A 35-year-old woman with a history of preeclampsia three years earlier presented with new-onset severe left arm pain and pain on the left side of her face. She said it had started about two hours before presentation, and was so extreme that it took her breath away. She also said it felt a little like her symptoms with preeclampsia. She wasn't pregnant and had no trauma or prior injury. The rest of her review of systems was negative.
Her blood pressure was 200/140 mm Hg and then 160/120 mm Hg when repeated three minutes later. She had a heart rate of 85 bpm, a respiration rate of 20 bpm, and oxygen saturation of 96% on room air. She was tearful and appeared anxious. She had an otherwise normal physical exam, and her pain was not reproducible. Her first ECG is shown. Prior ECGs were not available for comparison.
What is your differential diagnosis? How do you want to manage this patient?
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Diagnosis: Spontaneous Coronary Artery Dissection
Spontaneous coronary artery dissection has likely been underdiagnosed and unappreciated as a cause of acute coronary syndrome until recent years. The actual incidence of the disease is uncertain, but it is the etiology of approximately 1.7 to four percent of all patients presenting with ACS who get angiography. It is also estimated that SCAD is responsible for 0.5 percent of all sudden cardiac deaths. (Trends Cardiovasc Med. 2018;28:340.)
A tear develops spontaneously between the tunica intima in the coronary vessel and the rest of the vessel wall. The growing hematoma obstructs the true lumen of the vessel, leading to ischemia distal to the occlusion. The left anterior descending was the most affected vessel in one study, followed by the left circumflex and the right coronary. (Catheter Cardiovasc Interv. 2017;89:1149; http://bit.ly/2NUlQY1.) SCAD is a nonatherosclerotic process, and does not involve plaque rupture into the vessel wall leading to obstruction, which makes it a disease under myocardial infarction with nonocclusive coronary arteries, a general classification that has received more attention in recent years.
One aspect of SCAD that makes it difficult to diagnose is that it is primarily a disease of healthy young women. Approximately 85 to 90 percent of cases are found in women, and the average age of diagnosis is 42 to 52. It is also estimated that SCAD is the etiology of MI in around 25 percent of women under 50. (Catheter Cardiovasc Interv. 2017;89:1149; http://bit.ly/2NUlQY1.) Coronary angiography is the primary means of diagnosis, and some young women with SCAD do not go on to angiography because of a lack of risk factors and atypical symptoms that make it less likely for them to be worked up for ACS.
Not surprisingly, there are no robust guidelines or risk stratification tools for this diagnosis. A study by Luong, et al., found that 96 percent of patients presented with chest pain, 50 percent with pain radiating to the arm and 23 percent with nausea or vomiting. (Catheter Cardiovasc Interv. 2017;89:1149; http://bit.ly/2NUlQY1.) This is difficult to interpret, however, because they looked at patients who had been diagnosed with SCAD and retrospectively evaluated their charts for historical features of their presentation.
Not surprisingly, there are no robust guidelines or risk stratification tools for the diagnosis. Besides pain, a couple of other historical features are worth noting on patient evaluation. Some data suggest that a significant emotional stressor before the event or a maximal-type physical exertion with the Valsalva maneuver can be identified. (Trends Cardiovasc Med. 2018;28:340.) Pregnancy has long been associated with SCAD, and coronary dissection is a significant etiology of ACS in pregnant patients, who comprise between eight and 18 percent of patients ultimately diagnosed with SCAD. Other risk factors include known or suspected fibromuscular dysplasia, other connective tissue disorders, and hormone replacement therapy. (Heart. 2017;103:1043.)
The most important step is to appreciate SCAD as a potential diagnosis, especially in this nontraditional cohort of patients for an ACS workup. SCAD remains uncommon, so not all healthy young women need an ACS workup, but it should be considered in the correct clinical settings. Troponin, electrocardiogram, complete blood cell count, basic metabolic panel, and chest radiograph should be part of the regular cardiac workup, plus any additional tests as indicated by history or exam. One study found that 24 percent of patients with SCAD presented with STEMI, and the rest were diagnosed with non-STEMI, but these numbers vary across available data. (Catheter Cardiovasc Interv. 2017;89:1149; http://bit.ly/2NUlQY1.) A small percentage of patients present with ventricular dysrhythmias. (StatPearls. May 6, 2019; http://bit.ly/2NTX1eB.)
SCAD is diagnosed primarily by angiography, although other less invasive means of evaluation are under investigation, including cardiac MRI and coronary CT. Three different types of patterns that are diagnostic can be seen on angiography. These patterns can sometimes be challenging to appreciate during angiography, and some are likely missed. The treatment for SCAD is initially conservative except in cases with persistent significantly impaired blood flow or hemodynamic instability. Several studies showed that patients who received immediate percutaneous coronary interventions did worse than those under conservative management, and most but not all patients go on to make a complete recovery without intervention. Close observation during the acute phase of the disease is important because of the risk of progression. (Heart. 2017;103:1043.)
Managing traditional cardiac risk factors and initiating usual treatment in the setting of persistent ventricular dysfunction (beta blockers, ARB, etc.) is recommended for the long term. Anticoagulation and antiplatelet therapies are not thought to be beneficial, and female patients on hormone therapy at the time of their dissection are encouraged to use nonhormonal forms of birth control. Around 80 percent of patients had an underlying arteriopathy, most commonly fibromuscular dysplasia or another inflammatory process such as inflammatory bowel disease or connective tissue disease, so an outpatient workup for etiology of dissection is frequently warranted. (StatPearls. May 6, 2019; http://bit.ly/2NTX1eB.)
Our patient went emergently to the cath lab. She had evidence of coronary artery dissection of her left anterior descending artery. She did not receive PCI at the time, but had a peak troponin of 19 ng/mL. She was evaluated for arteriopathies, and was diagnosed with fibromuscular dysplasia with renal artery involvement. Her ECG at one month is shown. She continues to follow up with cardiology.
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Dr. Barrettis an assistant professor of emergency medicine at the University of Colorado School of Medicine in Aurora and an attending physician at Denver Health Medical Center. She is also an associate medical director for the Denver Health Paramedic Division and the medical director for the paramedic school. Read her past columns athttp://bit.ly/EMN-QuickConsult.