Do the coronary arteries perfuse the myocardium?

From the Guidelines

Yes, the coronary arteries do perfuse the myocardium. The coronary arteries are the blood vessels responsible for delivering oxygen-rich blood to the heart muscle (myocardium) [ 1 ]. The two main coronary arteries are the left coronary artery and the right coronary artery, which branch off from the aorta just above the aortic valve. The left coronary artery further divides into the left anterior descending artery and the circumflex artery. These vessels and their smaller branches form a network that supplies blood to all regions of the heart muscle. This perfusion is critical because the myocardium has high energy demands due to its continuous contractile activity. Without adequate coronary perfusion, the heart muscle would quickly become ischemic, potentially leading to myocardial infarction (heart attack) and tissue death.

Key Points

• The coronary circulation is unique because blood flow occurs primarily during diastole (when the heart relaxes) rather than systole (when the heart contracts), as the vessels are compressed during contraction [ 1 ].
• Coronary blood flow provides the needed oxygen supply for any given myocardial oxygen demand and normally increases automatically from a resting level to a maximum level in response to increases in myocardial oxygen demand from exercise and neurohumoral or pharmacological hyperemic stimuli [ 1 ].
• Atherosclerotic narrowings produce epicardial vessel resistance and, after a critical reduction in vessel lumen area, can abolish not only coronary reserve but also autoregulation, thus reducing resting coronary blood flow [ 1 ].
• Stress SPECT MPI can identify relative myocardial perfusion defects, indicating the presence of myocardial ischemia and/or infarction [ 1 ].
• Management targeted at optimizing the determinants of coronary arterial perfusion is recommended to reduce the risk of perioperative myocardial ischemia and infarction [ 1 ].

Clinical Implications

• The coronary arteries play a crucial role in maintaining the health and function of the myocardium.
• Any reduction in coronary perfusion can lead to serious consequences, including myocardial infarction and death.
• Therefore, it is essential to prioritize the management of coronary artery disease and optimize coronary arterial perfusion to reduce the risk of adverse outcomes [ 1 ].

From the Research

Coronary Arteries and Myocardium Perfusion

• The coronary arteries play a crucial role in perfusing the myocardium, and their disease is a primary risk factor for heart failure development 2, 3.
• Coronary artery disease (CAD) is recognized as the main etiological factor in more than 50% of heart failure patients in North America and Europe 3.
• Myocardial ischemia is a common finding in failing hearts, likely due to structural or functional coronary circulation alterations, and is a self-propagating process that irreversibly impairs cardiac function and negatively impacts prognosis 3, 4.
• The pathophysiological mechanisms underlying the link between hypertension and CAD are complex and include overactivation of neurohormones, accelerated development of the atherosclerotic plaque, endothelial dysfunction, altered intramyocardial coronary circulation, hypertension-mediated cardiac and vascular damage, and the relationship between arterial stiffness and coronary perfusion 5, 6.

Importance of Coronary Perfusion

• Perfusion of the left ventricle occurs predominantly during diastole, and coronary autoregulation may be exhausted with low diastolic blood pressure in the setting of left ventricular hypertrophy and atherosclerotic narrowing of the epicardial coronaries 5.
• Blood pressure reduction is associated with a significant decrease in the risk of coronary events, and therapeutic interventions targeted to reduce blood pressure and improve endothelial function and coronary microvascular dysfunction contribute to reducing the burden of coronary disease and its acute ischemic manifestations 5, 6.
• The primary blood pressure goal in patients with established CAD is below 140/90 mmHg, and recent studies suggest that a lower systolic blood pressure may be appropriate, whereas caution is advised with diastolic blood pressure below 60 mmHg 5.