ticagrelor monotherapy (0.8% vs 2.5%; HR 0.30, 95% CI 0.21–0.45).
- Effects were consistent across STEMI, NSTEMI, and unstable angina subgroups.
- PROSPERO-registered analysis; no external funding reported.
Methodological Strengths
- Individual patient data meta-analysis from randomized trials enhances statistical power and subgroup validity.
- Pre-registered protocol and harmonized endpoints across trials.
Limitations
- Only ticagrelor-based de-escalation was assessed; other P2Y12 strategies not included.
- Trials largely conducted in East Asian populations, potentially limiting global generalizability.
Future Directions: Head-to-head comparisons of alternative de-escalation strategies, incorporation of bleeding/ischemia risk scores for individualized DAPT duration, and validation across diverse global populations.
BACKGROUND: The role of transitioning from short dual antiplatelet therapy (DAPT) to potent P2Y12 inhibitor monotherapy in patients with acute coronary syndrome (ACS) undergoing drug-eluting stent (DES) implantation remains inconclusive. PURPOSE: To compare the effects of de-escalating DAPT to ticagrelor monotherapy versus standard DAPT from randomized clinical trials in patients with ACS. DATA SOURCES: PubMed, EMBASE, Scopus, and ClinicalTrials.gov from inception to 12 December 2024. STUDY SELECTION: Randomized clinical trials comparing de-escalating DAPT to ticagrelor monotherapy versus ticagrelor-based standard DAPT for 12 months, specifically in patients with ACS undergoing DES implantation. DATA EXTRACTION: The coprimary end points were an ischemic end point (composite of death, nonprocedural [spontaneous] myocardial infarction, or stroke) and a bleeding end point (Bleeding Academic Research Consortium types 3 or 5 bleeding). DATA SYNTHESIS: Individual patient data were obtained from 3 trials (TICO [Ticagrelor Monotherapy After 3 Months in the Patients Treated With New Generation Sirolimus-Eluting Stent for Acute Coronary Syndrome], T-PASS [Ticagrelor Monotherapy in Patients Treated With New-Generation Drug-Eluting Stents for Acute Coronary Syndrome], and ULTIMATE-DAPT [Ticagrelor alone versus ticagrelor plus aspirin from month 1 to month 12 after percutaneous coronary intervention in patients with acute coronary syndromes]), including 9130 randomized patients with ACS; 3132 had ST-segment elevation myocardial infarction (STEMI), 3023 had non-STEMI (NSTEMI), and 2975 had unstable angina. The rate of the primary ischemic end point was not different between the ticagrelor monotherapy and standard DAPT groups (1.7% vs. 2.1%; hazard ratio [HR], 0.85 [95% CI, 0.63 to 1.16]). The rate of the primary bleeding end point was lower in the ticagrelor monotherapy group (0.8% vs. 2.5%; HR, 0.30 [CI, 0.21 to 0.45]). These findings were consistent in patients with STEMI, NSTEMI, and unstable angina. LIMITATION: Other de-escalation strategies for modulating antiplatelet therapy were not included. CONCLUSION: In patients with ACS undergoing DES implantation, de-escalating DAPT to ticagrelor monotherapy was associated with a lower risk for major bleeding compared with standard DAPT, without an increase in ischemic events, regardless of the type of ACS. PRIMARY FUNDING SOURCE: None. (PROSPERO: CRD42024565855).
3. External validation of a machine learning-based classification algorithm for ambulatory heart rhythm diagnostics in pericardioversion atrial fibrillation patients using smartphone photoplethysmography: the SMARTBEATS-ALGO study.
In 280 pericardioversion patients generating 18,005 paired smartphone-PPG and single-lead ECG recordings, an SVM-based algorithm achieved 99.7% sensitivity/specificity for AF and ~99.2% for AF/AFL classification in unsupervised ambulatory conditions.
Impact: Demonstrates externally validated, near–diagnostic-grade arrhythmia detection using ubiquitous smartphone sensors, enabling scalable remote rhythm monitoring with minimal manual oversight.
Clinical Implications: Smartphone PPG, coupled with validated ML classification, can reduce reliance on ECG confirmation and manual review in pericardioversion monitoring, potentially improving adherence and access in elderly populations.
Key Findings
- Prospective external validation in 280 patients yielded 18,005 paired PPG–ECG recordings.
- AF classification achieved 99.7% sensitivity, 99.7% specificity, and 99.7% accuracy.
- AF/AFL classification achieved 99.3% sensitivity, 99.1% specificity, and 99.2% accuracy.
- Recordings were obtained in an unsupervised ambulatory setting using standard iPhone 7 hardware.
- Simultaneous single-lead ECG served as the gold standard comparator.
Methodological Strengths
- Simultaneous gold-standard ECG labeling for each PPG event.
- Large number of paired recordings with a prospective external validation cohort.
Limitations
- Generalizability beyond pericardioversion populations and beyond a single smartphone model (iPhone 7) is uncertain.
- Algorithm performance in noisy real-world conditions and across diverse skin tones/devices requires further study.
Future Directions: Evaluate algorithm performance across broader populations and devices, integrate with clinical workflows for automated alerts, and assess health outcomes and cost-effectiveness of PPG-based surveillance.
AIMS: The aim of this study was to perform an external validation of an automatic machine learning (ML) algorithm for heart rhythm diagnostics using smartphone photoplethysmography (PPG) recorded by patients with atrial fibrillation (AF) and atrial flutter (AFL) pericardioversion in an unsupervised ambulatory setting. METHODS AND RESULTS: Patients undergoing cardioversion for AF or AFL performed 1-min heart rhythm recordings pericardioversion at least twice daily for 4-6 weeks, using an iPhone 7 smartphone running a PPG application (CORAI Heart Monitor) simultaneously with a single-lead electrocardiogram (ECG) recording (KardiaMobile). The algorithm uses support vector machines to classify heart rhythm from smartphone-PPG. The algorithm was trained on PPG recordings made by patients in a separate cardioversion cohort. Photoplethysmography recordings in the external validation cohort were analysed by the algorithm. Diagnostic performance was calculated by comparing the heart rhythm classification output to the diagnosis from the simultaneous ECG recordings (gold standard). In total, 460 patients performed 34 097 simultaneous PPG and ECG recordings, divided into 180 patients with 16 092 recordings in the training cohort and 280 patients with 18 005 recordings in the external validation cohort. Algorithmic classification of the PPG recordings in the external validation cohort diagnosed AF with sensitivity, specificity, and accuracy of 99.7%, 99.7% and 99.7%, respectively, and AF/AFL with sensitivity, specificity, and accuracy of 99.3%, 99.1% and 99.2%, respectively. CONCLUSION: A machine learning-based algorithm demonstrated excellent performance in diagnosing atrial fibrillation and atrial flutter from smartphone-PPG recordings in an unsupervised ambulatory setting, minimizing the need for manual review and ECG verification, in elderly cardioversion populations. CLINICAL TRIAL REGISTRATION: Clinicaltrials.gov, NCT04300270.