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  • Myocardial ischemia results from an imbalance between myocardial oxygen demand and supply.

  • Myocardial infarction is diagnosed by a compatible clinical history, evolution of characteristic ECG changes, and a rise and fall of cardiac troponins.

  • Patients with myocardial ischemia are divided by presentation into those with or without ST elevation, in accordance with treatment strategies. Patients with ST elevation benefit from immediate reperfusion with percutaneous coronary intervention.

  • Risk stratification is the key to initial management of patients with non-ST-elevation acute coronary syndromes. An early invasive approach is preferred in patients with high-risk non-ST-elevation acute coronary syndromes.

  • All patients with suspected myocardial ischemia should be given aspirin upon presentation.

  • Aspirin, P2Y12 inhibitors, β-blockers, renin-angiotensin-aldosterone system antagonists, and statins have been shown to decrease mortality after myocardial infarction.

  • Prognosis after myocardial infarction is most closely related to the degree of left ventricular impairment.

  • Echocardiography is extremely useful for the diagnosis of complications after myocardial infarction.

  • Patients with cardiogenic shock should be stabilized with prompt revascularization and may require inotropes or mechanical circulatory support. Invasive hemodynamic monitoring should be strongly considered.


Myocardial ischemia can go unrecognized in an intensive care unit (ICU) setting. Signs and symptoms of myocardial ischemia can be obscured by other illnesses in the critically ill patient. Obtaining an accurate clinical history can be challenging in patients with altered sensorium and physical examination is often limited by the presence of comorbid illnesses.

Myocardial ischemia and left ventricular (LV) dysfunction may complicate the course and treatment of the primary noncardiac illness. Conversely, multisystem illness may increase myocardial oxygen demand, which can result in myocardial ischemia even in the absence of acute coronary plaque rupture. For these reasons, the critical care physician must maintain a high index of suspicion for myocardial ischemia in the ICU setting, especially in the patient with multiple risk factors for coronary artery disease.


Myocardial ischemia secondary to coronary artery disease has traditionally been divided into categories including stable angina, unstable angina (UA), and myocardial infarction (MI). Typical angina is described as substernal chest pain which is exertional and relieved promptly by rest or nitroglycerin.1 Stable angina occurs reproducibly with a similar level of exertion, in a pattern unchanged over the past 6 months. UA consists of ischemic symptoms which are more severe than the patient’s usual angina, difficult to control with drugs, and occur at rest or with minimal exertion. Cardiac biomarkers are not elevated.

Although acute coronary syndromes (ACS) were previously classified by the presence or absence of Q-waves in the electrocardiogram (ECG), more recent classification is based on ST-segment changes. Patients are divided into two groups: those with ST elevation (STEMI), and those without ST elevation (non-ST-elevation ACS or NSTE-ACS). NSTE-ACS encompasses both the diagnosis of UA and non-ST-elevation myocardial infarction (NSTEMI). The distinction between NSTEMI and UA ...

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