Clinical Presentation
An 81-year-old patient with a medical history of hyperlipoproteinemia, arterial hypertension, and ischemic heart disease presented to the emergency department with symptoms of acute coronary syndrome. The patient had undergone coronary artery bypass grafting (CABG) nine years prior, with a left internal mammary artery (LIMA) graft to the left anterior descending artery (LAD), a left radial artery graft jump from the LIMA to the circumflex artery (Cx), and a venous graft to the right coronary artery (RCA). On presentation, there was a discrepancy in upper extremity blood pressure: 90/65 mmHg in the right arm and 70/40 mmHg in the left arm. Electrocardiography (ECG) revealed sinus rhythm with significant ST-segment elevations (3 mV) in leads V1–V6, I, and aVL.
Initial Diagnostic Workup
Transthoracic echocardiography demonstrated reduced left ventricular systolic function with an ejection fraction of 45%, apical hypokinesia, and grade I mitral insufficiency. Laboratory evaluation showed elevated high-sensitivity troponin T levels at 350 ng/L initially, which rose dramatically to 35,000 ng/L after two hours. Creatine kinase (CK) was 640 U/L, and NT-proBNP was markedly elevated at 25,000 pg/mL, suggestive of acute myocardial injury and volume overload.
Coronary Angiography and Vascular Findings
Emergency cardiac catheterization was performed via the right femoral artery. Angiography revealed a patent venous graft to the RCA and a total occlusion of the left main coronary artery. Additionally, there was an acute thrombotic occlusion of the proximal segment of the left subclavian artery, located before the origin of the LIMA graft, thereby compromising graft flow. This finding identified an extracardiac vascular cause for the myocardial infarction.
Intervention
Percutaneous intervention was undertaken to restore flow in the left subclavian artery. Access was gained through the right femoral artery using a 7 French sheath. The lesion was crossed using a 0.035-inch guidewire, followed by pre-dilatation balloon angioplasty. Given the emergent nature of the situation and the anatomical constraints, a self-expanding stent was selected for ease of delivery and optimal deployment at the target site. Angiographic assessment, including visual analysis and measurement with the pre-dilatation balloon, guided the determination of stent size based on the nominal diameter and vessel dimensions both proximal and distal to the lesion.
Outcome and Follow-up
The post-procedural course was uneventful. The patient remained stable throughout the remainder of the hospitalization and was discharged after one week. Discharge medications included acetylsalicylic acid, clopidogrel, statin, an angiotensin-converting enzyme (ACE) inhibitor, and a beta-blocker. At three-month and one-year follow-up visits, both clinical status and echocardiographic parameters were stable and favorable, indicating successful revascularization and recovery.
