Left Anterior Descending Coronary Artery Occlusion Secondary to Blunt Chest Trauma
A 17-year-old young man was setting off fireworks on July 4th when the base of the artillery shell blew off and struck him in the chest, knocking him to the ground. An ECG obtained in the emergency room at a local hospital showed 4-mm ST-segment elevation in leads V1 through V5, I, and aVL with pathological Q waves, complete right bundle-branch block, and a left anterior hemiblock (the Figure). Computed tomography scan of the chest revealed a comminuted sternal body fracture with a retrosternal hematoma, right-sided pneumothorax, and bilateral pulmonary contusions (the Figure). Laboratory data showed a creatine kinase of 9884 U/L, creatine kinase-MB of 846 ng/mL, and troponin T of 92 ng/mL. A transthoracic echocardiogram showed a markedly reduced left ventricular ejection fraction of 25% with hypokinesis of the distal septum and apex, normal right ventricular size and function, mild aortic, mitral and tricuspid regurgitation, and no pericardial effusion. He was managed conservatively for myocardial contusion. Because of hemodynamic instability and failure to wean off the ventilator, the patient was then transferred to our institution for further management 2 weeks after initial presentation.
ECG and echocardiographic findings led us to perform a coronary angiogram that revealed a totally occluded large proximal left anterior descending coronary artery after the first diagonal branch (the Figure). Other coronaries were normal. A transesophageal echocardiogram showed mild eccentric regurgitant jets in the mitral (the Figure) and tricuspid valves resulting from ruptured chordae with severe global left ventricular dysfunction (ejection fraction, 25%). Afterload reduction therapy for heart failure with intravenous vasodilators was initiated, and the patient was weaned off the ventilator. Mechanical recanalization of the infarct-related artery was not performed, but an implantable cardioverter-defibrillator was placed for prevention of sudden cardiac death. He was discharged home in a stable condition on a β-blocker and an angiotensin-converting enzyme inhibitor.
Acute coronary artery occlusion following blunt chest trauma is a rare complication. Our case highlights the importance of having a high index of suspicion for coronary occlusion following blunt chest injury. The artery most commonly involved is the left anterior descending coronary artery.1 The causative mechanisms of coronary occlusion after blunt chest trauma are hypothesized to involve crushing of the artery between the sternum and the spine, vascular spasm, dissection with thrombus formation, or rupture of an existing plaque with thrombus formation. Cardiac contusion can present similarly with elevated cardiac enzymes and ECG and transesophageal echocardiogram abnormalities suggestive of myocardial infarction.2 This indicates the significance of having a strong clinical suspicion of coronary occlusion to make a decision regarding emergent coronary angiography in patients presenting with blunt chest trauma.