Anomalous Left Main Coronary Artery in a STEMI Patient

Anomalous left main coronary artery is a variation of the normal coronary artery anatomy that has diverse presentations. Frequently, these variations are discovered incidentally. In this case report, we examined a 47-year-old female who presented with typical anginal chest pain, diaphoresis, and dyspnea, and was diagnosed with ST-segment elevation myocardial infarction (STEMI). Per routine STEMI management, the patient underwent emergent coronary angiography that revealed an occluded right coronary artery (RCA) and an anomalous left anterior descending coronary artery (LAD). Subsequently, we performed an extensive literature review and found this to be an uncommon variant, with one documented case in 2012.  

Case Report

A 47-year-old Caucasian female smoker with a past medical history remarkable for hypertension presented to our hospital with anterior chest wall pain of 10/10 in intensity that happened suddenly at rest in her home and was associated with intense diaphoresis, and bilateral arm and leg numbness. There were no significant vital sign, physical exam, or lab abnormalities. The electrocardiogram (EKG) showed sinus bradycardia with inferior Q waves and reciprocal anterior precordial leads with ST elevation. Cardiac enzymes trended up, with last troponin measuring >200 ng/ml. Cardiac catheterization showed: 1) A 100% distal RCA thrombotic occlusion that received percutaneous coronary intervention (PCI) with a drug-eluting stent (DES) x1; 2) A 70% proximal RCA that received PCI with DESx1; 3) An anomalous left coronary artery (LCA), arising from the right cusp and sharing an ostium with the RCA; 4) A mild non-obstructive distal LAD stenosis (Figures 1-5). Transthoracic echocardiogram (prior to discharge) revealed a left ventricular ejection fraction (LVEF) of 50-55% and inferior wall akinesis.

Following cardiac catheterization, the course of the coronary arteries was further elucidated with coronary computed tomography (CT) angiography (Figure 6) to show that the LAD coursed between the pulmonary artery and aorta, considered a malignant course (Figure 7, course 3) and associated with sudden cardiac death. Subsequently, despite rigorous attempts to reach the patient to address her condition, the patient chose not to follow up with us.

Discussion

Normal coronary anatomy consists of distinct right and left coronary arteries arising from their respective coronary cusps. Deviation of origin of a coronary artery is termed “anomaly of coronary arterial origin.” Such deviations are relatively uncommon in hearts without major congenital cardiovascular malformations. For example, when no coronary arises from the aorta, survival beyond the first year of life is virtually impossible in the absence of compensating pathology when only one coronary arises from pulmonary trunk.¹ 

A broad spectrum of coronary anomalies exist, including coronary ectasia, hypoplasia (possibly contributing to syndrome X), tilted ostia, etc. There are many studies that estimate the incidence of coronary anomalies. For instance, a 1977 review of 1,000 consecutive coronary angiograms performed as part of workup of angina pectoris revealed three cases in which all three major coronary branches arose from the right aortic sinus.² Incidence of coronary anomaly ranges from 0.2% to 1.3% in another study of 12,457 consecutive adult patients undergoing routine coronary angiography, with most common variants being separate origins of the LAD and LCx arising from the left sinus (63.4% of anomalies).³ In that study, an LCA arising from the right coronary cusp (such as seen in the case of our patient) had an estimated incidence of 0.89% of the adult patients with anomalies or 0.01% overall (1 patient of the total 12,457). Yet another study of 18,950 necropsies observed 54 coronary anomalies in total (0.3%), a number consistent with other investigations.⁴ A study of 1950 angiograms showed a total of 0.15% anomalies of the LCA arising from the right cusp or 0.08% total angiograms examined (Table 1).⁵

Statistical definition of normal range includes 99% of presentations in a random population. Anomaly is, therefore, defined as having incidence of ≤1% of cases.⁵ Anomaly by itself does not mandate a disease state, although a pathology can be superimposed on an anomaly; for example, a case of coronary aneurysm secondary to anomalous origin of an RCA from a pulmonary trunk. Hence, clinical classification should endeavor to be pathology-based rather than anatomical. At this time, however, clinical classification is based on anatomical variations that are correlated to clinical symptoms.⁶ Herein lies the danger of over- or under-estimation of anomalous coronary incidence, as the data is drawn from post-mortem analysis of sudden death and myocardial infarction, and discovered incidentally in the course of workup by catheter angiography for symptoms of angina, potentially resulting in a selection bias. Additionally a referral bias in reporting such cases by agencies receiving funding for such reporting is thought to exist.⁶ However, despite evidence implicating coronary anomalies in chest pain, sudden cardiac death, cardiomyopathy, syncope, ventricular fibrillation, and myocardial infarction, the prevailing opinion is that anomalous coronary segments are as vulnerable to obstructive disease as normal segments in the same individual.⁴ 

The incidence of coronary anomalies is important not only for educational purposes, but for public health planning. For example, a series of post-mortem studies of anomalous left coronary artery arising from the right sinus correlates this pathology with approximately 59% mortality before age 20, closely associated with vigorous exertion.⁶ If this percentage is applied to the U.S. population (285,000,000), roughly 16,000,000 individuals (5.6%) would be found to have a coronary anomaly. If 19% of sudden deaths in young athletes are related to these anomalies, the scope of this etiology should become a healthcare priority.⁴

Conclusion

The history of comparative anatomy of coronary vessels is a long and engaging one. However, the discovery of coronary anomalies is incidental to the cases of clinical angina evaluations with coronary artery bypass graft surgery (CABG) and angioplasty, CT arteriography, routine autopsies (1%), and post-mortem cases of sudden cardiac death (SCD) victims (4-15% anomalies).⁶ Given diverse individual outcomes⁷ and a referral bias in reporting them⁶, it is not now possible to establish an accurate number of pathological etiologies. As it is customary in medicine, we hope our report will add to an ever-growing database of cases that can lead to a system of classification to aid in the early diagnosis of and screening for life-threatening coronary anomalies.

References

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2. Baltaxe HA, Wixson D. The incidence of congenital anomalies of the coronary arteries in the adult population. Radiology. 1977 Jan; 122(1): 47-52.
3. Yildiz A, Okcun B, Peker T, et al. Prevalence of coronary artery anomalies in 12,457 adult patients who underwent coronary angiography. Clin Cardiol. 2010 Dec;33(12): E60-E64. doi: 10.1002/clc.20588.
4. Angelini P, Velasco JA, Flamm S. Coronary anomalies: incidence, pathophysiology, and clinical relevance. Circulation. 2002 May 21; 105(20): 2449-2454.
5. Angelini P. Normal and anomalous coronary arteries: definitions and classification. Am Heart J. Feb 1989; 117(2); 418-434. https://dx.doi.org/10.1016/0002-8703 (89)90789-8
6. Angelini P, Villason S, Chan, Jr. AV, et al. Normal and Anomalous Coronary Arteries in Humans. In: Angelini P, ed. Coronary artery anomalies: a comprehensive approach. Lippincott Williams & Wilkins: Philadelphia, Pennsylvania; 1999.
7. Taylor AJ. Anomalous right or left coronary artery from the contralateral coronary sinus: “High-risk” abnormalities in the initial coronary artery course and heterogeneous clinical outcomes. Am Heart J. April 1997; 133(4): 428-435.

Disclosures: The authors report no conflicts of interest regarding the content herein.

Acknowledgements: Special thanks to Dr. Ali Rahimi for his support and guidance.

The authors can be contacted via Dr. Leonid Vasilevskiy, leonid.vasilevskiy@hcahealthcare.com and Dr. Hossein Akhondi, hossein.akhondiasl@hcahealthcare.com.