Is left coronary system more susceptible to atherosclerosis than right? A pathophysiological insight.

On the basis of pathological, angiographical, intravascular ultrasound and computed tomography data coronary atherosclerosis appears to be more prevalent in the left coronary arterial system compared to the right. However, the pathophysiological mechanisms implicated in this discrepancy largely remain uncertain. The hemodynamic or anatomical differences between the right and left coronary artery might play a key role. Physiologically, the right coronary flow is more uniform during the cardiac cycle compared to the left, which experiences a remarkable systolic decline accompanied by a significant diastolic increment. Thus, the oscillatory shear stress, that constitutes a proved atherogenic factor, is more intense in regions with disturbed flow in the left coronary system. Likewise, the wall stress is more oscillatory during the cardiac cycle in the left coronary artery. On top of that, several differences regarding the anatomical configuration (3D geometry, branching) and the phasic motion between the right and the left arterial system appear to play a critical role in the modulation of the local atherogenic environment. Therefore, it could be assumed that the flow characteristics along with the geometrical and phasic motion patterns generate an intense oscillation of the imposed to the arterial wall stresses, especially in the left coronary artery. Over the long-term, these augmented oscillatory stresses, in combination with the effect of systemic risk factors, might modulate a more atherogenic environment in the atherosclerosis-prone regions of the left coronary system.