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symptoms of cardiac involvement of tumor result from the location and impingement on adjacent structures .
conduction disturbances due to several kinds of cardiac tumor such as primary rhabdomyosarcoma,1 ) malignant melanoma with cardiac metastasis,2 ) cardiac hemangioma3 ) and metastatic adenocarcinoma of lung4 ) were reported previously .
mesotheliomas of the atrio - ventricular ( av ) node also cause heart block and sudden death.5 ) however , cardiac involvement of leiomyosarcoma is very rare .
a 54-year - old man was referred to our electrophysiology laboratory because of dizziness and dyspnea .
he was diagnosed with leiomyosarcoma of the right lower leg and received wide excision at another hospital 5 years ago .
recently , the patient was in good physical condition for 2 years and no abnormal findings were detected on the surface electrocardiography ( ecg ) 2 years prior .
however , the current ecg revealed complete av block and idioventricular escaped rhythm of bifascicular block morphology suggesting infrahisian block ( fig .
the patient underwent cardiac magnetic resonance imaging , which revealed huge interventricular mass ( 6735 mm ) from base to apex with low signal intensity , similar to the myocardium on the t1-weighted image ( fig .
2a ) and mild higher signal intensity , as compared with the myocardium on the t2-weighted image ( fig .
trans - thoracic echocardiography revealed normal left ventricular ejection fraction ( lvef 60% ) and no hemodynamic compromise .
dual chamber permanent pacemaker was implanted on the second day of admission and we placed a right ventricular ( rv ) lead toward free wall of rv apex that was confirmed by fluoroscopy and echocardiography because of tumor invasion in the septum of rv apex .
there were no procedure - related complications , however , ventricular tachycardia ( vt ) developed 3 days later .
twelve - lead ecg showed wide qrs complex tachycardia , left bundle branch block pattern with left superior axis morphology and late transition , which is compatible with vt from rv apex ( fig .
3 ) . administered amiodarone and  - blocker suppressed further events of vt and the patient was discharged uneventfully .
he received pazopanib for palliative chemotherapy , which was stopped due to hepatic toxicity and poor performance status .
the patient passed away after 3 months of pacemaker implantation due to progression of underlying disease and multiple organ failure .
there are only a few sporadic case reports of arrhythmic presentation in patients with cardiac involvement of leiomyosarcoma .
atrial fibrillation due to metastasis to pulmonary vein and left atrium,6 ) ectopic atrial tachycardia with right atrial leiomyosarcoma7 ) and vt due to local tumor growth in the right ventricular outflow tract8 ) were reported previously .
this was the first case report of a large metastatic mass of leiomyosarcoma located on the entire interventricular septum causing complete av block . furthermore , there are no previous reports of cardiac involvement of tumor that caused both bradyarrhythmia and tachyarrhythmia .
the patient was treated with implantation of permanent pacemaker for the management of complete av block and anti - arrhythmic drug suppressed vt successfully .
pacemaker mediated tachycardia or pacemaker - induced vt was considered because of subsequent development of vt after pacemaker implantation without prior history of vt . however ,
12-lead qrs morphology of vt was different from that of paced ventricular rhythm ( fig .
4 ) and apical septum of rv due to tumor invasion was suspected as the origin .
pacemaker interrogation excluded pacing - induced vt or pacemaker - mediated tachycardia ( fig . 5 ) .
there was no histopathological diagnosis of cardiac lesion , however , we diagnosed the mass as a malignant metastasis because of the simultaneous similar pattern of widespread metastatic lung lesions with prior histopathologic confirmation of metastatic malignant leiomyosarcoma .
complete surgical resection of cardiac mass was not feasible because of infiltrative growth in the entire interventricular septum .
pacemaker implantation and anti - arrhythmic medications were started for symptomatic relief . upgrade to implantable cardioverter defibrillator ( icd ) was considered regarding underlying structural substrate for vt .
however , vt was well controlled with anti - arrhythmic drug and overall mean survival time in patients with metastasizing soft tissue sarcoma is approximately only 10 months despite therapy.9 ) thus , upgrade to icd was not performed and our patient passed away 3 month later due to disease progression cardiac metastasis should be considered when the patient with previously known leiomyosarcoma complains of cardiac symptom .
clinicians should be aware that both bradyarrhythmia and tachyarrhythmia could develop in patients with cardiac metastasis of malignant leiomyosarcoma .
we described a case of a 54-year - old male who presented with dizziness and dyspnea due to cardiac metastasis of leiomyosarcoma . 
 cardiac metastasis of leiomyosarcoma caused both bradyarrhythmia and tachyarrhythmia in the patient . 
 he was treated with implantation of a permanent pacemaker for management of complete atrio - ventricular block and anti - arrhythmic drug that suppressed ventricular tachycardia successfully .