Atrial Appendage Micrograft Transplants to Assist Heart Repair After Cardiac Surgery (AAMS2)

Atrial Appendage Micrograft Transplantation in Conjunction With Cardiac Surgery-the AAMS2 Randomized Controlled Trial

Ischemic heart disease (IHD) leads the global mortality statistics. Atherosclerotic plaques in coronary arteries hallmark IHD, drive hypoxia, and may rupture to result in myocardial infarction (MI) and death of contractile cardiac muscle, which is eventually replaced by a scar. Depending on the extent of the damage, dysbalanced cardiac workload often leads to emergence of heart failure (HF). The atrial appendages, enriched with active endocrine and paracrine cardiac cells, has been characterized to contain cells promising in stimulating cardiac regenerative healing. In this AAMS2 randomized controlled and double-blinded trial, we use the patient's own tissue from the right atrial appendage (RAA) for therapy. A piece from the RAA can be safely harvested upon the set-up of the heart and lung machine at the beginning of coronary artery bypass (CABG) surgery. In the AAMS2 trial, a piece of the RAA tissue is processed and utilized as epicardially transplanted atrial appendage micrografts (AAMs) for CABG-support therapy. In our preclinical evaluation, epicardial AAMs transplantation after MI attenuated scarring and improved cardiac function. Proteomics suggested an AAMs-induced glycolytic metabolism, a process associated with an increased regenerative capacity of myocardium. In an open-label clinical trial, we have demonstrated the safety and feasibility of AAMs therapy. Moreover, as this study suggested increased thickness of the viable myocardium in the scarred area, it also provided the first indication of therapeutic benefit. Based on randomization with estimated enrolment of a total of 50 patients with 1:1 group allocation ratio, the piece of RAA tissue is either perioperatively processed to AAMs or cryostored. The AAMs, embedded in a fibrin matrix gel, are placed on an extracellular matrix sheet (ECM), which is then epicardially sutured in place. The location is determined by preoperative late gadolinium enhancement cardiac magnetic resonance imaging (LGE-CMRI) to pinpoint the ischemic scar. Study blood samples, transthoracic echocardiography (TTE), and LGE-CMRI are performed before and at 6-month follow-up after the surgery. The trial's primary endpoints focus on changes in cardiac fibrosis as evaluated by LGE-CMRI and circulating levels of N-terminal prohormone of brain natriuretic peptide (NT-proBNP). Secondary endpoints center on other efficacy parameters, as well as both safety and feasibility of the therapy.

BACKGROUND AND SIGNIFICANCE Globally, each year 17.9 million people die of cardiovascular diseases. Ischemic heart disease (IHD) is the cause in half of these cases, thus making it the global leading single cause of death [GBD 2017]. While 126.5 million patients suffer from IHD worldwide, in Europe 30.3 million patients are afflicted [Timmis 2018]. IHD is hallmarked by progressively enlarging atherosclerotic coronary plaques. These disease hotspots not only drive myocardial hypoxia, cardiomyocyte hibernation, apoptosis and interstitial fibrosis but are prone for erosion and rupture. Plaque rupture forcefully activates the hemostatic system resulting in thrombotic coronary occlusion, myocardial infarction (MI), and death of cardiac tissue. Due to improved acute care, the patients increasingly survive the acute phase, and the site of injury eventually gets replaced by a scar that typically restricts the filling and pumping of the heart [Cohn 2000]. Depending on the extent of injury and the resulting scar, eventually the increased workload leads to adverse remodeling and emergence of heart failure (HF), an irreversible and incapacitating clinical syndrome with poor prognosis [Taylor 2017, Cohn 2000]. HF due to an ischemic etiology has been reported to vary from 29% to 45% [Groenewegen 2020]. For instance, a recent meta-analysis suggests the "all-type" HF prevalence, including the previously unrecognized cases via population-based echocardiographic screening, to be as high as 11.8% among general population aged above 65 years [van Riet 2016]. CABG surgery is the preferred revascularization method for patients with severe progressed IHD [Rihal 2003]. In Europe, more than 245,000 CABG surgeries were carried out in 2016 [Eurostat 2015]. Regardless of age, CABG surgery has been shown to have an overall beneficial effect on ischemic symptoms and mortality [Freitas 2019]. Cardiac healing by regeneration rather than scarring could tilt the IHD with its complications towards an increasingly manageable, even curable, disease. While the hearts of some vertebrates heal by regeneration throughout their lifespan, in rodents this capacity is limited to the first week of life [Cutie 2021]. Very early in life, also the human heart seems to possess capacity to regenerate after ischemia [Haubner 2016]. It has proved complex to activate cardiac regenerative repair in adult human heart. Many stem, progenitor and differentiated cells have been tested in this regard [Cambria 2017]. While these investigations have provided promising results, the therapies remain complex and costly, highlighting the need for more clinically straightforward approaches. Cells derived from atrial appendages have been shown to be capable of stimulating regenerative cardiac healing in the context of ischemic cardiac damage [Koninckx 2013, Detert 2018, Evens 2021]. As positioned by the European Society of Cardiology, many tissue-engineered approaches, including epicardial extracellular matrix (ECM) patch transplantation, are highlighted as promising future therapies for ischemic HF [Madonna 2019]. These approaches could improve the local persistence and viability of the co-transplanted cells-a major obstacle identified in previous studies. GENERAL CONCEPT We use the patient's own heart tissue from the right atrial appendage for therapy. Neither the left nor the right atrial appendage (LAA and RAA, respectively) directly contribute to the heart's pumping function. A piece of the RAA can be safely harvested upon insertion of the right atrial cannula during the set-up of the heart and lung machine at the beginning of CABG [Lampinen 2017, Nummi 2017, Nummi 2021]. In the AAMS2 trial, a piece of the RAA tissue is used as epicardially transplanted, patch-encased, and mechanically expanded atrial appendage micrografts (AAMs). This therapy can be administered during single CABG surgery. PREVIOUS RESULTS In a preclinical mouse model of MI and HF, the effects of epicardial AAMs-patches were compared to acellular ECM patches. The results demonstrated myocardial tissue protection, attenuated scarring, and retained cardiac function [Xie 2020]. Further, mass-spectrometry-based quantitative proteomics demonstrated widespread regenerative and cardioprotective effects in the myocardium, including decreased oxidative stress and AAMs-mediated induction of myocardial glycolytic metabolism, a process associated with an increased regenerative capacity of myocardium [Lalowski 2018, Nakada 2017, Kimura 2015, Puente 2014]. The AAMs-patch therapy has proceeded to clinical use. Following the first-in-man application of AAMs [Nummi 2019], the safety and feasibility of the epicardial AAMs transplantation during CABG was recently confirmed [Nummi 2021]. Moreover, as this study suggested increased thickness of the viable myocardium in the scar zone, it provided the first indication of therapeutic benefit [Nummi 2021]. OBJECTIVES AND OVERVIEW This AAMS2 randomized double-blinded and controlled trial evaluates the effect of epicardially transplanted AAMs as an adjuvant therapy to CABG surgery. The trial's primary endpoints are changes in cardiac function and structure as evaluated using late gadolinium enhancement cardiac magnetic resonance imaging (LGE-CMRI) at 6-month follow-up after surgery as compared to preoperative LGE-CMRI. The trial enrolls 50 patients in a 1:1 group allocation ratio to the study groups (CABG or AAMs patch with CABG). Autologous RAA tissue is harvested from the RAA during CABG from all participants and based on randomization, the piece of RAA tissue is either processed to AAMs perioperatively or cryostored for biochemical analyses. The AAMs, embedded in fibrin matrix gel, are placed on an ECM sheet, which is then epicardially sutured in place. To pinpoint the ischemic scar area as the epicardial transplantation site, LGE-CMRI is done preoperatively. Study blood samples are collected preoperatively as well as at 3- and 6-month follow-up after surgery. Transthoracic echocardiography (TTE), LGE-CMRI, symptom-scaling measures, and 6-minute walking test (6MWT) are performed preoperatively and at the 6-month follow-up. METHODS Patient selection, enrolment, ethics, and timeline-The patients meeting the eligibility and exclusion criteria, as evaluated by a cardiologist, are selected from the hospital's list of elective cardiac surgeries. The patients' medication is optimized according to the current guidelines by the treating cardiologist. The usual waiting time on the list ranges between 2 and 8 weeks. This time allows medication changes to take effect before surgery. Later, the recruited patients are called for a clinical control visit (denoted as the 3-month follow-up) and a dedicated trial visit (at 6-8 months postoperatively, denoted as the 6-month follow-up). All patients are provided with information describing the trial. Before a subject undergoes any study procedure, an informed consent discussion will be conducted and written informed consent to participate is required. The trial will be conducted following the Declaration of Helsinki on Ethical Principles for Medical Research Involving Human Subjects [World Medical Association 2013]. The study has been approved by the Ethics Committee of Hospital District of Helsinki and Uusimaa (HUS; Dnr. HUS/12322/2022). The estimated start of the patient recruitment is December 2022 with an estimated full study completion date on December 2025. The participant is excluded from the trial (screening failure), if after optimization of medications, a visible scar cannot be identified and left ventricular ejection fraction (LVEF) is ≥50% in preoperative LGE-CMRI. This applies also if the LGE-CMRI has not been performed prior to CABG. Endpoints-The trial endpoints are listed in a separate section. The primary endpoints focus on changes in cardiac fibrosis as evaluated by LGE-CMRI and circulating levels of N-terminal prohormone of brain natriuretic peptide (NT-proBNP). The secondary endpoints center on other efficacy parameters as well as both safety and feasibility of the therapy. Randomization and blinding-Patients are randomized into CABG or AAMs groups using sex-stratified block randomization via the openly available online tool at www.sealedenvelope.com with block sizes 2 and 4, and stratification according to sex (female, male). Randomization is carried out by the University of Helsinki (person-in-charge docent Esko Kankuri). Running-numbered sealed envelopes with the randomized allocation information are handed out to the study nurse, who opens each respective envelope at the beginning of each patient's surgery. The study nurse oversees the allocation in a double-blinded manner, where the patient and the evaluating cardiologist and radiologists remain blinded to the study group allocation. Given the nature of the treatment (transplant vs. no transplant) it is impossible to blind the operating surgeon or the study nurse to the allocations. All LGE-CMRI and TTE measurements as well as laboratory analyses are done by researchers blinded to the group allocations. Preparation and administration of atrial appendage micrografts-A piece of the RAA is harvested at the beginning of cardiac surgery upon right atrial cannulation. The RAA tissue is weighed and mechanically processed into micrografts as previously described [Lampinen 2017, Nummi 2017, Nummi 2021] by using the Rigeneracon blade (Rigenera-system, HBW s.r.l., Turin, Italy). Dedicated CE-marked instrumentation kits to support tissue processing in the operating room are obtained from EpiHeart Oy (Helsinki, Finland). The micrografts are spread onto a pericardial matrix sheet (Equine Pericardium Patch, Autotissue GmbH, Berlin, Germany) and are embedded in a small amount of diluted fibrin tissue glue (Tisseel, Baxter AG, Vienna, Austria). The AAMs-patch is maintained cooled (+6 - +8C), covered, and sterile when waiting for transplantation. General data protection regulation-The data collected during the trial will fulfil EU regulations for personal health data protection, including General Data Protection Regulation (GDPR). Blood samples-A blood sample for NT-pro-BNP measurement, a gold standard biomarker for HF evaluation [McKie 2016], is collected preoperatively and at both 3-month and 6-month follow-ups. In addition, the AAMS2 trial assesses blood, plasma, and RAA tissue samples for their contained RNA transcripts with a novel focus on their post-transcriptional modifications, as previously described [Sikorski 2021, Sikorski 2022]. However, to ensure adequate yield of native RNA, instead of collecting 3 mL x 5 of TEMPUS(TM) RNA-stabilized blood per visit, 3 mL x 8 is collected. These modifications comprise a biologic frontier in genetics that is unveiling a key contributor and regulator of many cellular functions and pathophysiologic conditions, also IHD and ischemic HF [Qin 2021, Sikorski 2022]. As the information regarding blood epitranscriptomics in human IHD and HF remains scarce [Sikorski 2022], the AAMS2 trial aims to provide insight into the AAMs-treatment-induced alterations in the blood epitranscriptomes. Especially, the focus is in the two most common modifications, N6-methyladenosine (m6A) and adenosine-to-inosine (A-to-I) editing. RAA tissue samples-The removed piece of RAA tissue from the control group is collected as a sample for biochemical analyses. The piece of RAA tissue will be divided in two and stored (RNAlater or formaldehyde-ethanol) for subsequent epitranscriptomics-targeted evaluations as previously described [Sikorski 2021]. Echocardiography-All participants are assessed with electrocardiogram and TTE preoperatively and at 6-month follow-up postoperatively. The TTE recordings are performed with designated cardiologists. These recordings include both anatomical and functional assessments of ventricles, atria and valves. An especial focus is granted during preoperative TTE, prior to the above-described RAA sample collection for AAMs, to the atrial appendages and the atria proper for anatomic characterization. Moreover, the presence or absence of pericardial effusion, thrombus and aneurysm is recorded. Perfusion anesthesiologist will perform transesophageal echocardiography (TEE) in the operating room during anesthesia to evaluate both left and right atrial appendages for blood flow velocities, possible sludge and thrombus before CABG. Late gadolinium enhancement cardiac magnetic resonance imaging (LGE-CMRI)-A whole body 1.5-T MRI scanner (Siemens Sola or Avanto-fit, Siemens AG, Erlangen, Germany) is used for LGE-CMRI image acquisition. Cardiac structure and function are evaluated with a standardized LGE-CMRI protocol using electrocardiogram and respiratory gating. Short-axis cine images are used for left and right ventricular volumetric measurements. Myocardial contractility is evaluated using longitudinal, circumferential, and radial strain measurements from short- and long-axis cine images. LGE is assessed to measure infarction volume and mass using 5-SD semiautomatic gain estimate, as previously suggested for semiautomatic thresholding for infarction detection [Schulz-Menger 2020]. Image post-processing is performed with Medis Suite software (Medis Medical Imaging Systems, Leiden, The Netherlands) with QMass and QStrain applications. Quality of life assessment-Health-related quality of life (HRQoL) is measured using the RAND36 (SF36) short form questionnaire [Hays 2001]. The questionnaire is standardized with specified mean and standard deviation values for eight dimensions that range from physical functioning and subjective feeling of vitality and health to bodily pain. The obtained scores are compared to a Finnish cohort with any chronic disease. Also, a subject's symptom-evaluation is performed for the two cardinal symptoms of IHD and HF, angina pectoris and exertional dyspnea, with standardized classification systems developed by the Canadian Cardiovascular Society (CCS) and the New York Heart Association (NYHA), respectively [Campeau 1976, Russell 2009]. Finally, a six-minute walking test (6MWT) is assessed to gain objective morbidity measures [Bittner 1993]. All these parameters are assessed both preoperatively and at the 6-month follow-up visit postoperatively. NYHA and CCS classes are also recorded at 3-month clinical follow-up. Statistical analyses-Power analysis was carried out using SAS 9.4 TS Level 1M4 software (SAS Institute Inc., Cary, NC, USA), the POWER Procedure Wilcoxon-Mann-Whitney Test with the fixed scenario elements O'Brien-Castelloe approximation method and two-sided statistical evaluation. Power analysis sample data was derived from the previous open-label AAMs trial [Nummi 2021]. With a total sample size of 50 (two groups, group size 25, distribution 1:1) these parameters yield a power greater than 80% at an α of 0.05. Comparisons between groups will be performed with the Mann Whitney U test. Ordinal variables are tested with the Chi-Square test. Multiple comparisons are corrected with the Bonferroni method, significant findings are further tested groupwise using the Mann Whitney U test. Quality of life data is presented as means and analyzed with the independent samples t-test (two-sided). Analyses are performed with the IBM SPSS Statistics 27 program (IBM Corp., Armonk, NY) or equivalent. The data can be analyzed and published in phases during the trial. Data collection preoperatively and postoperatively during follow-up-Clinical, laboratory and drug treatment data are collected to the hospital electronic health records. After discharge and during follow-up patients can visit the primary healthcare. Any visit related to the operation or their cardiovascular system condition as well as drug treatment changes are collected by the study investigators. This data is stored pseudonymized with the other data from that patient. Data storage, management and sharing-The produced data are stored in the network hard drives of HUS and UH during analyses as well as on the servers of the CSC - IT CENTER FOR SCIENCE LTD. (Finland) specifically designed for sensitive data storage, all with automated backups. Directly identifying patient data with corresponding pseudonymization keys and randomization codes are stored in a key registry located within the safe hospital systems with automated backup and access control. The accession to the registries is controlled via role-based accession rights, and only those researchers specified in the registry description approved by the HUS Ethics Committee can access the data therein. PI-researcher docent Pasi Karjalainen is the responsible party for the key registry and its contents. The TTE data of participants is accessed via IntelliSpace software (Philips, Netherlands) that is ultimately stored on the Microsoft® Azure Cloud, which fulfills the HUS data security guidelines. The LGE-CMRI data and reports are stored to digital HUS picture archiving and communication system (PACS). When needed, the LGE-CMRI data are transferred internally between HUS Medical Imaging Center's servers to allow image analysis with appropriate CMR software. Case report formats are both physically stored in the HUS premises with an access control and electronically in the research registry. The accessions to the research registry are controlled via role-based accession rights and only those research team members singly specified in the registry description document, approved by the HUS Ethics Committee, can access the data therein. All workstations, network drives and servers are password protected. Prior any sharing of pseudonymized data with the academic study collaborators inside or outside European Union take place, whether performed via CSC - IT CENTER FOR SCIENCE LTD. (Finland) servers or with strong-password-protected hard drives transported by either official courier of the University of Helsinki or Helsinki University Hospital, the responsible collaborating scientist or the representative of the affiliated institution will sign Material Transfer Agreement (MTA). These MTAs will use the EU commission's Standard Contractual Clauses (SCCs) to protect the access, i.e. transfer, of the pseudonymized data. Also, all personnel handling pseudonymized data will be required to sign an official HUS secrecy and data security commitment. Moreover, the CSC - IT CENTER FOR SCIENCE LTD. requires its own data secrecy handling agreement for each collaborator to sign prior accessing the pseudonymized data. Principally, after the active phase of the trial, the produced data with pseudonyms will be stored on the servers of the Finnish IT Center for Science CSC (SD-Apply) for 15 years (2040). After this, the data is anonymized via erasing all the pseudonyms and curated indefinitely. A distinct Data Access Committee will monitor the re-use of the stored data. Also, the sequencing datasets with group-level anonymized metadata can be made available upon publication via uploading into repositories such as the European Nucleotide Archive (ENA) of the European Molecular Biology Laboratory European Bioinformatics Institute (EMBL-EBI, Cambridge, UK) or the Gene Expression Omnibus (GEO) functional genomics database repository (National Center for Biotechnology Information NCBI, Bethesda, MD, USA). Trial monitoring-The AAMS2 trial will be externally monitored by the Clinical Research Institute, Helsinki University Central Hospital (HUCH), or equivalent monitoring service provider, to ensure trial subjects' rights, safety, and well-being. A detailed monitoring plan will be drafted with the service provider and the research group before any patient is recruited to the study. Research team-The AAMS2 trial is conducted in collaboration with the HUS Heart and Lung Center (PI docent Pasi Karjalainen, and co-PI Antti Vento MD PhD) and University of Helsinki (docent Esko Kankuri MD PhD). The study nurse oversees and organizes, together with the PI, patient screening, recruitment, informing and contacting (via phone or mail), perioperative AAMs processing, and reservation of control visits. Moreover, the study nurse organizes study sample logistics in collaboration with scientists from University of Helsinki. Randomization is carried out at the University of Helsinki. The CABG surgery and application of AAMs patch is carried out by HUS Heart and Lung Center. LGE-CMRI imaging and analyses are carried by HUS Department of Radiology and University of Helsinki. The patient screening, recruitment, as well as both preoperative and postoperative clinical visits, which include TTE recordings, and clinical evaluation are conducted by the Cardiac Unit, HUS Heart and Lung Center. A heart-anesthesiologist will carry out recording of key postoperative parameters. Analysis of epitranscriptomic and other biomarkers is organized by the University of Helsinki, Faculty of Medicine, Department of Pharmacology.

Ischemic Heart Disease, Ischemic Cardiomyopathy, Heart Failure, Systolic, Heart Failure NYHA Class III, Heart Failure NYHA Class II, Heart Failure NYHA Class IV, Coronary Artery Disease

Ischemic heart failure, Ischemic heart disease, Coronary artery disease, Coronary artery bypass grafting, Atrial appendage micrografts, Tissue-engineering, Ischemic cardiomyopathy, Atrial appendage, Micrografts, Cell Therapy, Epitranscriptomics

The trial enrols 50 patients in a 1:1 group allocation ratio to the study groups (CABG [control group] or AAMs patch with CABG [intervention group]). Autologous RAA tissue is harvested from the RAA during CABG from all participants. Based on randomization, the piece of RAA tissue is either processed to AAMs perioperatively or stored for biochemical analyses. The AAMs, embedded in fibrin matrix gel, are placed on an ECM patch sheet, which is epicardially sutured in place. The epicardial transplantation site is pinpointed to ischemic scar area by preoperative LGE-CMRI.

Randomization is carried out by the University of Helsinki. Participants' running-numbered sealed envelopes with the randomized allocation information are handed out to the study nurse, who opens each respective envelope at the beginning of each patient's surgery. The study nurse oversees the allocation in a double-blinded manner, where the patient and the evaluating cardiologist and radiologists remain blinded to the study group allocation. Given the nature of the treatment (transplant vs. no transplant) it is impossible to blind the operating surgeon or the study nurse to the allocations.

In total, 25 patients are recruited to form the CABG group. During CABG surgery, RAA tissue is removed as detailed for the AAMs-patch group. However, the tissue is collected as a sample for later analyses rather than processed to AAMs (Method 4). CABG is performed without epicardial transplantation of AAMs-patch.

In total, 25 patients are recruited to the AAMs-patch group. Here, the AAMs are prepared from the RAA tissue sample by mechanical processing in the operating room during the CABG surgery. The RAA tissue piece is removed during right atrial cannulation, a part of the routine setup of cardiopulmonary bypass. To form an AAMs-patch, the AAMs, embedded in fibrin matrix gel, are placed onto an ECM sheet. This AAMs-patch is kept cold, covered, and sterile until the last stages of CABG surgery. After all the coronary anastomoses are done, the AAMs-patch is epicardially transplanted onto the area identified by preoperative LGE-CMRI to have most suffered from ischemia.

Collection (preoperative and at 6-month-follow-up) of TEMPUS(TM) stabilizing whole blood for epitranscriptomics-oriented measurements

Collection (preoperative and at 6-month follow-up) of blood-derived both RNA-stabilized and non-stabilized plasma aliquots for epitranscriptomic-oriented and other CVD biomarker oriented measurements, respectively

To assess cardiac structure and function both pre- and postoperatively (at both 3- and 6-month of follow-up)

To assess detailed cardiac structure (i.e. interstitial fibrosis) and function both preoperatively and at 6-month follow-up postoperatively.

Standardised evaluation of IHD and HF-related angina pectoris (CCS) and dyspnea (NYHA) and life quality (RAND36) pre- and postoperatively (at both 3- and 6-month follow-up).

Collection of a blood sample measurement of NT-proBNP by an accredited hospital laboratory pre- and postoperatively (at both 3- and 6-month follow-up).

Performed by the perfusion-anesthesiologist at the beginning of the CABG surgery to evaluate both LAA and RAA for blood flow velocities, anatomy, possible sludge and thrombus.

Measured by transthoracic echocardiography preoperatively and at the 3 and 6-months of follow-up Measured by LGE-CMRI preoperatively and at 6-months of follow-up

Feasibility: Success in completing the delivery of the AAMs patch onto the epicardium [ Time Frame: 6 months ]

Waiting time in minutes for the atrial appendage micrograft transplant to be placed on the myocardium (placement after completion of all the required anastomoses)

Waiting time in minutes for the heart after all the anastomoses are completed and before the AAMs patch is ready for epicardial transplantation.

Closing the right atrial appendage after removing the standardized tissue piece for preparing the transplant. According to the hospital protocol, appendage is closed with purse-string suture. 0 = no additional suturing needed, 1 = additional suturing needed

Transplant-related=1; Non-transplant-related=2; no infections=0 with details on organism, quantity, clinical and microbiological evaluation as well as harvesting site

Chronologic (preoperative vs. 6-month follow-up) and cross-sectional (AAMs patch vs. CABG group) correlation of blood epitranscriptomes, transcriptome, proteome and/or metabolome with the above outcomes.

Inclusion Criteria: Informed consent obtained Left ventricular ejection fraction (LVEF) between ≥ 15% and ≤ 40% at recruitment (transthoracic echocardiography) New York Heart Association (NYHA) Class II-IV heart failure symptoms Exclusion Criteria: Heart failure due to left ventricular outflow tract obstruction History of life-threatening and possibly repeating ventricular arrhythmias or resuscitation, or an implantable cardioverter-defibrillator Stroke or other disabling condition within 3 months before screening Severe valve disease or scheduled valve surgery Renal dysfunction (GFR <45 ml/min/1.73m2) Other disease limiting life expectancy Contraindications for coronary angiogram or LGE-CMRI Participation in some other clinical trial Screening Failure: After optimization of medications, no visible scar and LVEF ≥ 50% in preoperative LGE-CMRI Preoperative LGE-CMRI has not been performed prior scheduled CABG

Principally, after the active phase of the trial, the produced data with pseudonyms will be stored on the servers of the Finnish IT Center for Science CSC (SD-Apply) for 15 years (2040). After this, the data is anonymized via erasing all the pseudonyms and curated indefinitely. A distinct Data Access Committee will monitor the re-use of the stored data. Also, the sequencing datasets with group-level anonymized metadata can be made available upon publication via uploading into repositories such as the European Nucleotide Archive (ENA) of the European Molecular Biology Laboratory European Bioinformatics Institute (EMBL-EBI, Cambridge, UK) or the Gene Expression Omnibus (GEO) functional genomics database repository (National Center for Biotechnology Information NCBI, Bethesda, MD, USA).

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