Risk stratification with exercise N(13)-ammonia PET in adults with anomalous right coronary arteries

In adults with an interarterial and intramural course of an anomalous right coronary artery from the left sinus (AAORCA), surgical unroofing is recommended in the setting of myocardial ischaemia. However, data regarding functional testing are limited, and the management of adults without ischaemia is unclear. To evaluate these patients, we employed an exercise N(13)-ammonia positron emission tomography (PET) protocol. We hypothesised that patients with typical angina and exertional dyspnoea would be more likely to have ischaemia and that patients without ischaemia could be managed conservatively.

Between July 2008 and December 2014, we retrospectively identified 27 consecutive patients >18 years old with an interarterial and intramural course of an AAORCA who had exercise N(13)-ammonia PET.

The majority of patients had anatomic delineation with cardiac CT (25, 93%), and most patients had chest pain (24, 89%). Myocardial ischaemia with PET was common (13, 48%), and ischaemia was more likely in patients with typical angina and exertional dyspnoea (p<0.05). Surgery was performed in 12 patients including 11 patients with ischaemia. At a median follow-up of 245 days, there were no deaths in patients with surgery or in patients managed conservatively.

In patients with an interarterial and intramural course of an AAORCA, typical angina and exertional dyspnoea are associated with ischaemia on exercise N(13)-ammonia PET. Referral for surgical unroofing in symptomatic patients with ischaemia on exercise N(13)-ammonia PET and initial conservative management in patients without ischaemia seems appropriate, though larger studies with long-term follow-up are needed.