Observational cohort study.

Current guidelines recommend myocardial revascularization in patients with moderate to severe symptoms persisting after adequate medical therapy, or for whom the outcome could be improved. Conventional coronary artery bypass grafting (CABG), off-pump coronary artery bypass (OPCAB), minimally invasive direct coronary artery bypass (MIDCAB), and off-pump coronary artery bypass surgery through a J-shaped hemisternotomy (JOPCAB) are possible surgical revascularization procedures, while PCI with or without bare-metal or drug-eluting stenting are alternatives to the surgical procedures. Furthermore, a third approach has been introduced as an alternative treatment of multivessel coronary artery disease, that is the hybrid myocardial revascularization, combining revascularization of the proximal LAD to the internal mammary artery preferably with minimal invasive techniques with PCI to non-LAD lesions. CABG has been found to provide mid-term survival benefit and a lower risk of repeat revascularization compared to PCI in patients with complex coronary artery disease. Current knowledge regarding optimal treatment of less complex disease is limited. Evidence regarding the impact of varying de-grees of guideline adherence on clinical outcome is scarce.

Large, well-powered studies with a significant follow-up time examining the long-term outcome of surgical revascularization procedures, PCI, and HMR are warranted. We aim to investigate current myocardial revascularization practices and compare long-term outcome of different surgical revascularisation strategies, PCI, and HMR in patients with chronic coronary syndromes, treated in Denmark or Sweden between 2000 and 2020. Adult, elective patients who underwent first time isolated CABG, PCI, or HMR will be identified through large, nationwide registries.

The purpose of the study is to investigate current myocardial revascularization practices and compare long-term outcome of different surgical revascularisation strategies, percutaneous coronary intervention (PCI), and hybrid myocardial revascularization (HMR) in patients with chronic coronary syndromes. The study will be based on the following three sub-aims:

• To compare the long-term outcome after isolated surgical revascularization to PCI in patients with chronic isolated left anterior descending (LAD) artery disease.
• To compare the long-term outcome after myocardial revascularization in patients with chronic multivessel coronary artery disease involving the proximal LAD in relation to guideline adherence in Danish and Swedish centres.
• To compare the long-term outcome after HMR to multivessel PCI in patients with chronic multivessel coronary artery disease.

The study is conducted in collaboration between Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark and Department of Cardiothoracic Surgery, Sahlgrenska University Hospital, Gothenburg, Sweden.

• Alexander Emil Kaspersen, MD
  Department of Cardiothoracic and Vascular Surgery and Department of Clinical Medicine, Aarhus University Hospital and Aarhus University, Denmark
• Susanne Nielsen, RN, PhD, Associate Professor
  Department of Cardiothoracic Surgery and Department of Molecular and Clinical Medicine, Sahlgrenska University Hospital and Gothenburg University, Gothenburg, Sweden
• Per Hostrup Nielsen, MD, Consultant
  Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Denmark
• Michael Mæng, MD, PhD, Clinical Associate Professor, Consultant
  Department of Cardiology and Department of Clinical Medicine, Aarhus University Hospital and Aarhus University, Aarhus, Denmark
• Anders Jeppsson, MD, PhD, Clinical Professor, Consultant
  Department of Cardiothoracic Surgery and Department of Molecular and Clinical Medicine, Sahlgrenska University Hospital and Gothenburg University, Gothenburg, Sweden
• Ivy Susanne Modrau, MD, dr.med., Clinical Associate Professor, Consultant
  Department of Cardiothoracic and Vascular Surgery and Department of Clinical Medicine, Aarhus University Hospital and Aarhus University, Denmark

Inge og Asker Larsens Fond, Jens Anker Andersen Fonden, A.P. Møller Fonden, Ketty og Ejvind Lyngsbæks Fond, and Familien Hede Nielsens Fond.