Trifurcation of the Right Coronary Artery With Myocardial Bridging of the Posterior Interventricular Artery and the Absence of the Left Marginal Artery: A Report of a Cadaveric Case.

Anatomical variations of the coronary arteries are common; however, the simultaneous occurrence of branching and course anomalies affecting both the right and left coronary systems is rare. This report describes a unique triad of coronary variations observed during the routine dissection of a 50-year-old formalin-fixed male cadaver. The right coronary artery trifurcated in the posterior atrioventricular groove into two distinct posterior interventricular arteries and a continuing atrial branch, with the dominant posterior interventricular artery exhibiting a 5-mm myocardial bridge as it traversed the ventricular musculature before resurfacing. On the left side, the marginal artery branches were absent, and the lateral wall of the left ventricle was supplied by compensatory branches arising from the left circumflex artery and the right coronary artery. While trifurcation patterns are more frequently documented on the left side, trifurcation of the right coronary artery and myocardial bridging of the posterior interventricular artery are considerably less common. These variations have the potential to alter coronary hemodynamics and pose challenges during surgical or interventional procedures, while the observed compensatory collateral supply underscores the adaptive capacity of coronary perfusion. Precise awareness of such rare combined coronary anomalies is essential for cardiothoracic surgeons and interventional practitioners to prevent iatrogenic injury and to accurately interpret atypical patterns of myocardial ischemia.