From the Guidelines
Type 2 myocardial infarction (MI) is defined as an ischemic MI in the context of a mismatch between oxygen supply and demand, unrelated to acute coronary atherothrombosis, and is characterized by the detection of a rise or fall of cardiac troponin concentrations with at least one value above the 99th percentile URL and evidence of an imbalance between myocardial oxygen supply and demand 1.
Key Characteristics of Type 2 MI
- The condition is caused by an imbalance between myocardial oxygen supply and demand, which can be due to various factors such as severe anemia, respiratory failure, hypotension, tachyarrhythmias, or coronary spasm.
- It is distinct from Type 1 MI, which is caused by atherothrombotic coronary artery disease and usually precipitated by atherosclerotic plaque disruption.
- Patients with Type 2 MI typically present with symptoms of acute myocardial ischemia, such as chest pain and shortness of breath, and have elevated cardiac biomarkers like troponin.
Diagnosis and Treatment
- The diagnosis of Type 2 MI requires the detection of a rise or fall of cardiac troponin concentrations with at least one value above the 99th percentile URL, along with evidence of an imbalance between myocardial oxygen supply and demand 1.
- Treatment focuses on addressing the underlying cause of the oxygen supply-demand mismatch, rather than immediate coronary intervention.
- This may include blood transfusions for anemia, oxygen therapy for respiratory issues, or medications to stabilize blood pressure or heart rate.
Importance of Recognition
- Recognizing Type 2 MI is crucial because the management approach differs significantly from the standard coronary intervention used for Type 1 MI.
- Careful identification and treatment of the specific oxygen supply-demand mismatch causing the cardiac injury are necessary to improve patient outcomes.
- The prognosis for Type 2 MI depends largely on successfully treating the underlying conditions, highlighting the need for prompt and accurate diagnosis and treatment 1.
From the Research
Definition of Type 2 Myocardial Infarction (MI)
- Type 2 MI occurs due to a mismatch in myocardial oxygen supply and demand without unstable coronary artery disease 2, 3, 4.
- It is characterized by an imbalance between myocardial blood supply and demand, leading to myocardial ischemia without coronary plaque rupture 5.
- Type 2 MI is defined by a rise and fall of cardiac biomarkers and evidence of ischemia without unstable coronary artery disease (CAD) because of a mismatch in myocardial oxygen supply and demand 3.
Causes and Provoking Factors
- The most frequent potential provoking factors for type 2 MIs include tachyarrhythmias, anemia/bleeding, hypotension/shock, and hypertensive emergencies 5.
- Conditions associated with type 2 MI or myonecrosis include non-cardiac surgery, anemia or bleeding requiring transfusion, sepsis, tachyarrhythmia, hypotension, respiratory failure, and severe hypertension 6.
Management and Outcomes
- Invasive management of type 2 MI varies by insurance status and geography, highlighting uncertainty regarding optimal management and potential disparities in clinical care 2.
- Patients with type 2 MI were less likely to receive aspirin and statin at discharge than type 1 MI survivors 3.
- All-cause mortality was not different between patient groups (type 1 MI, type 2 MI, and myocardial injury) 3.
- Inpatient mortality was 5%, with no difference between patients with MI and those with myonecrosis 6.