Priya Chudgar DNB1, Nitin Burkule MD DM2, Amol Kulkarni DNB1
Department of Radio Diagnosis1, Department of Cardiology2, Jupiter Hospital, Thane, Maharashtra, India
Clinical History
A 23-year-old male presented to emergency room at night with severe chest pain, lasting for more than an hour, following a day full of heavy physical exertion. On admission, the electrocardiogram (ECG) was normal (Figure 1).
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| Figure 1. A 12 lead ECG performed during hospital admission, showing no abnormality. |
The first sample of serum high sensitivity cardiac troponin I (hs-cTnI) level was normal (< 0.1 ng/ml). The subsequent hs-cTnI showed gradual elevation (3.35 to 19.37 ng/ml, normal <0.1 ng/ml). However, the chest pain subsided on treatment with anti-platelets, low molecular weight heparin, statin and anti-anginals. Coronary angiography was performed the next day, and it was reported to be normal (Movie 1).
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| Movie 1. Cine images (left anterior oblique (A) and right anterior oblique (B)) from catheter angiography reveal normal course and caliber of visualized coronary arteries. No significant luminal narrowing is seen. This was reported as normal. |
CMR Findings
CMR was performed on a 1.5 Tesla Altea (Siemens Healthineers AG, Erlangen, Germany) to investigate the cause of non-ST elevation myocardial infarction with no obstructive coronary disease (MINOCA). The cine balanced steady state free precession (bSSFP) images showed mildly impaired left ventricular function (left ventricular ejection fraction (LVEF) = 41%) and severe hypokinesia of basal inferolateral wall (Movie 2). Short axis cine images were obtained after contrast administration, hence there is alteration in signal intensity.
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| Movie 2. Two chamber (A), four chamber (B), three chamber (C), and short axis stack from base to apical (D-L) cine bSSFP images demonstrate severe hypokinesia of basal inferolateral wall. (Short axis cine images were obtained after contrast administration, hence there is alteration in signal intensity.) |
On T2 weighted short tau inversion recovery (STIR) images and T2 parametric map myocardial edema was present in the basal inferolateral and anterolateral wall (T2 values in normal myocardium: 42.4 ms, basal inferolateral segments: 70.2 ms). Native T1 mapping values and extracellular volume (ECV) in these segments were also elevated (Native T1: 1024 ms, ECV=23.7% in normal myocardium, Native T1:1270 ms, ECV=45.7% in basal inferolateral segments) (Figure 2).
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| Figure 2. Short axis stack in basal, mid, and apical views (A-C, E-G, I-K) and four chamber images (D, H, L) of STIR (A-D), T1 (E-H) and T2 (I-L) mapping show myocardial edema involving the basal and mid-inferolateral walls, with regional increase in T1/T2 values. |
The late gadolinium enhancement (LGE) sequences revealed a near-transmural enhancement in the basal and mid anterolateral and inferolateral segments with microvascular obstruction. These findings confirmed an acute ischemic injury in left circumflex (LCX) coronary territory (Figures 3-4), prompting re-evaluation of the coronary angiogram.
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| Figure 3. Phase sensitive inversion recovery (PSIR) gradient recalled echo (GRE) images short axis stack views reveal near-transmural enhancement in the basal and mid anterolateral and inferolateral segments. Central low-signal intensity foci within the enhanced areas represent microvascular obstruction. These findings are consistent with acute myocardial infarction in the LCX territory. |
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| Figure 4. PSIR GRE images in four chamber stack (A-C), two chamber (D), and three chamber stack (E, F) views reveal near-transmural enhancement in the basal and mid anterolateral and inferolateral segments. Central low-signal intensity foci within the enhanced areas represent microvascular obstruction. These findings are consistent with acute myocardial infarction in the LCX territory. |
Conclusion
On careful review of the catheter coronary angiography, there was paucity of vascular markings in the LCX distribution. There was a subtle contrast hold-up in the LCX territory in the late frames of right coronary artery selective angiogram raising suspicion of an anomalous LCX origin (Movie 3).
CT coronary angiography was subsequently performed, which confirmed an anomalous origin of the LCX from the right coronary artery with a retro aortic course. The vessel showed probable compression along its intramural segment and total thrombotic occlusion of the retro aortic segment. There was partial opacification of LCX in the mid-distal segment (Movie 4 and Figure 5).
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| Movie 3. Selective right coronary artery angiogram demonstrates subtle contrast hold-up in the LCX territory in the late frames, raising suspicion of an anomalous LCX origin. |
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| Movie 4. Axial CT coronary angiogram images show anomalous origin of the left circumflex coronary artery from the right coronary artery with a retroaortic course. There is complete thrombotic occlusion of the retroaortic segment of the proximal circumflex artery. |
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| Figure 5. Reconstructed 3D (A), off axis axial (B), and maximal intensity projections (C-D) CT images confirm anomalous origin of the left circumflex coronary artery (arrows) with complete thrombotic occlusion of its retroaortic segment. The distal segment shows partial opacification. CX = circumflex. RCA = right coronary artery. |
Our patient was managed with optimal medical treatment and no coronary intervention was done in view of the patient being asymptomatic, presence of microvascular obstruction on CMR and more than 24 hours delay for catheter angiography.
However, he was instructed to avoid high intensity exercise and heavy endurance training like running a marathon in future. Clinical follow up is being performed on regular basis.
Perspective
Coronary artery anomalies (CAA) are uncommon, with a prevalence of about 1% in the general population. The clinical significance of these anomalies varies widely depending on the vessel involved and its anatomical course. Interarterial course (course between aorta and main pulmonary artery) is termed as malignant, as it carries high risk of sudden cardiac death.[1]
Anomalous origin of the LCX from the right coronary sinus with a retro aortic course is generally considered a benign entity, in contrast to interarterial course. The significance of this anomaly is that it may cause difficulty in catheterization and interpretation at catheter angiogram. A further clinical significance is that the circumflex artery partially encircles the aortic valve in this course, and may get damaged at aortotomy or it may get compressed following implantation of a prosthetic aortic valve.[2]
The retro-aortic course of LCX is not thought to be hemodynamically significant, as it does not pass between two arterial structures. Nevertheless, rare cases have been reported where so-called benign anomalies resulted in clinically significant ischemic injury.[3] This case demonstrates that under strenuous physical exercise it may be predisposed to ischemia. Mechanical compression of the intramural segment by aortic expansion, particularly during strenuous exertion, may reduce luminal diameter and impair flow. Endothelial damage in the compressed segment can predispose to thrombosis, leading to acute myocardial injury.
This case underscores the importance of considering coronary anomalies in young patients with unexplained myocardial injury and normal angiography. A multimodality imaging approach is essential for accurate diagnosis and management of MINOCA.[4] The presence of an anomalous LCX in the setting of acute coronary syndrome presentation may make a challenging scenario for coronary interventions.
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References:
- Kim SY, Seo JB, Do KH, Heo JN, Lee JS, Song JW, Choe YH, Kim TH, Yong HS, Choi SI, Song KS, Lim TH. Coronary artery anomalies: classification and ECG-gated multi-detector row CT findings with angiographic correlation. Radiographics. 2006 Mar-Apr;26(2):317-33; discussion 333-4.
- Gaudino M, Di Franco A, Arbustini E, Bacha E, Bates ER, Cameron DE, Cao D, David TE, De Paulis R, El-Hamamsy I, Farooqi KM, Girardi LN, Gräni C, Kochav JD, Molossi S, Puskas JD, Rao SV, Sandner S, Tatoulis J, Truong QA, Weinsaft JW, Zimpfer D, Mery CM. Management of Adults With Anomalous Aortic Origin of the Coronary Arteries: State-of-the-Art Review. J Am Coll Cardiol. 2023 Nov 21;82(21):2034-2053.
- Gentile F, Castiglione V, De Caterina R. Coronary Artery Anomalies. Circulation. 2021 Sep 21;144(12):983-996.
- Krishnamurthy R, Masand PM, Jadhav SP, Molossi S, Zhang W, Agrawal HM, Mery CM. Accuracy of computed tomography angiography and structured reporting of high-risk morphology in anomalous aortic origin of coronary artery: comparison with surgery. Pediatr Radiol. 2021 Jul;51(8):1299-1310.
Case Prepared By:
Avanti Gulhane, MD, DNB, FSCMR
Editorial Board, Cases of SCMR
University of Washington