From the Guidelines
Type 2 myocardial infarction (MI) should be managed by treating the underlying cause of the imbalance between myocardial oxygen supply and demand, rather than pursuing immediate coronary intervention, as stated in the 2020 ESC guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation 1. The diagnosis of Type 2 MI is based on the detection of a rise and/or fall of cardiac biomarkers, such as troponin, with at least one value above the 99th percentile upper reference limit, and evidence of an imbalance between myocardial oxygen supply and demand, such as hypotension, hypertension, tachyarrhythmias, bradyarrhythmias, anemia, hypoxaemia, coronary artery spasm, or coronary microvascular dysfunction 1. Key aspects of management include:
- Oxygen therapy if saturation is below 90%
- Pain control with medications like morphine
- Addressing the primary condition causing oxygen supply-demand mismatch
- Diagnostic workup involving cardiac biomarkers, ECG, and assessment for the underlying etiology
- Risk factor modification, including blood pressure and diabetes control, smoking cessation, and cholesterol management
- Medications such as aspirin (81mg daily), statins, beta-blockers, and ACE inhibitors if appropriate Unlike Type 1 MI, antiplatelet therapy may be less emphasized and coronary angiography is not routinely performed unless the underlying cause remains unclear 1. Long-term follow-up should focus on managing the condition that precipitated the Type 2 MI to prevent recurrence, as emphasized in the 2017 AHA/ACC clinical performance and quality measures for adults with ST-elevation and non-ST-elevation myocardial infarction 1.
From the FDA Drug Label
Myocardial Infarction Metoprolol tartrate injection is indicated in the treatment of hemodynamically stable patients with definite or suspected acute myocardial infarction to reduce cardiovascular mortality. Early Treatment During the early phase of definite or suspected acute myocardial infarction, initiate treatment with metoprolol tartrate as soon as possible after the patient’s arrival in the hospital.
The diagnosis of Type 2 Myocardial Infarction (MI) is not directly addressed in the provided drug labels. The treatment for Myocardial Infarction (MI) with metoprolol tartrate injection is indicated for hemodynamically stable patients to reduce cardiovascular mortality, and treatment can be initiated as soon as the patient's clinical condition allows 2. The dosage and administration for myocardial infarction include intravenous administration of three bolus injections of 5 mg of metoprolol tartrate injection each, followed by metoprolol tartrate tablets 50 mg every 6 hours 2. Key points for treatment include:
- Initiate treatment as soon as possible after the patient's arrival in the hospital
- Monitor blood pressure, heart rate, and electrocardiogram during intravenous administration
- Start metoprolol tartrate tablets 15 minutes after the last intravenous dose
- Maintenance dosage is 100 mg orally twice daily 2
From the Research
Diagnosis of Type 2 Myocardial Infarction (MI)
- Type 2 MI is characterized by a functional imbalance between myocardial oxygen supply and demand in the absence of a thrombotic process, leading to myocardial necrosis 3
- The diagnosis of Type 2 MI is based on the elevation of cardiac biomarkers in a physiologically stressful state leading to demand-supply mismatch of oxygen 4
- The diagnosis can be confirmed by the presence of myocardial oxygen supply-demand imbalance, which may be caused by various factors such as tachyarrhythmia, hypoxemia, anemia, hypotension, severe hypertension, and coronary mechanisms 5
Treatment of Type 2 Myocardial Infarction (MI)
- The treatment of Type 2 MI remains essentially based on the restoration of the balance between oxygen supply and demand 3
- The management of Type 2 MI requires a comprehensive approach that is tailored to each case, taking into account the underlying etiological factors 3
- Treatment may include medications such as aspirin, nitroglycerin, and antihypertensive drugs, as well as lifestyle modifications such as controlling diet, fat, cholesterol, salt, smoking, nicotine, alcohol, and drugs, and monitoring of blood pressure and exercise 6
- Cardiac rehabilitation (CR) may also be beneficial for patients with Type 2 MI, although specific recommendations for CR are lacking 7
Factors Associated with Oxygen Supply-Demand Imbalance
- The most common factor associated with oxygen supply-demand imbalance in Type 2 MI is tachyarrhythmia, followed by hypoxemia, anemia, hypotension, severe hypertension, and coronary mechanisms 5
- The underlying etiologic factor associated with oxygen supply-demand imbalance can affect the prognosis of patients with Type 2 MI, with hypoxemia and anemia being associated with a higher risk of death 5