Anomalous origin of the right coronary artery. Long term Management of anomalous right coronary artery detected post-cardiac events

Transcription

1 Case Study Long term Management of anomalous right coronary artery detected post-cardiac events Abstract: from the left cusp of the aorta is a rare congenital anomaly with a prevalence of 0.026%. We present two adult cases diagnosed with symptomatic anomalous origin of the right coronary artery. The pathogenesis leading to chest pain or even sudden cardiac death in patients with CAA is contributed to ischemia attributed to the artery pathway or its acute angle takeoff that is susceptible to collapse. The symptomatic CAAs anatomy thus should be inspected in an attempt to prevent further ischemia. Echocardiograms with Doppler, coronary arterial angiography, and CT-coronary angiography are modalities preferred in the diagnosis of CAA. These avoid exposing exertional risk on the CAA patients and each provides a different detection power. Symptomatic CAA,defined as malignant anomalies, will require surgical or medical intervention. Our patients were treated with beta-blockers and with an implantable cardioverter defibrillator as a best mean to avoid the potential life-long risk of ventricular arrhythmias and sudden cardiac death. One patient that developed arrhythmias were treated with a transvenous pacemaker. Keywords: Anomalous Right coronary artery, implantable cardioverterdefibrillator, CT-coronary angiogram

2 Introduction: Coronary arteries anomalies (CAAs) occur in less than 1% of the general population [1]. Anomalies of the right coronary artery (RCA) are particularly rare with an estimated prevalence of 0.026% as reported by Alexander et al in a review of almost 19 thousand autopsies [2]. Kaku et al corroborated this estimate in a series of 17,731 angiograms, detecting RCA anomalies in 44 patients (0.25%) [3]. CAAs can be classified into the following four major categories: 1) Anomalies of course and origin of the artery. 2) Anomalies of intrinsic coronary artery anatomy. 3) Anomalies of coronary termination (which include fistulas). 4) Anomalous anastomotic vessel [4]. RCAs originating from the left sinus were considerably less common than other types of anomalies [1, 4]. CAAs are of clinical importance when they predispose to coronary artery compression which can comprise myocardial blood flow and lead to myocardial ischemia. Fortunately the majority of RCA anomalies are clinically benign and those remain clinically silent [5]. Herein we present two cases of anomalous RCAs. The first case presented with sudden cardiac arrest, the patient was rushed to the catheterization laboratory to intervene the suspected occluded coronary causing his cardiac ischemia. Coronary artery angiogram revealed no visible occlusion. A CT-angiogram revealed the anomalous RCA. The second case presented with a myocardial infarct, angiogram revealed anomalous origin of the RCA. Case 1: A 63-year-old Caucasian male suffered a cardiac arrest while awake in bed. He was on the phone when his wife heard him fall, his family rushed to him and found him unconscious and started compressions. First responders successfully resuscitated him with unsynchronized cardioversion, epinephrine, and amioderone. His airway was maintained with a combitube. Upon arrival to the emergency department he was pale, cool, and diaphoretic. Initial vital signs included blood pressure of 92/71 mmhg, heart rate 100 beats/minute, and temperature was 91.6 degrees Fahrenheit. Pupils were equal, round, and reactive to light. His cardiac physical exam revealed tachycardia but normal rhythem, S1 and S2 present, and no murmurs heard. The rest of the chest exam had normal bronchial sounds, with no wheezing, rhonchi, or rales. The rest of his general physical exam was unremarkable. The EMS ECG did not show any reliable perfusion rhythm and thus was placed on a thumber while in transport to the hospital. His wife was able to provide his medical history which was only significant for a mechanical valvuloplasty couple years ago. In the hospital, his Cardiac troponin remained <0.02 ng/ml (Normal troponin <0.02 gn/ml), total CK was 117 unit/l, and pro-bnp 713 pg/ml. Initial ECG showed minor ST-segment elevation in the inferior elevation in leads II, III, and avf. and STsegment depression in the lateral leads. Fluid resuscitation started, along with amiodarone drip, 2 grams of magnesium, and rectal aspirin. The patient was intubated to support respiration and he started to improve hemodynamically. Thus

3 he was emergently transferred to the cardiac catheterization laboratory for possible percutaneous coronary intervention. Coronary angiography identified a RCA arising from the left coronary cusp superior to the origin of the left main coronary artery (LMCA). The RCA coursed anterior to the aorta (Figure 1). No significant arterial stenosis or atherosclerotic occlusion was identified. The anomalous RCA was further characterized with a computed tomography scan with angiography (CT-angiogram). The CT-angiogram confirmed a cephalic origin of the RCA 8 mm from the origin of the LMCA with a course traveling between the aorta and pulmonary artery (intra-arterial) (Figure 2 and Figure 3). Prior to discharge he received an implantable cardioverter defibrillator (ICD) for secondary prevention of arrhythmias. Case 2: A 60-year-old African-American female with chest pain was transferred from another hospital to our catheterization lab after she was found to have elevated cardiac biomarkers. Her chest pain was typical radiating down her arm and back. Her medical history indicated systemic hypertension and schizophrenia. Her physical exam and review of systems were unremarkable. Initial vital signs upon arrival included blood pressure of 153/105 mmhg, heart rate 80 bpm, temperature of degrees Fahrenheit. Cardiac troponin was 0.83 ng/ml (Normal troponin <0.02 ng/ml). Initial ECG showed sinus rhythm, right bundlebranch block, and no acute changes. She was initially diagnosed with a non STsegment myocardial infarct. Medical treatment was started to lower the heart rate and afterload including beta-blockers, ACE-inhibitors. She was urgently transferred to the cardiac catheterization laboratory for an emergent intervention. Her coronary angiogram revealed the RCA arising from the non-coronary cusp, with an anterior take off, a typical course, and free of occlusive disease (Figure 4A). Angiogram of the left coronary system did not demonstrate any occlusions in the LMCA and the left circumflex (LCX) artery (Figure 4C). She was transfered to the CVICU but developed a second-degree AV block. Beta blockers medication was stopped along with any other AV nodal agents.. The patient symptomatic bradycardia and AV block indicated a need for a pacemaker. We continued transvenous pacing at a rate of 40 The patient was stabilized and was be placed on medical therapy to lower cardiac risks and included Aspirin, Lipitor and ACE-inhibitors. She would be monitored after discharge regarding optimizing her medical treatment further to accommodate her condition. Discussion: The two patients had presented at age of 63 and 60 with no previous reported history of CAA symptoms. Although patients carrying RCA were not reported to have a specific age at presentation, general CAA related pathologies are an important etiology in young patients who suffer SCD [8, 10]. 19% of all SCD were attributed to a multitude of CAA, usually reported in patients suffering cardiac

4 arrest at <35 years of age. Only hypertrophic obstructive cardiomyopathy was responsible for more cases of SCD in this age group. [6-9]. The patient in case two presented with chest related symptoms. Often CAA are clinically silent, if symptoms are present they are typically related to myocardial ischemia and include angina pectoris, myocardial infarction, and heart failure. If myocardial blood flow is compromised, patients become at risk for SCD, which can be the initial manifestation [8]. Other symptoms include palpitations, syncope, and ventricular arrhythmias [11]. It is the presentation of symptoms that designated the RCA in the second case as malignant while the first case malignancy is attributed to anatomy. There are several important anatomical features that predispose patients with CAAs to myocardial ischemia. These malignant features include a course traveling between the aorta and pulmonary artery and the angulation at the coronary artery origin. The first case CT-angiogram revealed a cephalic take off RCA and interarterial course (Figure 2 and Figure 3). The interarterial course carries the highest risk of ischemia, as progressive exertion increases cardiac output which results in dilatation of both the pulmonary artery and aorta [12]. This dilatation of the great vessels causes direct compression, intervening with coronary artery blood flow. Arteries with sharp, acute, or obtuse angles of origin are at risk for collapse leading to subsequent myocardial ischemia [13-15].Anomalies of intrinsic coronary artery anatomy my also result in symptomatic disease. This class of anomalies frequently results in arterial vasospasm. Aside from ischemia secondary to anatomic features of course and origin, patients my experience ischemic symptoms attributed to intrinsic coronary artery anatomy. Although ischemia may not be the presenting symptom from intrinsic anomalies, they predispose patients to more complications (e.g. vasospasms and clots). It is noteworthy, that symptomatic CAAs patients with a history of exerting themselves were more likely to have a course or origin CAA. However, symptomatic CAAs patients without a history of an exertion were more likely to be attributed to vasospasms [15, 16]. It is more noteworthy to implement a non exertion diagnostic modalities to prevent such complication such as stress testing. Diagnostic tests such as coronary angiography that help elucidate symptomatic CAA were often implemented with angina or after a positive stress test [1]. However, all diagnostic tests to be used in CAA patients were limited in giving a measurable sensitivity or specificity. Thus with our high suspicion of CAAs in the first patient after the non-occlusive coronary angiogram, we tried identifying the anatomy and proximal blood flow using more than one radiologic test. Coronary anatomy and blood flow could be delineated through many modalities including echocardiograms with Doppler interrogation (e.g. to examine the anatomy of aortic cusp and blood flow direction), angiography, and/or computed tomography (CT) [17, 18]. Certain tests are more reliable than others, and studies are now advocating toward angiography and CT as a more reliable diagnostic tools over echocardiograms.

5 Coronary angiography was sufficient enough in delineating the RCA in the second patient (figure 4) and showed a higher CAAs detection incidence of 1.07% compared to echocardiography CAAs incidence of 0.17% evident in adult population [1]. The coronary angiography s and echocardiography s ability to detect CAAs where always inferior to the CAAs detection incidence using a CT. CT also had the added ability to detect the origin of the anomalous artery and its course better than coronary angiography and echos. Shi H et al reported they were able to detect a 6.6% of CAAs in a 242 patients using a 16-slice CT [19]. Diagnosis of CAAs and delineation of a malignant anatomy will then require prevention of long term complications after acute treatment. There are many surgical CAAs treatment modalities including but not limited to revascularization. Revascularization may include translocation of the coronary artery, ostioplasty, and bypass grafting. However, both patients were treated medically with beta blockers while trying to assess their surgical candidacy. Medical therapy using beta-blockers have been advocated for and practiced in Japan where surgical therapy of CAA is not common [3, 5]. In addition to preventing the arrhythmogenic complications of CAA, stronger prevention from SCD was also considered in our patients. Reports of successful SCD secondary prevention of ventricular arrhythmias through ICD was evident in the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial as compared to the use of drug therapy with amiodarone. ICD treated group had a relative reduction in mortality by 39% in one year and a reduced relative risk in patients with VF or VT (specifically with EF <0.40) by 33%, showing an overall survival greater than with the amiodarone only treatment group [20]. The Cardiac Arrest Study Hamburg (CASH) with 288 patients randomly allocated to receive ICD, amiodarone, or metoprolol as a secondary prevention of SCD to ventricular arrhythmias also favored ICDs. The CASH study showed that ICD has reduced mortality by 23% (although nonsignificant according to the study) compared to drug therapy was more evident after the first five years [21]. Although both AVID and CASH trials argue in favor of ICD prevention of SCD in ventricular arrhythmias, they did not indicate their patients to have those arrhythmias secondary to CAAs. Clinical trials remain to show a significant mortality reduction through ICD compared to antiarrhythmic drugs in patients at high risk of SCD secondary to ventricular arrhythmias [22]. With that being said, there remains a lack of studies that evaluate ICD's versus medical antiarrhythmic therapy in the secondary prevention of SCD specifically in CAA patients. Conclusion: Malignant CAA lead to myocardial ischemia and long-term heart damage through small ischemic events and/or ventricular arrhythmias prompting life-long intervention. This increased risk of mortality is more specifically worrisome in athletic young population and should prompt cardiologists not to rely solely on one diagnostic test, but to utilize multiple tests when CAA suspicion is high. Both of our CAA symptomatic patients are thus diagnosed with malignant RCAs and were informed with their treatment options. They elected to be placed on both medical

6 therapy (beta-blockers) and ICDs to prevent arrhythmias, and pacemaker to treat arrhythmias. Figures: A B Anomalous Origin of RCA from the left coronary cusp C Metallic aortic Valve with normal motion Anomalous Origin of RCA from the left coronary cusp D LAD LCX Figure 1: Coronary Angiogram of the First Case. RCA arising from the left coronary cusp appears to run anteriorly (A). RCA from a right anterior orientation (B). Dominating Left main artery system with two branches from Left anterior orientation (C). Right anterior orientation of the Left anterior descending and left circumflex arteries (D). (LAD) Left anterior descending. (LCX) Left circumflex. LCX LAD

7 A B PA AA AA DA PA DA Figure 2: Thoracic CT scan from the First Case. T4-T5 CT scan with arrow pointing to the anomalous RCA arising from the left cusp of the Aorta with a malignant course that is interarterial in between the aorta and pulmonary artery (A). T4-T5 CT scan showing the bifurcating of the left dominating system into Left anterior descending artery (arrow) and left circumflex artery (arrow head) (B). (AA) Ascending aorta. (PA) Pulmonary artery. (DA) Descending aorta. Ao RA PA Ao LA LV RV A LV PA LA Figure 3: 3D Reconstructed CT Angiogram of the First Case. B Arrow pointing to the malignant course of the (A). Lateral projection of the heart with arrow pointing to the RCA (B). (Ao) Aorta. (PA) Pulmonary artery. (RA) Right atrium. (RV) Right ventricle. (LA) Left atrium. (LV) Left ventricle.

8 RCA - Anomalous origin from the non-coronary cusp LAD LCX A C LCX LAD B Figure 4: Coronary Angiogram of the Second Case. RCA with an anterior take off and large caliber that is dominant (A). Left main Artery branches, left anterior dominating and Left circumflex in a left anterior orientation angiogram (B). Right anterior orientation showing the small caliber of the left circumflex artery (C). (LAD) Left anterior descending. (LCX) Left circumflex.

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