Classic Coronary Artery Disease in an Unlikely Patient

Abstract

ImageCoronary artery abnormalities are rare, occurring in less than one percent of the U.S. population. (Am Heart J 1989; 117[2]:418.) Anomalous origin of the coronary arteries is a significant problem because 30 percent of these patients experience myocardial infarctions, fatal and nonfatal, and sudden cardiac death. (J Comput Assist Tomogr 2009;33[3]:348.) And anomalous coronary artery origins in the sinus of Valsalva are a major cause of sudden cardiac death for athletes, second only to congenital cardiomyopathy. (Herz 2009;34[4]:268.) Some researchers suggest that in young athletes presenting with a history of syncope or chest pain with exercise, it is important to consider anomalies of the coronary arteries. (J Am Coll Cardiol 2000;35[6]:1493.) Sudden cardiac death due to anomalous coronaries usually occurs during or shortly after exercise (Herz 2009;34[4]:268), and can be the first indication (J Emerg Med 2005;29[4]:437) of anomalous coronaries. But sudden cardiac death secondary to coronary artery anomaly is rare after age 35. (Herz 2009;34[4]:268.) Normal coronary artery anatomy includes the location of the right and left coronary arteries' ostia in the right and left sinus of Valsalva, respectively. The posterior cusp is considered the noncoronary cusp because it does not provide the ostia for any coronary artery. After its origination in the right cusp of Valsalva, the right coronary artery (RCA) travels through the atrioventricular groove, then continues to travel in the posterior interventricular sulcus. The left coronary artery (LCA), after its origination in the left cusp of Valsalva, travels between the pulmonary trunk and the left atrial appendage, and then bifurcates into the anterior interventricular and circumflex arteries. Anomalous origin of the RCA specifically is known to cause myocardial ischemia and sudden cardiac death. (Int J Cardiol 2009;143[3]:e45; J Am Coll Cardiol 2003;42[1]: 148.) The incidence of an anomalous right coronary artery is 0.26 percent. (Int J Cardiol 2008;129[2]:e43.) The right coronary artery originating from the left coronary sinus of Valsalva (ARCAOLS), which accounts for the majority of RCA anomalies (Int J Cardiol 2008;129[2]:e43), has an incidence range of 0.03 percent to 0.71 percent. (Heart Vessels 2005;20[6]:298.) Of the three main subtypes of ARCAOLS (retroaortic, interarterial, and anterior to the pulmonary trunk; J Comput Assist Tomogr 2004;28[2]:293), the most common is interarterial, that is, the path between the aortic root and the pulmonary trunk. The pathway between the aortic root and the pulmonary trunk also is considered a malignant variation because it presents with the highest risk of exercise-induced ischemia and myocardial infarction. (Heart Vessels 2005;20[6]:298; J Am Coll Cardiol 2003;42[1]:148; Int J Cardiol 2009 Apr 22. [Epub ahead of print].) This pathway has an increased incidence of sudden cardiac death (J Invasive Cardiol 2006;18[5]:E152), and is overall the most common anomaly associated with sudden cardiac death. (Rev Cardiovasc Med 2006;7[4]:205.) The etiology of myocardial ischemia due to anomalous coronaries is uncertain, but is proposed to be secondary to spasm of the coronary artery, compression of the artery as it passes between the pulmonary artery and the aorta, and a “flaplike” closure of the artery at its orifice. (J Comput Assist Tomogr 2009;33[3]:348.) Patients with ARCAOLS present with smaller coronary artery ostium with a narrower proximal diameter in comparison with normal anatomy. Also, the angle between its origin and its track to the aorta is more acute. (J Comput Assist Tomogr 2009;33[3]:348; J Am Coll Cardiol 1992;20[3]:640.) Another study suggests that the intussusception of the anomalous artery within the aortic wall (at its origin) possibly leads to ischemia. (Exp Clin Cardiol 2009;14[4]:50.) In a situation with increased cardiac contractility with consequent increase in cardiac output, the smaller orifice and acute angle allows for greater risk for cardiac ischemia. (J Comput Assist Tomogr 2009;33[3]:348.) Symptomatic patients with anomalous coronary arteries should undergo surgical correction. (Herz 2009;34[4]:268.) Transthoracic echocardiography can identify an anomalous origin of coronary arteries. (J Am Coll Cardiol 2003; 42[1]:148.) A recent study supports the use of dual-source computed tomography to determine the diameter changes of the RCA in evaluating myocardial ischemia. (J Comput Assist Tomogr 2009;33[3]:348.) Other studies support the use of magnetic resonance coronary angiography. (Circulation 1995;92[11]:3158.) It is debated, however, whether surgical correction should be done for the patient who has a negative exercise stress test. (Herz 2009;34[4]:268.) It is important to note that ischemia can occur even in asymptomatic patients. (Heart Surg Forum 2009;12[1]:E57.) A 32-year-old woman presented to the emergency department with a chief complaint of chest pain. The pain was intermittent, located midsternal, and had been occurring intermittently for approximately seven hours. The chest pain worsened with exertion, and was relieved by rest. She described the pain as severe and as a pressure. At the time of presentation in the ED, the pain had become constant. The chest pain was associated with diaphoresis, dizziness, and dyspnea. She admitted to having anxiety, but denied having any other significant medical history, including cardiac history, and any similar episodes of chest pain. Both of her parents have hypertension, but there is no history of early onset cardiac disease or sudden cardiac death. The patient denies a history of smoking, alcohol use, or illicit drug use. She works as a lawyer, and is not currently on any home medications. Physical exam yielded stable vitals signs: temperature 98.6 degrees, pulse rate 82 bpm, respiration rate 18 bpm, blood pressure 131/82 mm Hg, and pulse oxygen 100% on room air. She was 5′4″ tall, and weighed 143 pounds. Physical exam was unremarkable. Specifically, cardiovascular exam yielded regular rate and rhythm with no gallops, rubs, or murmurs, and peripheral pulses were intact. No carotid bruits were noted. Lungs were clear to auscultation bilaterally, and there was no chest wall tenderness. No pulsatile masses were noted in the abdominal exam. Complete blood count and complete metabolic profile were within normal limits. Urine drug screen was negative. Cardiac enzymes were negative in the ED. EKG showed NSR, normal axis, with no ST elevation or depression or T wave changes. Chest x-ray showed clear lungs with no acute findings. CTA with calcium score was ordered. The results of this study included the finding of the anomalous origin of the right coronary artery arising from the left coronary sinus. The RCA traveled between the right ventricular outflow tract and the ascending aorta. In addition, the proximal RCA had 60 percent to 70 percent stenosis. Calcium score was 0. The patient was consequently admitted and cardiology consulted. The additional two sets of cardiac enzymes were negative. Cholesterol panel was within normal limits. Per cardiology, there was no evidence of cardiac ischemia. The patient's chest pain completely resolved, and vital signs remained stable. She was discharged the next day with instructions for close follow-up as an outpatient. Cardiac artery anomalies are rare but significant causes of cardiac ischemia and sudden cardiac death, especially in young people. The interarterial pathway of the RCA increases the risks. The reduced diameter of the RCA at its orifice and its acute take-off angle add to risks of ischemia. Our patient presented with the classical presentation of angina. Her age and lack of risk factors made an acute coronary syndrome seem unlikely. Nevertheless, a workup was initiated, and the CTA showed an anomalous RCA with proximal stenosis. This theoretically adds to her risk of cardiac ischemia and sudden cardiac death in that the ARCAOLS is generally already smaller in diameter at the orifice. This patient also had an interarterial pathway (the RCA was located between the right ventricular outflow tract and the ascending aorta), which is considered the most malignant variation of ARCAOLS. Interestingly, the cardiac enzymes and EKG were unremarkable, but this patient does have increased risk of cardiac ischemia. The patient's presentation was classic for coronary artery disease, but her age, gender, and current health status made cardiovascular disease seem unlikely. Nevertheless, an appreciation for accepting the patient's description of her condition led to the diagnosis of an anomalous RCA coronary artery. Although rare, anomalies of the coronary system do occur, and it is prudent for emergency physicians to remember this in their differential diagnosis of chest pain. Dr. Goldman is an emergency physician at Memorial Hospital West in Pembroke Pines, FL; Drs. Apple and Bohorquez are emergency physicians at Mt. Sinai Medical Center in Miami Beach. Return to EM-News.com