Acute Type A Aortic Dissection Initially Diagnosed with Myocardial Infarction

Acute type A aortic dissection (AAD) is a potentially fatal condition that requires rapid assessment and treatment. However, a correct diagnosis is not always the rule, as misdiagnosis occurs in less than half the cases [1,2]. Among many conditions, AAD is frequently confused with acute myocardial infarction (AMI), leading to delayed diagnosis and inappropriate treatment with antiplatelet, antithrombin, and fibrinolytic therapies [1]. To determine the percentage of AAD patients initially diagnosed with AMI and analyze the clinical course of these patients, we retrospectively reviewed 78 cases of AAD. From July 2003 to May 2012, 48 men and 30 women admitted to our hospital were eventually diagnosed with AAD. Their age ranged from 26 to 83 years, with a mean of 53.3±16.1 years. Six patients (7.7%, 6/78) were initially diagnosed with AMI (Table 1). Emergency coronary angiography was performed on 4 patients at a mean of 64 minutes after their admission. All 6 patients received thrombolysis. Although a correct diagnosis was delayed in all 6 patients, five underwent operations, that is, all except one (patient no. 4) who died of cardiogenic shock before he arrived at the operation room. Patient no. 3, who also had preoperative cardiogenic shock, underwent an emergency operation right after coronary angiogram without undergoing a thoracic computed tomography. Most of the patients received a large transfusion volume even though they did not undergo re-exploration. Table 1 Details of the misdiagnosed patients In 2010, the American Heart Association and American College of Cardiology released guidelines for early detection of thoracic aortic disease (TAD) [3]. The sensitivity of the TAD guideline diagnostic algorithm has been known to be as high as 95.7% [4]. In our cohort, 3 patients were categorized as an intermediate risk group (risk score 1) and the others were categorized as a high risk of AAD (risk score 2) according to this algorithm. If we had followed the TAD guideline, the misdiagnosis could have been avoided in the high risk patients. However, in the case of the intermediate risk patients, application of this guideline would not have had a significant impact. Since all of the 3 intermediate risk patients had ST segment elevation on electrocardiogram (ECG), they would have been put on the AMI track. Therefore, we believe that some modification is needed in the TAD algorithm; in the intermediate risk group, chest X-ray (CXR) findings such as mediastinal widening should be considered in advance of ECG findings. In our cohort, if patient no. 4 in the intermediate risk group who had a widened mediastinum on CXR had been diagnosed earlier, he would have received a rapid and appropriate treatment. Another concern is about the protocol of AMI-evaluation by the Health Insurance Review & Assessment Service (HIRA). According to this protocol, thrombolytic therapy should be started within 60 minutes and primary percutaneous coronary intervention within 120 minutes after AMI patients arrive at a hospital. This protocol also plays some role in delayed diagnosis of AAD and inappropriate treatment. Therefore, we suggest that a nationwide survey of this misdiagnosis issue be done to modify the HIRA protocol.