OBJECTIVE To examine physiological and clinical relevance of an anomalous right coronary artery originating from left sinus of Valsalva (right ACAOS) with interarterial course in adults.

METHODS AND RESULTS For physiological assessment, fractional flow reserve (FFR) during dobutamine challenge was measured in 37 consecutive adult patients with lone right ACAOS with interarterial course. At baseline, mean FFR was 0.91±0.06, declining to 0.89±0.06 upon dobutamine infusion (p<0.001). Dobutamine stress FFR was significant (≤0.8) in three patients (8.1%), two of whom were surgically treated. Following surgery, dobutamine stress FFR rose from 0.76 to 0.94 and 0.76 to 0.98. Remodelling index (r=0.583, p=0.002), minimal lumen area (diastole: r=0.580, p=0.002; systole: r=0.0618, p<0.001) and per cent area stenosis (r=-0.550, p=0.004), measured by intravascular ultrasound, correlated with dobutamine stress FFR. To assess the clinical relevance, follow-up data of 119 patients with lone right ACAOS with interarterial course were analysed retrospectively. Two deaths occurred during a median follow-up period of 4 years, for a mortality rate of 0.34 per 100 person-year. No instances of myocardial infarction were recorded and one patient did undergo surgical revascularisation in the course follow-up.

CONCLUSIONS Most instances of lone right ACAOS with interarterial course discovered in adults were physiologically insignificant and ran benign clinical courses. Conservative management may thus suffice in this setting if no definitive signs of myocardial ischaemia are evident.