Background: “Vertical” plication of the atrialised chamber in Ebstein malformation has been the subject of debate. A major argument against the procedure is a risk of coronary arterial injury; yet the coronary anatomy in the malformation remains incompletely investigated.

Methods: We examined 17 autopsy hearts with the malformation. Special attention was paid to the course of the posterior descending artery (PDA) on the RV inferior wall relative to the interventricular septum.

Results: The right coronary artery was dominant in 11, while the remaining 6 had left dominance. In 6 hearts with right dominance, the right coronary artery gave rise to PDA before reaching the crux of the heart. This “early take-off” caused the entire PDA to be deviated rightward. Additionally, 2 hearts with right dominant pattern showed rightward deviation of PDA course after an initial short segment along the septum. In 2 hearts with left dominance, the left circumflex artery ran beyond the crux and then gave rise to PDA, again resulting in rightward deviation of PDA. These deviations allowed the PDA to run on the atrialised part of the RV inferior wall where endocardial stitches would be placed during “vertical” plication.

Conclusion: PDA was frequently (10/17, 59%) deviated toward right side relative to the interventricular septum in Ebstein malformation. Together with the thinness of the atrialised ventricular wall, care should be taken to the branch even with superficial endothelial stitches.