Left Main Disease and Coronary Dominance
The available evidence does not support that left main coronary artery disease is more common in left dominant circulation. The relationship between coronary dominance and left main disease prevalence has not been established in the medical literature, though left dominance may be associated with worse outcomes when left main disease is present.
Prevalence of Left Main Disease
Left main coronary artery disease occurs in approximately 4% of all patients undergoing coronary angiography, regardless of coronary dominance pattern 1, 2. This prevalence rate is consistent across studies and does not vary based on whether the patient has right, left, or codominant circulation 2.
Impact of Coronary Dominance on Outcomes
While left dominance does not increase the prevalence of left main disease, it does appear to affect outcomes when acute coronary syndromes occur:
Left or codominant circulation is associated with higher in-hospital mortality following PCI for acute coronary syndromes compared to right dominant circulation 3.
In a large registry of 207,926 PCI procedures for acute coronary syndromes, left dominance was associated with 29% higher unadjusted mortality (OR 1.29,95% CI 1.17-1.42) and 19% higher adjusted mortality (OR 1.19,95% CI 1.06-1.34) compared to right dominance 3.
Codominance showed increased mortality only in adjusted models (OR 1.16,95% CI 1.01-1.34) 3.
Mechanistic Considerations
The worse prognosis with left or codominant circulation in acute settings may reflect less well-balanced myocardial perfusion, particularly when culprit lesions arise from the left coronary system 3. However, this represents a prognostic factor rather than a predisposing factor for developing left main disease.
Clinical Implications
When left main disease is identified, over 80% of patients also have significant (≥70% diameter) stenoses in other epicardial coronary arteries, regardless of dominance pattern 1. The treatment approach—whether CABG or PCI—should be based on anatomic complexity (SYNTAX score), clinical features, and patient preferences rather than coronary dominance 1, 4, 5.