Abstract
Congenital atresia of the left main coronary artery (LMCA) is one of the rarest congenital anomalies, which may have an unfavorable prognosis leading to myocardial ischemia, ventricle dysfunction or even sudden cardiac death. There are 34 cases of LMCA in adults reported in the literature, most of them successfully treated with coronary revascularization. We report the case of an adult with LMCA who presented with terminal heart failure that required biventricular assistance and heart transplant.
1
Introduction
Congenital atresia of the left main coronary artery (LMCA) is one of the rarest congenital coronary anomalies, classified in the spectrum of coronary ostial stentois or atresia . In contrast with other coronary anomalies, the LMCA may have an unfavorable outcome, leading to severe myocardial ischemia, ventricle dysfunction or even sudden cardiac death if left untreated . An early identification of this entity may enable a rapid therapeutic approach, allowing a better outcome in these patients.
We report the case of an adult with LMCA that presented with heart failure in terminal situation, successfully treated with biventricular assistance and heart transplant.
2
Case report
A 67-year-old man, without risk factors for atherosclerosis, was admitted complaining of rest dyspnea. He had a previous history of dilated myocardiopathy with severe systolic dysfunction, diagnosed ten years before in another city.
The electrocardiogram showed an atrial fibrillation with rapid ventricular rate and right bundle branch block, with severe cardiomegaly on chest X-ray. A transthoracic echocardiogram was performed, showing severe dilatation of the left ventricle with a telediastolic diameter of 81 mm, with global hypokinesia and severe systolic left ventricle dysfunction (the left ventricle ejection fraction was estimated on 15%).
After clinical stabilization of the patient, a coronary angiogram was performed showing the absence of the left coronary ostium, with a dominant right coronary artery (RCA) providing a large collateral vessel to the left side, arising from the conal branch, with an anterior course over the ventricular conus binding the middle left anterior descending artery (LAD), with retrograde filling of the LAD and the left circumflex (LCx) arteries. The LAD and LCx were connected at their origin in the base of a blind pouch, and there was no evidence of significant coronary artery calcification or stenosis ( Fig. 1 ).
In an attempt to decide whether this coronary anomaly per se could produce abnormal perfusion, a cardiac magnetic resonance imaging was performed (limited due to continuous movement of the patient in the setting of severe cardiac insufficiency), showing myocardial ischemia in anterior and lateral territories ( Fig. 2 ).
A cardiac computed tomography was planned in order to assess the path of the collateral vessel and complete the anatomical study, however, the patient presented a progressive clinical worsening that led to refractory cardiac insufficiency requiring vasoactive drugs support and the implantation of an intra-aortic balloon pump. Finally, a biventricular assist device was required, as a bridge to cardiac transplantation that was successfully performed two months after the episode. The anatomic findings during heart transplantation confirmed the suspected diagnosis of LMCA, showing a blind-ended dump at the LM ostium.
2
Case report
A 67-year-old man, without risk factors for atherosclerosis, was admitted complaining of rest dyspnea. He had a previous history of dilated myocardiopathy with severe systolic dysfunction, diagnosed ten years before in another city.
The electrocardiogram showed an atrial fibrillation with rapid ventricular rate and right bundle branch block, with severe cardiomegaly on chest X-ray. A transthoracic echocardiogram was performed, showing severe dilatation of the left ventricle with a telediastolic diameter of 81 mm, with global hypokinesia and severe systolic left ventricle dysfunction (the left ventricle ejection fraction was estimated on 15%).
After clinical stabilization of the patient, a coronary angiogram was performed showing the absence of the left coronary ostium, with a dominant right coronary artery (RCA) providing a large collateral vessel to the left side, arising from the conal branch, with an anterior course over the ventricular conus binding the middle left anterior descending artery (LAD), with retrograde filling of the LAD and the left circumflex (LCx) arteries. The LAD and LCx were connected at their origin in the base of a blind pouch, and there was no evidence of significant coronary artery calcification or stenosis ( Fig. 1 ).
In an attempt to decide whether this coronary anomaly per se could produce abnormal perfusion, a cardiac magnetic resonance imaging was performed (limited due to continuous movement of the patient in the setting of severe cardiac insufficiency), showing myocardial ischemia in anterior and lateral territories ( Fig. 2 ).
A cardiac computed tomography was planned in order to assess the path of the collateral vessel and complete the anatomical study, however, the patient presented a progressive clinical worsening that led to refractory cardiac insufficiency requiring vasoactive drugs support and the implantation of an intra-aortic balloon pump. Finally, a biventricular assist device was required, as a bridge to cardiac transplantation that was successfully performed two months after the episode. The anatomic findings during heart transplantation confirmed the suspected diagnosis of LMCA, showing a blind-ended dump at the LM ostium.
3
Discussion
LMCA is a rare condition with very few reported cases, particularly in the adult age . In pediatric patients, LMCA frequently coexists with other cardiac anomalies, such as supravalvular aortic stenosis, ventricular septal defect, pulmonary stenosis, prolapse of mitral valve or patent ductus arteriosus; leading to a worse prognosis, with early symptoms in the pediatric age .
In adult patients, the prognosis is determined by the collateral circulation development, with some rare cases revealed as asymptomatic findings in the elderly age .
In adult-onset cases, a differential diagnosis with single coronary artery and atherosclerotic stenosis of the left main ostium must be always considered. We summarize the anatomical details that allow the identification of this entity.
3.1
Differential diagnosis with acquired stenosis of LM
By definition, LMCA is congenital, however, in some clinical adult cases, it can be difficult to determine whether the defect was present since birth. The absence of atherosclerotic risk factors may support the diagnosis of LMCA, however, it is not conclusive.
In LMCA, the presence of only one or two full-diameter connecting collateral vessels (without narrowing at the transition) is suggestive of congenital origin. In contrast, in cases of postnatal acquired collateral vessels, a rich network of channels that involves the septal, infundibular and atrial branches is usually present. Such acquired collateral vessels enlarge progressively after birth and are typically smaller than the distal recipient vessels (“step-up phenomena”).
3.2
Differential diagnosis with single coronary artery
LMCA must also be distinguished from single coronary artery. Although in both conditions the RCA supplies the entire coronary circulation, in LMCA the perfusion to left-sided arteries occurs retrogradely, in a centripetal way (from the periphery to the center); while in the single coronary artery the blood flows from the center to the periphery with a centrifugal flow. Anatomically, the LMCA is characterized by the absence of a left main trunk that may sometimes be present in a rudimentary form; whereas a normal left main trunk is patent in cases of single coronary artery anomaly ( Table 1 ).
| LMCA | Single Coronary artery |
|---|---|
| Collateral vessels from conal system or distal RCA. | Absence of collateral circulation. |
| Centripetal blood flow | Centrifugal blood flow |
| Absence of LM (sometimes present in a rudimentary form) | Patent LM |
| Frequent association with other cardiac anomalies | Rare association with other cardiac anomalies |
| Surgical revascularization is the more frequent therapy | Conservative management frequently performed |
| Bad prognosis if untreated | Good prognosis |
Embriologically, LMCA may suggest that regression of the left main trunk has taken place after elongation of the coronary artery anlage has started, and the mechanism may be different from single coronary artery, which may reflect displacement of the left main trunk anlage during rotation of the trunchus arteriosus, in an earlier stage of life. This allows a better compensation of the coronary flow in the cases of single coronary artery, usually presented as casual findings in the literature .
In the present patient, the absence of a left main trunk and the presence of a 2 full-diameter connecting collateral branch from the conal system without the previously described “step-up phenomenon” are suggestive of congenital origin of the ostial atresia.
3.3
Revision of the literature
There are 34 cases of LMCA in adults reported in the literature , summarized in Table 2 ; 44% of them were men, with a mean age of 54.4 ± 14.2 at the diagnosis. The first one was wrongly reported as single coronary artery in 1967 .
| Author, year | Sex | Age | Onset symptoms | Anatomic findings | Treatment | Evolution | C. Pattern | Ref |
|---|---|---|---|---|---|---|---|---|
| Murphy, 1967 | M | 71 | Angina | Reported as single coronary artery | Diagnosed in autopsy | Non cardiac death | 1 | |
| Fortuin 1971 | M | 60 | SCD | Diagnosed in autopsy | Diagnosed in autopsy | SCD | 1 | |
| Vidne, 1979 | M | 52 | Angina | Surgery | Surgery | Good | 2 | |
| Vidne 1979 | F | 50 | Angina | Surgery | Surgery | Good | 2 | |
| Dymond, 1980 | F | 38 | Angina | Collateral circulation from posterior descending | Surgery | Asymptomatic 4 months after surgery | 2 | |
| Leivo, 1987 | F | 76 | Asymptomatic | Conal branch between aorta and pulmonary artery | Diagnosed in autopsy | Non cardiac Death | 1 | |
| Beretta, 1990 | F | 49 | Angina | Collateral circulation from posterior descending | Surgery | Asymptomatic 20 months after surgery | 2 | |
| Carosio, 1991 | F | 64 | Angina | Collateral circulation from posterior descending and left auricular branch | Surgery | Not reported | 2 | |
| Ruiz, 1992 | F | 48 | Angina | Collateral circulation from posterior descending | Surgery | Asymptomatic 6 months after surgery | 2 | |
| Bedogni, 1992 | F | 43 | Angina | Collateral circulation from posterior descending | Surgery | Good | 2 | |
| Ghosh, 1993 | M | 56 | Angina | Coronary artery atherosclerosis | Surgery | Good | 1 | |
| Musiani, 1993 | M | 44 | Angina | Coronary artery atherosclerosis | Surgery | Good | 1 | |
| Musiani, 1995 | F | 68 | Dyspnea, heart failure | Collateral circulation from conal branch | Surgery | Good | 1 | |
| Rodríguez, 1998 | M | 55 | Angina | Collateral circulation from conal branch Coronary artery atherosclerosis | Surgery | Good | 1 | |
| Elian, 2003 | M | 42 | Asymptomatic (positive scintigraphy) | Collateral circulation from descending posterior and posterolateral | Clinical treatment | Asymptomatic 18 months after clinical treatment | 2 | |
| Elian, 2003 | M | 23 | Effort syncope. Positive stress test | Little collaterals from descending posterior | Surgery | Asymptomatic 30 months after surgery | 2 | |
| Nishida, 2005 | M | 34 | Diagnosed in autopsy (SCD) | Independent origin of the conal branch with an acute angle and interarterial course between the aorta and pulmonary trunk | Diagnosed in autopsy | SCD | 1 | |
| Nishida, 2005 | M | 82 | Diagnosed in autopsy (Incidental finding) | Independent origin of the conal branch with anterior path | Diagnosed in autopsy | Non cardiac death | 1 | |
| Nicol, 2007 | M | 72 | Angina | Independent origin of conal branch | Not reported | Not reported | 2 | |
| Nicol, 2007 | M | 76 | Angina | Conal branch coursing between pulmonary trunk and aortic root Coronary atherosclerosis | Not reported | Not reported | 1 | |
| Nicol, 2007 | M | 62 | Incidental finding | Conal branch with interarterial course | Not reported | Not reported | 1 | |
| Levisman, 2009 | M | 53 | Angina | Conal branch with retroaortic course | Not reported | Not reported | 1 | |
| Duarte, 2009 | F | 61 | Chest pain | Conal branch with anterior course | Not reported | Not reported | 1 | |
| Chou, 2009 | F | 32 | Heart failure | PDA 2 large conus arteries originating separately from RCA | Surgery of the PDA, conservative treatment of the LMCA | Needed to be reoperated 5 years after | 2 | |
| Saito, 2009 | M | 48 | LV dysfunction | Posterolateral branch Hypoplasic LAD | Surgery | LV function recovery | 2 | |
| Saremi, 2011 | F | 67 | Angina and dyspnea | Conal branch (retroartic conal ring) | Not reported | Not reported | 1 | |
| Shen, 2012 | F | 37 | HF and angina (LV dysfunction) | Patent ductus arteriosus corrected 5 years before 2 large Conal branches Supraortic membrane covering LM origin | Surgery | NYHA I one month after the surgery | 2 | |
| Graidis 2012 | M | 65 | Atypical chest pain and positive stress test | Collateral circulation from sinus node branch and posterolateral branch | Medical treatment | Asymptomatic 3 years after clinical treatment | 1 | |
| Sayin2013 | M | 65 | Dyspnea and positive stress test | Conal branch described as “intercoronary communication” | Surgery | Not reported | 1 | |
| Numasawa 2013 | F | 65 | Heart failure (LV dysfunction) | Collateral circulation from posterior descending | Medical treatment | LV function recovery | 2 | |
| Tanawuttiwat, 2013 | M | 59 | Angina | Conus branch Coronary artery atherosclerosis | Surgery | Good | 1 | |
| Tanawuttiwat, 2013 | M | 77 | Asymptomatic (positive Scintigraphy) | Collateral circulation from posterior descending Coronary artery atherosclerosis | Medical treatment | Good | 1 | |
| Nicolini, 2014 | M | 51 | Incidental finding (Aortic regurgitation study) | Conal branch Supraortic membrane covering the LM origin | Combined Surgery | NYHA class I one month after surgery | 1 | |
| Rubio, 2015 | M | 72 | Incidental finding (Aortic stenosis study) | Conal branch with independent origin and anterior path | Surgery of the Ao valve, conservative treatment of the LMCA | Asymptomatic one year after | 1 |
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