MISSED DIAGNOSIS OF ACUTE TYPE A AORTIC DISSECTION TREATED AS NON-ST ELEVATION MYOCARDIAL INFARCTION: A TEACHABLE MOMENT

Abstract

TOPIC: Cardiovascular Disease TYPE: Medical Student/Resident Case Reports INTRODUCTION: Acute type A aortic dissection (ATAAD) is a life threatening emergency, with a mortality rate of 1% to 2% per hour during the first 24 to 48 hours, reaching 75% at 2 weeks and 91% at 1 year, if left untreated. CASE PRESENTATION: A 35-year-old male, nonsmoker with a history of untreated hypertension (HTN), presented with sudden onset, severe, non-radiating, "twisting" mid-sternal chest pain. Initial vital signs showed an elevated blood pressure (BP) to 210/132 mmHg in both arms, heart rate 85 beats/minute, afebrile and arterial saturation of 100% on room air. He was in severe distress due to chest pain and sweating profusely. The cardiac examination did not reveal a murmur, rub or gallop, his radial pulse was regular, and equal bilaterally. Electrocardiogram (EKG) showed sinus rhythm with T-wave inversions in inferior and lateral leads. Initial work up was significant for an elevated creatine kinase (CK) 636 U/L (normal range < 200 U/L). Chest X-ray did not reveal cardiomegaly, mediastinal widening or infiltrates. CT aortic dissection including iliac arteries - chest, abdomen and pelvis with and without contrast was read as negative for dissection, aneurysm, pulmonary embolism or pericardial effusion. Subsequent labs were significant for up trending CK of 751 U/L (normal range < 200 U/L) and Troponin 0.42 ng/ml (normal range < 0.10 ng/ml). In view of rising cardiac biomarkers, dual anti-platelets and anticoagulants for acute coronary syndrome (ACS) were started. A transthoracic echocardiogram (TTE) was ordered which was performed 12 hours later and showed dissection flap in proximal ascending aorta, moderate eccentric aortic regurgitation, and bicuspid aortic valve. DISCUSSION: Some reports of CT scanning in acute dissection have reported sensitivities close to 100%, but false negative scans are well recognized. True sensitivity is likely lower at 94% to 100% and specificity around 77% to 100%. False negative results can be secondary to a reader's error or a true false negative image. Second imaging tests are frequently obtained in cases of suspected aortic dissection, with transthoracic or transesophageal echocardiography being the most commonly used modality. Point of Care Ultrasound (POCUS) has become commonplace in many critical care settings, studies have shown good sensitivity and specificity for the diagnosis of ATAAD [5]. This may allow the treating clinician to diagnose an acute aortic dissection at the point of care, avoiding the clinical and time dissociation inherent to consultative echocardiography. Intimal flap visualization has a sensitivity of 67-80% and a specificity of 99 - 100%. CONCLUSIONS: Our case is a reminder that the sensitivity of CTA to rule out acute aortic syndrome is not 100% and second diagnostic modality should be used if clinical suspicion is high. The pre-test probability of a diagnosis should dictate the type of imaging/testing warranted and its urgency. REFERENCE #1: Afifi RO, Sandhu HK, Leake SS, et al.: Determinants of Operative Mortality in Patients With Ruptured Acute Type A Aortic Dissection. Ann Thorac Surg. 2016, 101:64-71. 10.1016/j.athoracsur.2015.07.007 REFERENCE #2: Abbas A, Brown IW, Peebles CR, Harden SP, Shambrook JS: The role of multidetector-row CT in the diagnosis, classification and management of acute aortic syndrome. Br J Radiol. 2014, 87:20140354. 10.1259/bjr.20140354 REFERENCE #3: Wang Y, Yu H, Cao Y, Wan Z: Early Screening for Aortic Dissection With Point-of-Care Ultrasound by Emergency Physicians: A Prospective Pilot Study. J Ultrasound Med. 2020, 39:1309-15. 10.1002/jum.15223 DISCLOSURES: No relevant relationships by SYED ABBAS, source=Web Response No relevant relationships by Syeda Hamadani, source=Web Response No relevant relationships by Seth Koenig, source=Web Response, value=Honoraria Removed 05/16/2021 by Seth Koenig, source=Web Response No relevant relationships by Seth Koenig, source=Web Response, value=Honoraria Removed 05/16/2021 by Seth Koenig, source=Web Response No relevant relationships by Abeer Zeeshan, source=Web Response