Influence of coronary anatomy and reimplantation on the long-term outcome of the arterial switch.

BACKGROUND: Abnormal coronary artery anatomy is reported to have a significant influence on the outcome of the arterial switch operation. This study examines the impact of coronary anatomy and the occurrence of late coronary obstruction on left ventricular (LV) function and long-term outcome.
METHODS: Coronary artery anatomy, of 170 patients after arterial switch operation (1977-1999), was determined based on operative reports and pre-operative aortograms. Current status was evaluated using ECGs, echocardiograms, scintigraphy, and post-operative coronary angiograms.
RESULTS: In 133/170 patients, coronary artery anatomy consisted of an anterior descending (LAD) and circumflex artery (Cx) from the left sinus and the right coronary artery (RCA) from the right or posterior sinus. The left coronary had an intramural initial course in two of these patients. Fifteen patients had the LAD from the left and Cx and RCA from the right sinus; eight had LAD and RCA from one sinus and Cx from the other; four had single ostium; and three had three separate ostia. Four patients had complex patterns and four patients had a supra commissural coronary. To date, follow-up angiography was performed in 59 patients. Surgical coronary sequellae were found in five patients. Two patients had an occluded left ostium. Initially, they were asymptomatic but showed polymorphic ventricular extrasystoles on ECG and moderate LV dysfunction with large irreversible perfusion defects on scintigraphy. Both patients developed ventricular fibrillation at the age of 14 years. One patient did not survive. The other patient required implantation of a defibrillator. One patient has an occluded RCA, one patient has stenosis of the right ostium and one patient has multiple tortuous collaterals without obstruction of a major branch. In the latter three patients, coronary sequellae were not suspected on ECG, echo, or scintigraphy and were only found on follow-up angiography. Retrograde collateral flow was noted in all three occluded coronaries. LV dysfunction, with normal coronaries, was noted in three patients. All, of these patients, had peri-operative ischaemia suggesting failure of myocardial protection. Two are now asymptomatic with mild LV dysfunction. One patient continues to have severe myocardial dysfunction and secondary aortic insufficiency. A Ross-like procedure was performed placing the original aortic valve in the neo-aortic root. Coronary artery anatomy did not influence early survival or late coronary sequellae.
CONCLUSION: Abnormal coronary anatomy was not a determinant of outcome in our study. Surgical coronary obstruction is independent of original anatomy. It can be almost silent and is potentially fatal. Follow-up angiography must be considered in all patients after the arterial switch operation.