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the unroofed coronary sinus ( cs ) syndrome is a rare entity ( 1 - 5 ) .
approximately , 75% of cases with the unroofed cs syndrome are associated with a persistent left superior vena cava ( svc ) ( 1 ) .
there is no reported case of an unroofed cs syndrome accompanied by the cs stenosis in the english literature .
the clinical presentation of the unroofed cs is generally determined by the size of the defect between the cs and the left atrium ( i.e. the degree of a left - to - right shunt ) and associated abnormalities ( 2 ) .
we present a case of the complete unroofed cs syndrome with rare associated abnormalities ( i.e. the cs stenosis and a collateral pathway through the small cardiac vein and thebesian vein , but the absence of a persistent left svc ) incidentally identified on coronary computed tomography ( ct ) angiography .
we also propose an explanation of the asymptomatic presentation in this case in spite of the large defect between the cs and the left atrium .
a 43-year - old male presented with intermittent atypical chest pain of one month 's duration .
coronary ct angiography from the tracheal bifurcation to the base of the heart ( lightspeed vct , ge healthcare , milwaukee , wi , usa ) to evaluate the underlying cause of the chest pain demonstrated normal coronary arteries .
however , a large defect ( approximately 2.8 cm in diameter ) between the cs and the left atrium and stenosis of the cs orifice were identified ( figure 1 a and 1b ) . the collateral flow from the cs to the right atrium through the small cardiac vein and thebesian vein
there was no evidence of the enlargement of any cardiac chamber , and nor was there a persistent left svc identified ( figure 1 a and 1b ) .
no abnormality was identified at transthoracic echocardiography , although the ct reading was available to the cardiologist performing echocardiography .
transesophageal echocardiography was not performed because the patient was asymptomatic except for the chest pain .
a diagnosis of the unroofed cs syndrome with the cs stenosis in the absence of a persistent left svc was made .
the unroofed cs syndrome is a rare congenital anomaly that is often associated with a persistent left svc ( 1 - 5 ) .
the classification of the unroofed cs syndrome varies in the literature ( 1 - 5 ) .
it can be classified simply complete or partial depending on the size of the defect between the cs and the left atrium .
no previous report exists of a complete unroofed cs syndrome and absence of a persistent left svc in combination with the cs stenosis leading to a collateral pathway through the small cardiac vein and thebesian vein identified on coronary ct angiography .
this unusual combination of three congenital anomalies remained asymptomatic into adulthood , when the patient presented for unrelated reasons .
the clinical presentation of the unroofed cs syndrome varies from the absence of symptoms to severe right heart failure , and is mainly determined by the size of the cs defect between the cs and the left atrium ( i.e. the degree of left - to - right shunting ) and associated anomalies such as a persistent left svc ( i.e. brain abscess or infarction caused by a right - to - left shunt ) ( 1 - 5 ) .
the present case had no related symptoms in spite of a large defect between the cs and the left atrium .
this was presumably due to the associated cs stenosis and the restriction of the flow by the formation of a collateral flow through the small cardiac and thebesian veins between the cs and the right atrium .
brain abscess or infarction may be a complication in patients with the unroofed cs syndrome due to paradoxical embolism caused by a right - to - left shunt ( 1 ) .
as there was no associated persistent left svc , the possibility of a right - to - left shunt was eliminated .
although the underlying cause of chest pain in the present case was not delineated clearly , the chest pain did not seem to be directly related to the unroofed cs syndrome as it had developed recently without accompanying symptoms . in this instance , multiple detector computed tomography ( mdct ) with its high spatial resolution provided not only precise anatomic detail of the unroofed cs syndrome and the associated anomalies , but also a possible explanation for the patient s clinical presentation . in conclusion , the presence of the cs stenosis and the absence of a persistent left svc in a patient with an unroofed cs syndrome may result in an asymptomatic presentation , even in the setting of a large cs defect .
we describe a patient with an asymptomatic complete unroofed coronary sinus ( cs ) syndrome associated with the cs stenosis in the absence of a persistent left superior vena cava ( svc ) as identified on coronary computed tomography angiography . 
 there was a large defect between the cs and the left atrium ( i.e. a large left - to - right shunt ) , but an unusual combination of the absence of a persistent left svc ( i.e. no risk for brain abscess due to the absence of a right - to - left shunt ) and the cs stenosis ( i.e. a markedly reduced degree of a left - to - right shunt ) , resulting in an asymptomatic presentation .