Typical angina with an atypical diagnosis

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A 39-year-old woman complained of exertional substernal chest pressure. The pressure occurred in a typical pattern after 20-25 minutes of aerobic exercise and resolved within several minutes of rest. She denied any palpitations, syncopal episodes, or chest pressure at rest. Despite her symptoms, she continued her thrice-weekly aerobic workouts. Earlier, another physician had diagnosed costochondritis and prescribed a trial of anti-inflammatory medications. The woman's symptoms persisted, however, and after several months, she sought another evaluation in our clinic. Her past medical history was most notable for breast augmentation surgery. There was no family history of coronary artery disease (CAD) or sudden cardiac death. Social history was positive for ongoing tobacco use, approximately one pack per day for 20 years. She took no chronic medications.

1. EXAMINATION FINDINGS

Vital signs were notable for a BP of 120/80 mm Hg and pulse 20 beats per minute. Head, eyes, ears, nose, and throat were unremarkable. No jugular venous distension or carotid bruits were detected on neck examination. Cardiovascular exam showed regular rate and rhythm with no murmurs, gallops, or rubs. Lungs were clear to auscultation in all fields. Extremities were negative for any clubbing, cyanosis, or edema. Neurologic exam was nonfocal. ECG showed a normal sinus rhythm, with no ST-wave changes or other abnormalities. Chest x-ray was unremarkable.

2. ALL'S WELL, EXCEPT…

Because of her persistent symptoms, the patient underwent an exercise thallium myocardial perfusion scan. She was able to exercise for 12 minutes on a standard Bruce protocol, remaining asymptomatic even after achieving 97% of her maximum heart rate with 12.5 metabolic equivalents. The images showed an anterior-wall defect with minimal reversibility thought likely to be related to breast-attenuation artifact. Minimal ischemia due to this defect was possible, although other etiologies seemed more likely and warranted consideration.

Coronary angiography revealed a rare and unexpected finding: No CAD was seen, but the ostium of the right coronary artery (RCA) was not visualized, indicating an anomalous origin. This was further evaluated with CT angiography, which showed the RCA originating from the left anterior cusp. The proximal 1 cm of the RCA had a slitlike narrowing when compared with the rest of the artery (see Figure 1).

3. DISCUSSION

Anomalous coronary arteries are a rare anatomical variant with an incidence of approximately 1%.1 Most anomalies are not clinically significant, and a majority of patients have no symptoms. When present, initial symptoms can include syncope and angina. Occasionally, the first indication of a problem is sudden cardiac death.

In young athletes who suffer sudden cardiac death, anomalous coronary arteries are among the most common causes. Inherited coronary anomalies have been associated with a higher incidence of congenital heart disease than acquired anomalies but do not appear to be associated with a higher risk of coronary arteriosclerosis.2

As was the case in our patient, an anomalous RCA commonly has a slitlike ostium, potentially leading to ischemia. Compression of the artery from larger vessels is also a postulated cause of ischemia. Unfortunately, studies have shown standard cardiac testing, including ECG and stress ECG, to be largely ineffective in detecting ischemia associated with anomalous arteries.3

Typically, during the course of an evaluation, the abnormality is identified by catheter-based angiography. In recent years, two noninvasive imaging techniques, magnetic resonance and CT angiography, have been used to improve evaluation, better delineate the three-dimensional course of the anomalous vessel, and better define its relation to surrounding structures.4-6

Different corrective surgical methods have been studied, depending on the specific vessel, including minimally invasive single-vessel bypass using the mammary artery.7

4. BACK TO NORMAL

The patient underwent single-vessel coronary artery bypass of the RCA, using the mammary artery, without complications. She slowly returned to her regular aerobic workouts without her prior exertional symptoms and continues to do well.

Dr. McElhannon is assistant professor of family medicine, Scott & White Hospital and Clinics, Texas A&M University System Health Science Center, in Temple, Tex.

References

1. Garg N, Tewari S, Kapoor A, et al. Primary congenital anomalies of the coronary arteries: a coronary:arteriographic study. Int J Cardiol. 2000;74:39-46.

2. Topaz O, DeMarchena EJ, Perin E, et al. Anomalous coronary arteries: angiographic findings in 80 patients. Int J Cardiol. 1992;34:129-138.

3. Basso C, Maron BJ, Corrado D, Thiene G. Clinical profile of congenital coronary artery anomalies with origin from the wrong aortic sinus leading to sudden death in young competitive athletes. J Am Coll Cardiol. 2000;35:
1493-1501.

4. McConnell MV, Ganz P, Selwyn AP, et al. Identification of anomalous coronary arteries and their anatomic course by magnetic resonance coronary angiography. Circulation. 1995;92:3158-3162.

5. Budoff MJ, Ahmed V, Gul KM, et al. Coronary anomalies by cardiac computed tomographic angiography. Clin Cardiol. 2006;29:489-493.

6. Datta J, White CS, Gilkeson RC, et al. Anomalous coronary arteries in adults: depiction at multi-detector row CT angiography. Radiology. 2005;235:812-818.

7. Reul RM, Cooley DA, Hallman GL, Reul GJ. Surgical treatment of coronary artery anomalies: report of a 37 1/2 year experience at the Texas Heart Institute. Tex Heart Inst J. 2002;29:299-307.

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