As a primary suspicion, when a coronary artery disease is seen in a 16-year-old, automatically there is an exclusion of conventional atherosclerosis as the primary driver of the cardiac event. But clinically it becomes a challenge when a teenager arrives with elevated troponin, ST changes and cardiac catheterisation report describing 95% stenosis in the coronary ostia. Thus, the diagnostic challenge becomes unique and mainly hinges on ruling out atherosclerotic causes and exploring inflammatory, autoimmune and other aetiologies. Takayasu arteritis is a large vessel immune-mediated vasculitis that principally effects vessels like the aorta and its major branches. It’s a female-predominant disease and was traditionally described to have an onset before the age of 40 years (1) .What distinguishes this case from prior reports is not the diagnosis itself, but the route by which the diagnosis was established which was by supplementing the clinical diagnosis with histopathological analysis of peri-aortic fatty tissue obtained during off-pump CABG. The tissue showed leukocytoclastic vasculitis which is an active inflammatory pattern involving small vessels in the peri-aortic adventitia, which provided post-surgical diagnostic confirmation of an inflammatory rather than atherosclerotic aetiology. To our knowledge, intraoperative peri-aortic tissue biopsy serving as the diagnostic indication for TA-associated multi-vessel ostial CAD in an adolescent has rarely been described before. We present this case to consider histopathological sampling of peri-aortic tissue during CABG in young patients with unexplained ostial multi-vessel CAD, given its potential to alter post-operative management.

Coronary angiography was performed and revealed coronary artery disease which showed double-vessel disease with left main involvement. • LMCA (Left main coronary artery) Ostial 95% stenosis • LAD (Left anterior descending artery) Ostial 70–80% stenosis, distal mild competitive filling; D1 normal. • LCX (Left circumflex artery) Co-dominant vessel, ostial plaque positive; OM1 normal • RCA (Right coronary artery) Co-dominant vessel, ostial 80% stenosis; PDA and PLV normal. Urgent CABG, or high-risk PTCA to LM and RCA was advised if patient declined the surgical procedure. The exclusively ostial distribution of lesions across all four coronary territories is diagnostically significant. The absence of carotid intimal-medial thickening or plaque, in the context of severe coronary ostial disease, argues strongly against diffuse atherosclerosis as a differential. The cardiac surgical team performed off-pump coronary artery bypass grafting (OPCAB) with intra-aortic balloon pump (IABP) support. The off-pump approach was chosen to minimise aortic manipulation and reduce the risk of embolic complications in the patient. Three grafts were constructed and good flow was established. • LIMA (left internal mammary artery) → LAD (Left anterior descending artery) • RIMA (right internal mammary artery) → Distal RCA • RSVG (reversed saphenous vein graft) → OM (obtuse marginal) IABP was inserted electively in view of tight left main disease. The surgical steps included midline sternotomy, thymus dissection, pericardial opening, LIMA and RIMA harvest with papaverine preparation, radial artery harvest from the left forearm, and SVG harvest from the left leg. Anastomoses were performed on the beating heart using an Octopus III tissue stabiliser with Prolene using continuous running suture technique. A partial side clamp was placed on the ascending aorta for proximal SVG anastomosis. Protamine was used to reverse heparin. Two mediastinal drains were placed. Haemostasis was achieved with electrocautery. The sternum was closed & the patient was shifted to ICU under stable haemodynamic conditions. Two samples were extracted during the surgery, aortic tissue and fatty tissue over aorta. Histopathological evaluation of the fatty tissue sample showed changes of leukocytoclastic vasculitis, whereas the aortic tissue had normal histology and did not show any granulomatous changes. The post-operative course was uneventful. Two units of packed red blood cells transfused. Early extubation and early mobilisation were achieved. Post-operatively Meropenem 1g IV BD was administered. Status post-CABG echo showed normal LV systolic function with EF 62%. Thickened aortic valve with moderate AR was also seen. Vital signs at discharge were normal and the patient was doing well clinically. Discharge medications included Clopidogrel, Furosemide, Atorvastatin, Faropenem & Alprazolam for 5 days. Inj. IV Methylprednisolone was given 3 days post-discharge followed by Tablet Methylprednisolone as a taper for a week. The patient was discharged on post-operative day 7 in a clinically stable condition. She was ambulating, haemodynamically stable (BP 100/60 mmHg, HR 90/min), afebrile, and all surgical wounds were well-healed. She was discharged with instructions to review at CTVS and Cardiology OPD within 5 days. Salt restriction, low-cholesterol diet, fluid restriction to 1.25 litres/day, and no heavy lifting for 3 months were advised.

India had a national estimated prevalence of 2.6 per million of Takayasu arteritis. The mean age of onset in India is 22 years when compared to 25 years in Japan and 35 years in the US.(2) MI in patients under 40 years of age accounts for 2- 10 % of total MI cases, and in patients under the age of 20 years it is remarkably infrequent. This calls for extensive workup to determine non- atherosclerotic causes when patients lack typical risk factors or comorbidities.(3) Angiographic patterns could be the easily discernible diagnostic tests which may help narrow the differential, particularly when faced with distinguishing between atherosclerotic and inflammatory types. (3) Takayasu arteritis is an inflammatory granulomatous vasculitis of medium and large arteries. Histopathological characteristics include transmural fibrous thickening of walls of arteries, resulting in multiple vascular obstructions and ischemic changes.(4) The 1990 criteria to diagnose and classify Takayasu arteritis had 6 conditions and at least 3 of them had to be met - age at onset of disease<= 40 years, claudication of extremities, decreased pulse in the Brachial artery, difference of > 10 mm Hg systolic blood pressure difference between arms, audible auscultatory bruit over subclavian artery or aorta, abnormality in aortograms ( arterial narrowing or occlusion of aorta which is not due to arteriosclerosis, fibromuscular dysplasia, and similar causes.)(5) Later subsequently in 2022, the EULAR classification criteria had absolute requirements and additional imaging and clinical criteria.(6) In the case report by Frovig and Loken, which was one of the earliest documented cases of heart vasculature involvement in a 20 year old lady, its mentioned that it involved coronary ostia or their orifices, though the coronary itself seemed supposedly normal. (7) Coronary involvement is sometimes seen in Takayasu, in young females. There can be acute symptoms which could indicate coronary involvement like chest pain, and this needs prompt work-up to facilitate early diagnosis and treatment. It was observed that the frequency of Myocardial infarction in Takayasu ranged from 3.4% to 24.4% of total cases in a population documented in a current study.(8) .One of the initial clinical manifestations of Takayasu arteritis can also be chest pain suggesting acute Myocardial infarction.(8) Some differentials of Takayasu arteritis include coarctation of Aorta, atherosclerosis, Kawasaki disease(4). The non-atherosclerotic causes of coronary arterial occlusions in women are mainly fibromuscular dysplasia (FMD), spontaneous coronary artery dissection (SCAD), and Takayasu arteritis. These diseases often go unnoticed and undiagnosed and cause serious morbidity and mortality(9). When atherosclerotic causes have been ruled out, it is very important to look at other potential causes of coronary involvement. Vasculitis which involves the coronary include Kawasaki’s disease, Takayasu’s arteritis, polyarteritis nodosa, ANCA-associated vasculitis, giant-cell arteritis and infection related causes which more recently includes Kawasaki-like syndrome associated with SARS-COV-2 infection(10). Histologically, sometimes the tissue sample may lack granulomas which could be indicatory of early phase of Takayasu’s arteritis. Mixed inflammatory and neutrophilic changes can be seen in adventitia in small vasa vasorum(11). This suggests the progressive course of the disease which could eventually lead to ischemic sequelae in different organs secondary to vascular insufficiencies. The revascularisation of ostial stenosis happens on case-by-case basis, and the technique used can be decided based on the severity and the stage of the condition. Commonly used techniques include Coronary artery bypass grafting (CABG), percutaneous transluminal coronary angioplasty with stenting, coronary osteoplasty and endarterectomy among a few(12). We used Off-pump CABG (OPCAB) to treat the stenosis. OPCAB has shown improved selected short-term and mid-term clinical outcomes and resource utilisation(13). Metanalysis showed OPCAB reduces post-operative complications, transfusion requirements and ICU stay compared to the conventional method(13). Aortic regurgitation was found to be present frequently in Takayasu arteritis and serial echocardiography could be justified in these cases to track the progression and severity(14). Corticosteroids are still the main stay treatment options for this inflammatory condition. However surgical interventions are reserved for cases refractory to corticosteroids and/or immunosuppressive therapy(4). Based on a recent article, Childhood Takayasu arteritis (c-TA) is associated with substantial early morbidity and mortality. Younger age at first admission was independently associated with increased risk of rehospitalization or death. Revascularization was associated with fewer subsequent events and disease flares, with approximately a 49% reduction in events and 72% reduction in flares based on the reported effect estimates(15).

A 16-year-old female with NSTEMI, multi-vessel ostial coronary artery disease including 95% LMCA stenosis, aortic regurgitation, severe anemia, and normal carotid arteries on Doppler presented a clinical picture that does not fit conventional atherosclerosis. The diagnosis of inflammatory coronary artery disease was most consistent with Takayasu arteritis & was established clinically & through histopathological analysis of peri-aortic fatty tissue obtained during off-pump CABG, which demonstrated leukocytoclastic vasculitis. Off-pump CABG with IABP support achieved successful revascularisation with an uneventful post-operative course, and corticosteroid therapy was initiated based on the histopathological findings. The case makes a direct argument for considering routine peri-aortic tissue sampling during CABG in young patients with unexplained multi-vessel ostial coronary disease, a simple intraoperative step that can yield a diagnosis that changes the entire trajectory of post-operative care. Patient Consent Written informed consent was obtained from the patient's legal guardian for publication of this case report and accompanying clinical data. Patient identifying information has been handled in accordance with institutional and applicable regulatory guidelines.

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