First classification of four stages of heart attack based on heart muscle damage Is released

Heart attacks, or acute myocardial infarction (MI), are one of the leading causes of death worldwide. The newly released Canadian Cardiovascular Society Classification of Acute Myocardial Infarction opens in new tab/window (CCS-AMI) appearing in the Canadian Journal of Cardiology opens in new tab/window, published by Elsevier, presents a four-stage classification of heart attack based on heart muscle damage. This work by a group of noted experts has the potential to stratify risk more accurately in heart attack patients and lays the groundwork for development of new, injury-stage-specific and tissue pathology-based therapies.

Lead author Andreas Kumar, MD, MSc, Northern Ontario School of Medicine University, and Department of Cardiovascular Sciences, Health Sciences North, Sudbury, ON, Canada, explains: “MI remains a leading cause of morbidity and mortality. Existing tools classify MIs using a patient’s clinical presentation and/or the cause of the heart attack, as well as ECG findings. Although these tools are very helpful to guide treatment, they do not consider details of the underlying tissue damage caused by the heart attack. This expert consensus, based on decades of data, is the first classification system of its kind ever released in Canada and internationally. It offers a more differentiated definition of heart attacks and improves our understanding of acute atherothrombotic MI. On a tissue level, not all heart attacks are the same; the new CCS-AMI classification paves the way for development of more refined therapies for MI, which could ultimately result in better patient clinical care and improved survival rates.”

The CCS-AMI classification describes damage to the heart muscle following an MI in four sequential and progressively severe stages. Each stage reflects progression of tissue pathology of myocardial ischemia and reperfusion injury from the previous stage. It is based on a strong body of evidence about the effect an MI has on the heart muscle.

As damage to the heart increases through each progressive CCS-AMI stage, patients have dramatically increased risk of complications such as arrhythmia, heart failure, and death. Appropriate therapy can potentially stop injury from progressing and halt the damage at an earlier stage.

• Stage 1: Aborted MI (no/minimal myocardial necrosis). No or minimal damage to the heart muscle. In the best case the entire area of myocardium at risk may be salvaged.

• Stage 2: MI with significant cardiomyocyte necrosis, but without microvascular injury. Damage to the heart muscle and no injury to small blood vessels in the heart. Revascularization therapy will result in restoration of normal coronary flow.

• Stage 3: MI with cardiomyocyte necrosis and microvascular dysfunction leading to microvascular obstruction (i.e., “no-reflow”). Damage to the heart muscle and blockage of small blood vessels in the heart. The major adverse cardiac event rate is increased 2- to 4-fold at long-term follow-up.

• Stage 4: MI with cardiomyocyte and microvascular necrosis leading to reperfusion hemorrhage. Damage to the heart muscle, blockage and rupture of small blood vessels resulting in bleeding into the heart muscle. This is a more severe form of microvascular injury, and the most severe form of ischemia-reperfusion injury. It is associated with a further increase in adverse cardiac event rate of 2- to 6-fold at long-term follow-up.

Dr. Kumar concludes: The new classification will help differentiate heart attacks according to the stage of tissue damage and allow healthcare providers to estimate a patient’s risk more precisely for arrhythmia, heart failure, and death.The CCS-AMI is ultimately expected to lead to better care, better recovery, and better survival rates for heart attack patients.”

In an accompanying editorial opens in new tab/window, Prakriti Gaba, MD, Brigham and Women’s Hospital, Harvard Medical School, and Deepak L. Bhatt, MD, MPH, Mount Sinai Heart, Icahn School of Medicine at Mount Sinai, comment: “Kumar et al. present a novel and intriguing four-tiered classification scheme of patients with acute MI. This allows unique utilization of prognostic pathologic features to help distinguish between high and low risk acute MI patients. Greater access to cardiovascular magnetic resonance would be needed to implement this new clinical approach broadly, however, for research on emerging diagnostic and therapeutic strategies, it could be implemented immediately.”

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Notes for editors

The article is “The Canadian Cardiovascular Society Classification of Acute Atherothrombotic Myocardial Infarction Based on Stages of Tissue Injury: An Expert Consensus Statement,” by Andreas Kumar, MD, MSc (Chairperson of the Writing Group, corresponding author), Kim Connelly, MD, PhD, Keyur Vora, MD, MS, Kevin R. Bainey, MD, MSc, Andrew Howarth, MD, PhD, Jonathon Leipsic, MD, Suzanne Betteridge-LeBlanc, BSc, RN, Frank S. Prato, PhD, Howard Leong-Poi, MD, Anthony Main, MD, Rony Atoui, MD, MSc, Jacqueline Saw, MD, Eric Larose, MD, PhD, Michelle M. Graham, MD, Marc Ruel, MD, MPH, and Rohan Dharmakumar, PhD. (https://doi.org/10.1016/j.cjca.2023.09.020 opens in new tab/window). It is openly available at https://www.onlinecjc.ca/article/S0828-282X(23)01735-X opens in new tab/window.

The editorial is “Promise of a Novel Classification System for Acute Myocardial Infarction,” by Prakriti Gaba, MD, and Deepak L. Bhatt, MD, MPH (https://doi.org/10.1016/j.cjca.2023.10.011 opens in new tab/window). It is openly available at https://www.onlinecjc.ca/article/S0828-282X(23)01839-1 opens in new tab/window.

The articles appear online in the Canadian Journal of Cardiology, published by Elsevier.

Full text of the articles is also available to credentialed journalists upon request. Contact Eileen Leahy at +1 732 238 3628or [email protected] opens in new tab/window to obtain copies. Journalists wishing to speak to the study’s authors should contact Stephanie Naday, Director of Communications/Directrice, Communications, Canadian Cardiovascular Society/Société cardiovasculaire du Canada, at +1 403 828 1017 or [email protected] opens in new tab/window. To reach the editorial’s authors for comment contact Deepak L. Bhatt, MD, MPH, at +1 212 241 5174 or [email protected] opens in new tab/window.

The CCS-AMI is an expert consensus statement. Andreas Kumar, MD, MSc (Cardiologist, Associate Professor of Medicine, NOSM University, Canada) and Rohan Dharmakumar, PhD (Executive Director and Charles Fish Professor of Cardiology, Krannert Cardiovascular Research Center of Indiana University, USA) initially developed the classification. Then, the Canadian Cardiovascular Society (CCS) formed an expert writing group to review and refine it. CCS has also established a working group to allow for ongoing clinical and scientific refinement of the CCS-AMI.

About the Canadian Journal of Cardiology

The Canadian Journal of Cardiology opens in new tab/window is the official journal of the Canadian Cardiovascular Society opens in new tab/window. It is a vehicle for the international dissemination of new knowledge in cardiology and cardiovascular science, particularly serving as a major venue for the results of Canadian cardiovascular research and Society guidelines. The journal publishes original reports of clinical and basic research relevant to cardiovascular medicine as well as editorials, review articles, case reports, and papers on health outcomes, policy research, ethics, medical history, and political issues affecting practice. www.onlinecjc.ca opens in new tab/window

About the Editor-in-Chief

Editor-in-Chief Stanley Nattel, MD, is Paul-David Chair in Cardiovascular Electrophysiology and Professor of Medicine at the University of Montreal and Director of the Electrophysiology Research Program at the Montreal Heart Institute Research Center.

About the Canadian Cardiovascular Society (CCS)

The CCS opens in new tab/window is the national voice for cardiovascular clinicians and scientists, representing more than 2,300 cardiologists, cardiac surgeons and other heart health specialists across Canada. We advance heart health for all by setting standards for excellence in heart health and care, building the knowledge and expertise of the heart team, and influencing policy and advocating for the heart health of all Canadians. For further information on the CCS visit https://www.ccs.ca/en opens in new tab/window.

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