Coronary ischemia

Coronary ischemia, myocardial ischemia, or cardiac ischemia, is a medical term for abnormally reduced blood flow in the coronary circulation through the coronary arteries. Coronary ischemia is linked to heart disease, and heart attacks. Coronary arteries deliver oxygen-rich blood to the heart muscle. Reduced blood flow to the heart associated with coronary ischemia can result in inadequate oxygen supply to the heart muscle. When oxygen supply to the heart is unable to keep up with oxygen demand from the muscle, the result is the characteristic symptoms of coronary ischemia, the most common of which is chest pain. Chest pain due to coronary ischemia commonly radiates to the arm or neck. Certain individuals such as women, diabetics, and the elderly may present with more varied symptoms. If blood flow through the coronary arteries is stopped completely, cardiac muscle cells may die, known as a myocardial infarction, or heart attack.

Coronary artery disease (CAD) is the most common cause of coronary ischemia. Coronary ischemia and coronary artery disease are contributors to the development of heart failure over time. Diagnosis of coronary ischemia is achieved by an attaining a medical history and physical examination in addition to other tests such as electrocardiography (ECG), stress testing, and coronary angiography. Treatment is aimed toward preventing future adverse events and relieving symptoms. Beneficial lifestyle modifications include smoking cessation, a heart healthy diet, and regular exercise. Medications such as nitrates and beta-blockers may be useful for reducing the symptoms of coronary ischemia, with beta-blockers also improving long term outcomes in most studies. In refractory cases, invasive procedures such as percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) may be performed to relieve coronary ischemia.

Recently, evidence has been found that ischemia can also occur without coronary obstruction (a conditional known as INOCA - ischemia with no obstructed arteries). Other studies have found that long COVID or post acute COVID syndrome can also be associated with myocardial ischemia. Treatment for both conditions is similar to treatment for ischemia caused by CAD.

INOCA is cardiac ischemia with no coronary artery obstruction. Approximately 3-4 million people have been diagnosed with this condition; with female diagnosis prevalent. Risk factors include female sex, advanced age, smoking, hyperlipidemia, inflammatory disease, diabetes and glucose intolerance. Diagnosis of INOCA can begin with non-invasive testing including PET with myocardial perfusion imaging (MPI) or stress cardiovascular magnetic resonance (CMR) imaging. However, final diagnosis must be made with cardiac angiography to confirm the absence of occlusion.

Data involving cardiac ischemia resulting from post acute COVID syndrome (or Long COVID) is evolving. Various studies have been combined to show a significant percentage of patients presenting with myocardial ischemia post COVID infection (infection requiring hospitalization) with no documented prior history of coronary disease. Vaccination (with 2 doses) has been shown to decrease the risk of Long COVID in recent studies.

A key symptom of coronary ischemia is chest pain or pressure, known as angina pectoris. Angina may present typically with classic symptoms or atypically with symptoms less often associated with heart disease. Atypical presentations are more common in women, diabetics, and elderly individuals. Angina may be stable or unstable. Unstable angina is most often associated with emergent, acute coronary syndromes.

Angina is typically located below the sternum. Individuals experiencing angina characterize the pain in different ways, but the pain is usually described as crushing, squeezing, or burning. Symptoms may worsen over the course of several minutes. Typical angina is aggravated by physical activity or emotional stress and is relieved by rest or nitroglycerin. The pain may radiate to other parts of the body, most commonly the left arm or neck. In some individuals, the pain may be less severe and present as pressure or numbness. Less commonly, the pain may radiate to both arms, the jaw, or to the back.

Women, diabetic individuals, and elderly individuals are more likely to present with atypical symptoms other than chest pain. Women may present with back pain, shortness of breath, heartburn, nausea, and vomiting. Heart disease in women goes undetected prior to a major cardiac event in up to 60% of cases. Among women who experience a heart attack, many do not have any prior chest pain. Due to alterations in sensory pathways, diabetic and elderly individuals also may present without any chest pain and may have atypical symptoms similar to those seen in women. This type of ischemia is also known as silent ischemia.