Giulio Barbiero,Giuseppe Maiolino,Anna Argiolas,Luca Testolin,Giorgio De Conti

Giulio Barbiero,Anna Argiolas,Giorgio De Conti,Department of Integrated Diagnostic Services,DIDAS,Radiology Unit,University Hospital of Padua,Padua 35128,Italy

Giuseppe Maiolino,Department of Medicine,Medical Clinic 3,University Hospital of Padua,Padua 35128,Italy

Luca Testolin,Department of Cardiac,Thoracic,Vascular Sciences and Public Health,Cardiac Surgery,University Hospital of Padua,Padua 35128,Italy

Abstract BACKGROUND Intra-atrial right coronary artery (RCA) is a rare and generally asymptomatic anomaly of development of the coronary arteries.This malformation could potentially expose the patient to a catastrophic outcome in the case of injury during interventional or surgical procedures.Currently,only a few case reports and no systematic reviews are available in the literature.CASE SUMMARY We report the case of a 54-year-old man with atypical chest pain who underwent multi-detector computed tomography angiography (MDCTA).The exam revealed no significant coronary artery stenoses;however,an intra-atrial course of mid RCA was evident.Medical therapy was administered,and the patient was discharged to home without undergoing a conventional angiography.Previously reported autoptic and clinical cases were retrieved from the PubMed literature database to compare the clinicopathological features of this case.CONCLUSION MDCTA depicted the abnormal course of the coronary artery in this patient as an intra-atrial course of the mid RCA.Finding this abnormality was crucial to avoid an inadvertent injury during interventional or surgical procedures.

Key Words: Coronary artery anomaly;Anomalous course of right coronary artery;Intraatrial right coronary artery;Intracavitary right coronary artery;Multi-detector computed tomography angiography;Case report

INTRODUCTION

Intra-atrial or intra-cavitary course of the right coronary artery (RCA) is defined as a segment of the RCA that courses through the right atrial (RA) chamber[1,2].It is a relatively rare vascular anomaly,with a reported incidence of 0.09%-0.1%[1,2].

Historically,this anomaly of development was most often identified by accident,during coronary surgery or autopsy,due to its benign outcome;however,in the era of multi-detector computed tomography angiography (MDCTA),it is now detected more frequently,and its incidence rate has risen to 1.8%[1].From a radiological point of view,it was defined as a segment of RCA entirely surrounded by intra-atrial contrast in all phases of the cardiac cycle,unlike the myocardial bridge,in which a segment of the coronary artery appears as entirely surrounded by myocardial muscle[1,2].Its recognition is very important before cardiac surgery or endocavitary procedures (i.e.ablation for arrhythmias,catheterization of the RA,and pacemaker implantation) since it carries a concerning potential for injury to the intra-atrial RCA,which could have a catastrophic outcome[1].

Herein,we report the case of a patient with an anomalous course of the RCA through the RA which was identified using MDCTA.Furthermore,to the best of our knowledge,we provide,for the first time,a discussion based on a review of all cases of intra-atrial course of RCA in the literature.The review was conducted according to the guidelines of the Declaration of Helsinki and approved by the Ethics Committee of the University of Padua.

CASE PRESENTATION

Chief complaints

A 54-year-old Caucasian male with moderate cardiovascular risk factors (i.e.,obesity,hyperlipidemia,and hypertension) presented to the cardiologic clinic with atypical angina presenting without dyspnea.

History of present illness

The patient reported that the symptoms had started 2 h before presentation,describing atypical chest pain without dyspnea.

History of past illness

The past history of the patient was unremarkable.

Personal and family history

The patient denied any personal history relevant to atypical angina,dyspnea,or other cardiovascular symptoms and any family history of cardiovascular disease.

Physical examination

On physical examination,the significant vital signs were as follows: body mass index of 28.7 kg/m2;heart rate at regular pulse of 80 beats per min;and blood pressure of 163/92 mmHg.Dyspnea,heart murmurs,and other signs of heart failure were absent.

Laboratory examination

Levels of myocardial injury enzymes (i.e.,troponin T and creatine kinase) were normal.Electrocardiography demonstrated a sinus rhythm of 77 beats per min and absence of ST depression with minimal alterations in lateral repolarization.

Imaging examination

The patient underwent MDCTA (Aquilion ONE;Toshiba Medical Systems,Otawara,Japan) using the following scan parameters: prospective protocol;gantry rotation time of 350 ms;512 × 512 matrix;slice thickness of 0.5 mm with 0.25 mm increments using kernel FC03;automatic exposure control (SURE bExposure 3D;Toshiba Medical Systems) (SD 110 for contrast-enhanced images);and iterative reconstruction.

An intravenous contrast (60 mL Iomeron?400 mg iodine/mL;Bracco Imaging Italy s.r.l.,Milan,Italy) was administrated at 5 mL/s flow.Heart rate was set between 50 and 60 beats per min with intravenous administration of metoprolol.The data were transferred to an external workstation (Vitrea2 FX version 6.3;Vital Images,Plymouth,MN,United States) providing multiplanar reformation (commonly referred to as MPR) and volume rendering technique (commonly referred to as VRT).

From the scans,mild coronary calcification (Agatston calcium score of 34) of the left anterior descending (LAD) coronary artery,without significant stenoses (＞ 70%) of all segments,was detected.Additionally,an abnormal course of the mid RCA was identified.As demonstrated by axial images and CT multiplanar reconstruction,the origin and the proximal tract of the RCA were normal,with an epicardial course in the right atrio-ventricular groove;however,the artery penetrated the anterior RA wall and then exhibited an intracavitary course of 25 mm (Figure 1).After the exit from RA,the RCA passed normally in the atrio-ventricular groove and then continued normally at the level of the diaphragmatic crux.

Figure 1 Multi-detector computed tomography angiography showed the anomalous intra-atrial course of the mid right coronary artery.

FINAL DIAGNOSIS

Considering the patient's medical history along with the MDCTA imaging findings,the final diagnosis was an intra-atrial course of the mid RCA without significant coronary atherosclerosis.

TREATMENT

The patient responded well to standard medical therapy (i.e.,rosuvastatin,administered at 5 mg per day) and was discharged home on postoperative day 2 without having to undergo a conventional angiography study.

OUTCOME AND FOLLOW-UP

At the last follow-up (5 mo postoperatively),the patient was still alive.

DISCUSSION

RCA anomalies are rare and abnormal courses of the RCA are even more rare,with an incidence of 0.1%[2].In the literature,an intra-atrial course of the RCA was reported only in 9 autoptic cases[3,4] and in about 80 clinical cases[1,2,5-26] (Table 1).Most clinical cases were case reports,but a few case series were reported[1,2,5,9,10,16,21].

An intra-atrial course of RCA was first described in 1975 by McAlpine[27].The prevalence of this variant was initially reported to be between 0.09% and 0.1%[5-7],but these rates probably represented underestimations because the conventional angiographic luminographic 2D assessment may not be able to recognize this abnormal variant.The most recent studies - involving cases that are being diagnosed by the new advanced imaging techniques - have reported a prevalence of 1.3%[2] and 1.8%[4];certainly,the increasing use of MDCTA of the coronary arteries will lead to an even greater increase in identification of this anomaly[8].

Reportedly,the segments of the RCA most frequently involving an intra-atrial course were segments 3 (47%) and 2 (40%)[9],with mean length ranging from 14 mm to 53 mm[9].In our perusal of the literature,the most frequent intra-atrial segment of the RCA reported was the mid segment (Table 1),with a length of intra-atrial RCA ranging from 13.2 mm[10] to 55 mm[5].Rarely,the intra-atrial course of the RCA involved segments 1 and 4 (13%)[9] or has lengths shorter (as low as 13 mm) or longer (up to 55 mm)[10-12].

Table 1 Literature summary of intra-atrial course of the right coronary artery

F: Female;M: Male;MDCTA: Multi-detector computed tomography angiography;NR: Not reported;NS: Not specified;PL: Posterior lateral;RFA: Radiofrequency ablation;TAVR: Transcatheter aortic valve replacement;UNK: Unknown;DS: Dual source.

In our review of the literature,most cases were female,and the patient’s ages ranged from 45 years[20] to 78 years[13].In none of the cases was there presence of significant coronary artery stenoses nor were mild atherosclerotic plaques indicated[9].A possible explanation could be the absence of mechanical stress on the segment of the coronary artery when it coursed intra-atrially or intra-myocardially rather than in the epicardial fat,although this conclusion is not definitive[9].

Association between the intra-cavitary course of the RCA and other coronary anomalies have been described,such as with the intramuscular course of the LAD coronary artery or with the anomalous origin of the left circumflex (commonly known as LCX) coronary artery from the right aortic sinus[9].Patients with intra-cavitary course of the RCA were usually asymptomatic,and its discovery was incidentally encountered during an MDCTA coronary study conducted for other reasons (i.e.,atypical chest pain,chest tightness,dyspnea,palpitation,atrial flutter or fibrillation,arrhythmia,fainting,hypotension,or syncope) (Table 1).

An intracavitary course of the RCA has a higher probability of iatrogenic damage than myocardial bridging because of the risk of direct injury at the abnormal vessel segment during surgical manipulation or endoatrial procedures (i.e.,ablation,catheterization,or electrode implantation).Therefore,although it is usually considered an asymptomatic variant,its early recognition is crucial to avoid vessel catastrophic lesions during such procedures[2].

CONCLUSION

MDCTA is a less invasive and less user-dependent method than conventional angiography and can accurately depict the coronary vasculature and its variants of origin,termination,or course[2].The recognition of an intra-atrial course of the RCA by MDCTA could facilitate avoidance of potential hazards during surgical and/or interventional procedures.

FOOTNOTES

Author contributions:All authors contributed to the study conception and design;Barbiero G,Argiolas A,and Maiolino G performed the patient exam;Barbiero G performed the literature review and wrote the first draft of the manuscript;all authors read and approved the final manuscript.

Informed consent statement:Informed written consent was obtained from the patient for publication of this report and any accompanying images.

Conflict-of-interest statement:All authors report no relevant conflict of interest for this article.

CARE Checklist (2016) statement:The authors have read the CARE Checklist (2016),and the manuscript was prepared and revised according to the CARE Checklist (2016).

Open-Access:This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers.It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BYNC 4.0) license,which permits others to distribute,remix,adapt,build upon this work non-commercially,and license their derivative works on different terms,provided the original work is properly cited and the use is noncommercial.See: https://creativecommons.org/Licenses/by-nc/4.0/

Country/Territory of origin:Italy

ORCID number:Giulio Barbiero 0000-0002-1157-3635;Giuseppe Maiolino 0000-0001-6050-1155.

S-Editor:Wu YXJ

L-Editor:A

P-Editor:Wu YXJ