From the Guidelines
Type 2 myocardial infarction (MI) is characterized by an imbalance between myocardial oxygen supply and demand, not caused by coronary plaque instability, but rather by conditions such as hypotension, hypertension, tachyarrhythmias, bradyarrhythmias, anemia, hypoxemia, coronary artery spasm, spontaneous coronary artery dissection (SCAD), coronary embolism, and coronary microvascular dysfunction, as defined in the 2020 ESC guidelines for the management of acute coronary syndromes 1.
Key Characteristics of Type 2 MI
- Imbalance between oxygen supply and demand in the heart
- Not caused by coronary artery blockage
- Secondary to conditions like severe anemia, respiratory failure, hypotension, or tachyarrhythmias
- Treatment focuses on addressing the underlying cause rather than immediate coronary intervention
Management of Type 2 MI
- Oxygen therapy if needed
- Blood pressure support with fluids or vasopressors in hypotension
- Blood transfusions for severe anemia
- Heart rate control for tachyarrhythmias
- Medications may include beta-blockers, antiplatelet agents like low-dose aspirin, and statins for their pleiotropic effects
Long-term Management
- Optimizing treatment of chronic conditions like hypertension or diabetes that may have contributed to the oxygen imbalance
- Unlike type 1 MI, anticoagulants and emergency catheterization are not routinely indicated unless there's evidence of concurrent coronary disease, as noted in the 2022 ACC/AHA key data elements and definitions for chest pain and acute myocardial infarction 1.
From the Research
Definition and Characteristics of Type 2 Myocardial Infarction
- Type 2 myocardial infarction (MI) is defined as an elevation of cardiac biomarkers in a physiologically stressful state leading to demand-supply mismatch of oxygen 2.
- It is characterized by a rise and fall of cardiac biomarkers and evidence of ischemia without unstable coronary artery disease (CAD) due to a mismatch in myocardial oxygen supply and demand 3.
- Type 2 MI is highly prevalent and strongly associated with mortality, but the pathophysiology remains poorly understood 4.
Diagnosis and Management
- There is no consensus on the diagnostic criteria for type 2 MI, and discrepancies in definitions, frequency of screening, diagnostic approaches, and methods of adjudication lead to confusion and misclassification 4.
- No guidelines exist for the optimal management of type 2 MI, and further investigation is urgently needed 4.
- Patients with type 2 MI require individualized care, and limited data exist defining optimal management strategies due to the heterogeneous entity with varying etiologies and triggers 5.
Prognosis and Outcomes
- Type 2 MI is associated with adverse short-term and long-term prognoses 5.
- All-cause mortality was not different between type 1 MI, type 2 MI, and myocardial injury patients, but a significant proportion of deaths were attributed to cardiovascular causes in all subgroups 3.
- Patients with type 2 MI were less likely to receive aspirin and statin at discharge, and medical therapy for CAD than those with type 1 MI 3.
Treatment Strategies
- Secondary prevention therapies may play a role in decreasing adverse events from type 2 MI 2.
- Beta-blockers and calcium channel blockers can reduce myocardial oxygen demand and improve oxygen supply, and are effective in the treatment of chronic stable angina, vasospastic angina, and unstable angina 6.