Impaired Flow and Physiology in Coronaries With Anomalous Origin From the Opposite Sinus of Valsalva

BACKGROUND: Anomalous Aortic Origin of a Coronary Artery (AAOCA) high-risk anatomical features (intramural segment, acute take-off angle, slit-like ostium) cause coronary stenosis leading to myocardial infarction. How these features alter coronary physiology remains unclear. AIMS: We aimed to evaluate their impact on coronary blood supply using continuous thermodilution. METHODS: We prospectively enrolled 51 AAOCA patients undergoing continuous thermodilution. Subjects were classified into an ischemic risk (IR) group (intramural segment, acute angle, oval or slit ostium) or non-ischemic risk (no-IR) group. Non-anomalous coronary arteries served as controls. We measured absolute coronary blood flow (CBF) and microvascular resistance. RESULTS: Subjects (median age 48.4 years) presented mostly with angina, syncope, and arrhythmia. Final analysis included 48 AAOCA cases (31 IR, 17 no-IR) and 45 controls. The IR group had a median IM length of 9 mm, take-off angle of 31.9°, and a slit-like or oval ostium. The no-IR group had a median angle of 51.5° and an oval or round ostium. At rest, absolute CBF and microvascular resistance showed no significant differences among groups. However, during hyperemia, the IR group had significantly reduced CBF compared to controls (179 vs. 290 mL/min, p = 0.015). The IR group demonstrated higher microvascular resistance at rest (1473 vs. 1150, p = 0.024) and during hyperemia (433 vs. 305, p = 0.012), indicating persistently increased coronary vascular tone. CONCLUSIONS: High-risk anatomical features of AAOCA are associated with altered coronary physiology. An intramural segment, acute take-off angle, and slit-like or oval ostium are linked to reduced hyperemic coronary blood flow due to increased microvascular resistance.