From the Guidelines
Cardiogenic shock following myocardial infarction (MI) requires immediate intervention with a multifaceted approach, prioritizing hemodynamic stabilization and urgent coronary revascularization, as supported by the most recent guidelines and evidence 1.
Initial Management
Initial management includes hemodynamic stabilization with intravenous fluids if the patient is hypovolemic, but careful monitoring is essential as excessive fluid can worsen heart failure.
- Vasopressors and inotropes are typically needed, with norepinephrine (starting at 0.1-0.5 mcg/kg/min) as the first-line vasopressor and dobutamine (2.5-20 mcg/kg/min) as the preferred inotrope for improving cardiac output.
- Mechanical circulatory support should be considered early, with intra-aortic balloon pump or Impella devices providing temporary support while arranging for urgent coronary revascularization.
Coronary Revascularization
Primary percutaneous coronary intervention (PCI) should be performed as soon as possible, ideally within 90 minutes of first medical contact, as recommended by the 2011 ACCF/AHA/SCAI guideline for percutaneous coronary intervention 1.
- Adjunctive pharmacotherapy includes dual antiplatelet therapy (aspirin 325 mg loading dose followed by 81 mg daily, plus a P2Y12 inhibitor like ticagrelor 180 mg loading dose followed by 90 mg twice daily), anticoagulation with unfractionated heparin, and high-intensity statin therapy.
Ongoing Care
Continuous monitoring in an intensive care setting with frequent assessment of vital signs, urine output, and laboratory parameters is crucial.
- The underlying pathophysiology involves a vicious cycle where myocardial damage reduces cardiac output, leading to hypoperfusion, which further compromises myocardial function and can progress to multi-organ failure if not promptly addressed.
- Recent studies, such as the one published in Circulation in 2021 1, highlight the importance of early mechanical circulatory support in patients with cardiogenic shock after MI, although the choice of device and timing of insertion may influence outcomes.
From the FDA Drug Label
In some of the reported cases of vascular collapse due to acute myocardial infarction, treatment was required for up to six days. The answer to shock following MI is that norepinephrine (IV) can be used to restore and maintain adequate blood pressure, and treatment may be required for up to six days 2.
- Key points:
- Norepinephrine (IV) is used to restore and maintain adequate blood pressure
- Treatment may be required for up to six days
- The dosage should be titrated according to the response of the patient
- Central venous pressure monitoring is usually helpful in detecting and treating occult blood volume depletion.
From the Research
Definition and Prevalence of Cardiogenic Shock
- Cardiogenic shock is a serious complication of myocardial infarction (MI) that affects approximately 7% of MI patients, accounting for the majority of all deaths related to acute infarction 3.
- It is estimated that cardiogenic shock affects between 40 000 and 50 000 people in the US per year and is the leading cause of in-hospital mortality following acute myocardial infarction 4.
- Cardiogenic shock occurs in up to 10% of patients immediately following acute myocardial infarction and is associated with mortality rates of nearly 40% at 30 days and 50% at 1 year 4.
Treatment and Management
- Immediate revascularization of the infarct-related coronary artery remains the only treatment for cardiogenic shock associated with acute myocardial infarction supported by randomized clinical trials 4.
- The Percutaneous Coronary Intervention Strategies with Acute Myocardial Infarction and Cardiogenic Shock (CULPRIT-SHOCK) clinical trial demonstrated a reduction in the primary outcome of 30-day death or kidney replacement therapy 4.
- Early percutaneous coronary intervention and coronary artery bypass grafting are causal therapies implemented in cardiogenic shock, supported by catecholamines, fluids, intra-aortic balloon pumping, and also active percutaneous assist devices 5.
- A multitarget approach to cardiogenic shock following acute myocardial infarction is proposed, including myocardial revascularization strategies and the use of mechanical circulatory support 6.
Outcomes and Prognosis
- Thirty-day mortality for patients with cardiogenic shock due to myocardial infarction is approximately 40%, and 1-year mortality approaches 50% 4.
- Acute myocardial infarction was associated with increased rates of adverse clinical outcomes in cardiogenic shock, along with increased rates of mortality and initiation of mechanical circulatory support and renal replacement therapy 7.
- The primary composite end point, including all-cause in-hospital mortality, cardiac arrest, non-fatal myocardial infarction, cerebrovascular accident, the need for mechanical circulatory support, or initiation of renal replacement therapy at 30-days, was significantly higher in patients with acute myocardial infarction complicated by cardiogenic shock versus non-acute myocardial infarction cardiogenic shock 7.