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Masri A, Cardoso RN, Abraham TP, Claggett BL, Coats CJ, Hegde SM, Kulac IJ, Lee MMY, Maron MS, Merkely B, Michels M, Olivotto I, Oreziak A, Jacoby DL, Heitner SB, Kupfer S, Malik FI, Meng L, Solomon SD, Wohltman A, Kwong RY, Kramer CM. Effect of Aficamten on Cardiac Structure and Function in Obstructive Hypertrophic Cardiomyopathy: SEQUOIA-HCM CMR Substudy. J Am Coll Cardiol 2024:S0735-1097(24)08167-1. [PMID: 39217563 DOI: 10.1016/j.jacc.2024.08.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2024] [Revised: 08/08/2024] [Accepted: 08/09/2024] [Indexed: 09/04/2024]
Abstract
BACKGROUND Obstructive hypertrophic cardiomyopathy (oHCM) is characterized by left ventricular (LV) hypertrophy, LV outflow tract obstruction, and left atrial dilation, which can be associated with progressive heart failure, atrial fibrillation, and stroke. Aficamten is a next-in-class cardiac myosin inhibitor that reduces outflow tract obstruction by modulating cardiac contractility, with the potential to reverse pathological remodeling and, in turn, reduce cardiovascular events. OBJECTIVES This study sought to investigate the effect of aficamten on cardiac remodeling compared with placebo using cardiovascular magnetic resonance (CMR) and its association with key clinical endpoints in the SEQUOIA-HCM (Safety, Efficacy, and Quantitative Understanding of Obstruction Impact of Aficamten in HCM) CMR substudy. METHODS SEQUOIA-HCM was a phase 3 double-blind, placebo-controlled trial for adults with symptomatic oHCM who were randomized 1:1 to 24 weeks of aficamten (dose range: 5-20 mg) or placebo. Eligible participants were offered enrollment in the CMR substudy with studies performed at baseline and week 24. Image analysis was performed in a blinded fashion by a core laboratory. RESULTS Of the 282 randomized patients, 57 (20%) participated in the substudy, and of those, 50 (88%) completed both baseline and week 24 CMR. Baseline characteristics of the CMR cohort were similar to the overall study population. Of these 50 patients, 21 received aficamten and 29 received placebo. Relative to placebo, patients receiving aficamten demonstrated significant reductions (Δ least-squares mean) in LV mass index (-15 g/m2; 95% CI: -25 to -6 g/m2; P = 0.001), maximal LV wall thickness (-2.1 mm; 95% CI: -3.1 to -1.1 mm; P < 0.001), left atrial volume index (-13 mL/m2; 95% CI: -19 to -7 mL/m2; P < 0.001), native T1 relaxation time (-37 ms; 95% CI: -69 to -5 ms; P = 0.026), indexed extracellular volume fraction (-3.9 g/m2; 95% CI: -7.0 to -0.9 g/m2; P = 0.014), and indexed myocyte mass (-14 g/m2; 95% CI: -23 to -4 g/m2; P = 0.004), while there were no significant changes in LV chamber volumes, LV replacement fibrosis (late gadolinium enhancement mass -0.7 g; 95% CI: -2.9 to 1.6 g; P = 0.54), or extracellular volume (0.7%; 95% CI: -2.2% to 3.6%; P = 0.61). CONCLUSIONS The CMR substudy of SEQUOIA-HCM demonstrated that treatment with aficamten relative to placebo for 24 weeks resulted in favorable cardiac remodeling. These changes, particularly with regard to LV mass, wall thickness, and left atrial size, could potentially lead to reduced cardiovascular events including heart failure and atrial fibrillation with longer follow-up. (Phase 3 Trial to Evaluate the Efficacy and Safety of Aficamten Compared to Placebo in Adults With Symptomatic oHCM [SEQUOIA-HCM]; NCT05186818).
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Affiliation(s)
- Ahmad Masri
- Oregon Health and Science University, Portland, Oregon, USA.
| | - Rhanderson N Cardoso
- Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | | | - Brian L Claggett
- Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Caroline J Coats
- School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow, United Kingdom
| | - Sheila M Hegde
- Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Ian J Kulac
- Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Matthew M Y Lee
- School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow, United Kingdom
| | - Martin S Maron
- Lahey Hospital and Medical Center, Burlington, Massachusetts, USA
| | - Bela Merkely
- Heart and Vascular Center, Semmelweis University, Budapest, Hungary
| | - Michelle Michels
- Erasmus University Medical Center, Cardiovascular Institute, Thoraxcenter, Department of Cardiology, Rotterdam, the Netherlands
| | - Iacopo Olivotto
- Meyer Children's Hospital, Istituto di Ricovero e Cura a Carattere Scientifico, Florence, Italy
| | | | | | | | | | - Fady I Malik
- Cytokinetics, South San Francisco, California, USA
| | - Lisa Meng
- Cytokinetics, South San Francisco, California, USA
| | | | - Amy Wohltman
- Cytokinetics, South San Francisco, California, USA
| | - Raymond Y Kwong
- Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Christopher M Kramer
- Cardiovascular Division, Department of Medicine, University of Virginia Health, Charlottesville, Virginia, USA
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Coleman JA, Doste R, Ashkir Z, Coppini R, Sachetto R, Watkins H, Raman B, Bueno-Orovio A. Mechanisms of ischaemia-induced arrhythmias in hypertrophic cardiomyopathy: a large-scale computational study. Cardiovasc Res 2024; 120:914-926. [PMID: 38646743 PMCID: PMC11218689 DOI: 10.1093/cvr/cvae086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 01/31/2024] [Accepted: 03/17/2024] [Indexed: 04/23/2024] Open
Abstract
AIMS Lethal arrhythmias in hypertrophic cardiomyopathy (HCM) are widely attributed to myocardial ischaemia and fibrosis. How these factors modulate arrhythmic risk remains largely unknown, especially as invasive mapping protocols are not routinely used in these patients. By leveraging multiscale digital twin technologies, we aim to investigate ischaemic mechanisms of increased arrhythmic risk in HCM. METHODS AND RESULTS Computational models of human HCM cardiomyocytes, tissue, and ventricles were used to simulate outcomes of Phase 1A acute myocardial ischaemia. Cellular response predictions were validated with patch-clamp studies of human HCM cardiomyocytes (n = 12 cells, N = 5 patients). Ventricular simulations were informed by typical distributions of subendocardial/transmural ischaemia as analysed in perfusion scans (N = 28 patients). S1-S2 pacing protocols were used to quantify arrhythmic risk for scenarios in which regions of septal obstructive hypertrophy were affected by (i) ischaemia, (ii) ischaemia and impaired repolarization, and (iii) ischaemia, impaired repolarization, and diffuse fibrosis. HCM cardiomyocytes exhibited enhanced action potential and abnormal effective refractory period shortening to ischaemic insults. Analysis of ∼75 000 re-entry induction cases revealed that the abnormal HCM cellular response enabled establishment of arrhythmia at milder ischaemia than otherwise possible in healthy myocardium, due to larger refractoriness gradients that promoted conduction block. Arrhythmias were more easily sustained in transmural than subendocardial ischaemia. Mechanisms of ischaemia-fibrosis interaction were strongly electrophysiology dependent. Fibrosis enabled asymmetric re-entry patterns and break-up into sustained ventricular tachycardia. CONCLUSION HCM ventricles exhibited an increased risk to non-sustained and sustained re-entry, largely dominated by an impaired cellular response and deleterious interactions with the diffuse fibrotic substrate.
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Affiliation(s)
- James A Coleman
- Department of Computer Science, University of Oxford, Oxford, UK
| | - Ruben Doste
- Department of Computer Science, University of Oxford, Oxford, UK
| | - Zakariye Ashkir
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Radcliffe Department of Medicine, Division of Cardiovascular Medicine, University of Oxford, Oxford, UK
| | - Raffaele Coppini
- Department of NeuroFarBa, University of Florence, Florence, Italy
| | - Rafael Sachetto
- Department of Computer Science, Federal University of São João del-Rei, São João del-Rei, Minas Gerais, Brazil
| | - Hugh Watkins
- Radcliffe Department of Medicine, Division of Cardiovascular Medicine, University of Oxford, Oxford, UK
| | - Betty Raman
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Radcliffe Department of Medicine, Division of Cardiovascular Medicine, University of Oxford, Oxford, UK
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Coleman JA, Doste R, Beltrami M, Argirò A, Coppini R, Olivotto I, Raman B, Bueno-Orovio A. Effects of ranolazine on the arrhythmic substrate in hypertrophic cardiomyopathy. Front Pharmacol 2024; 15:1379236. [PMID: 38659580 PMCID: PMC11039821 DOI: 10.3389/fphar.2024.1379236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Accepted: 03/25/2024] [Indexed: 04/26/2024] Open
Abstract
Introduction: Hypertrophic cardiomyopathy (HCM) is a leading cause of lethal arrhythmias in the young. Although the arrhythmic substrate has been hypothesised to be amenable to late Na+ block with ranolazine, the specific mechanisms are not fully understood. Therefore, this study aimed to investigate the substrate mechanisms of safety and antiarrhythmic efficacy of ranolazine in HCM. Methods: Computational models of human tissue and ventricles were used to simulate the electrophysiological behaviour of diseased HCM myocardium for variable degrees of repolarisation impairment, validated against in vitro and clinical recordings. S1-S2 pacing protocols were used to quantify arrhythmic risk in scenarios of (i) untreated HCM-remodelled myocardium and (ii) myocardium treated with 3µM, 6µM and 10µM ranolazine, for variable repolarisation heterogeneity sizes and pacing rates. ECGs were derived from biventricular simulations to identify ECG biomarkers linked to antiarrhythmic effects. Results: 10µM ranolazine given to models manifesting ventricular tachycardia (VT) at baseline led to a 40% reduction in number of VT episodes on pooled analysis of >40,000 re-entry inducibility simulations. Antiarrhythmic efficacy and safety were dependent on the degree of repolarisation impairment, with optimal benefit in models with maximum JTc interval <370 ms. Ranolazine increased risk of VT only in models with severe-extreme repolarisation impairment. Conclusion: Ranolazine efficacy and safety may be critically dependent upon the degree of repolarisation impairment in HCM. For moderate repolarisation impairment, reductions in refractoriness heterogeneity by ranolazine may prevent conduction blocks and re-entry. With severe-extreme disease substrates, reductions of the refractory period can increase re-entry sustainability.
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Affiliation(s)
- James A. Coleman
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Ruben Doste
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Matteo Beltrami
- Cardiomyopathy Unit, Careggi University Hospital, Florence, Italy
| | - Alessia Argirò
- Cardiomyopathy Unit, Careggi University Hospital, Florence, Italy
| | - Raffaele Coppini
- Department of NeuroFarBa, University of Florence, Florence, Italy
| | - Iacopo Olivotto
- Cardiomyopathy Unit, Careggi University Hospital, Florence, Italy
- Meyer Children’s Hospital IRCCS, Florence, Italy
| | - Betty Raman
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Radcliffe Department of Medicine, Division of Cardiovascular Medicine, University of Oxford, Oxford, United Kingdom
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Coleman JA, Doste R, Beltrami M, Coppini R, Olivotto I, Raman B, Bueno-Orovio A. Electrophysiological mechanisms underlying T wave pseudonormalisation on stress ECGs in hypertrophic cardiomyopathy. Comput Biol Med 2024; 169:107829. [PMID: 38096763 DOI: 10.1016/j.compbiomed.2023.107829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 11/09/2023] [Accepted: 12/04/2023] [Indexed: 02/08/2024]
Abstract
BACKGROUND Pseudonormal T waves may be detected on stress electrocardiograms (ECGs) in hypertrophic cardiomyopathy (HCM). Either myocardial ischaemia or purely exercise-induced changes have been hypothesised to contribute to this phenomenon, but the precise electrophysiological mechanisms remain unknown. METHODS Computational models of human HCM ventricles (n = 20) with apical and asymmetric septal hypertrophy phenotypes with variable severities of repolarisation impairment were used to investigate the effects of acute myocardial ischaemia on ECGs with T wave inversions at baseline. Virtual 12-lead ECGs were derived from a total of 520 biventricular simulations, for cases with regionally ischaemic K+ accumulation in hypertrophied segments, global exercise-induced serum K+ increases, and/or increased pacing frequency, to analyse effects on ECG biomarkers including ST segments, T wave amplitudes, and QT intervals. RESULTS Regional ischaemic K+ accumulation had a greater impact on T wave pseudonormalisation than exercise-induced serum K+ increases, due to larger reductions in repolarisation gradients. Increases in serum K+ and pacing rate partially corrected T waves in some anatomical and electrophysiological phenotypes. T wave morphology was more sensitive than ST segment elevation to regional K+ increases, suggesting that T wave pseudonormalisation may sometimes be an early, or the only, ECG feature of myocardial ischaemia in HCM. CONCLUSIONS Ischaemia-induced T wave pseudonormalisation can occur on stress ECG testing in HCM before significant ST segment changes. Some anatomical and electrophysiological phenotypes may enable T wave pseudonormalisation due to exercise-induced increased serum K+ and pacing rate. Consideration of dynamic T wave abnormalities could improve the detection of myocardial ischaemia in HCM.
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Affiliation(s)
- James A Coleman
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Ruben Doste
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Matteo Beltrami
- Cardiomyopathy Unit, Careggi University Hospital, Florence, Italy
| | - Raffaele Coppini
- Department of NeuroFarBa, University of Florence, Florence, Italy
| | - Iacopo Olivotto
- Cardiomyopathy Unit, Careggi University Hospital, Florence, Italy; Meyer Children's Hospital IRCCS, Florence, Italy
| | - Betty Raman
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Radcliffe Department of Medicine, Division of Cardiovascular Medicine, University of Oxford, Oxford, United Kingdom
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