Sudden Death in a Patient with Left Atrial Myxoma: Report of two cases and review of literature

 

A 55 year old white male with a history of hypertension, hyperlipidemia, smoking and transient ischaemic attacks was admitted to the hospital with worsening dyspneoa on exertion over a period of 6 weeks. He also reported significant weight loss, loss of appetite and fatigue over several weeks. Physical examination revealed tachycardia, and moderate respiratory distress with prominent jugular venous distention. Cardiac auscultation revealed normal S1 and loud P2. Also heard were an early diastolic heart sound ( tumour plop) and a mid-diastolic murmur at the apex. An ECG revealed evidence of left ventricular hypertrophy with repolarization abnormalities. A transthoracic echocardiogram ^{(Figures 1 and  2)} revealed a large, pedunculated, mobile left atrial mass measuring 3x4 cm, impinging on the mitral orifice with a mean gradient across the mitral valve of 15 mm Hg. Left ventricular systolic function was normal.

 

A diagnosis of probable left atrial myxoma was made. The patient had four episodes of syncope within 24 hrs, the first at 3: 53 am after returning from the bathroom,  subsequently leading to cardiac arrest at 14:20 pm.

 

 

He was intubated and initiated on vasopressors.  An emergent Left heart catheterization was performed prior to a referral for surgical excision, which revealed triple vessel coronary artery disease. During cardiac catheterization the patient became more hypotensive requiring an intra-aortic balloon pump.  While arrangements were made for a referral for surgery, the patient’s clinical condition deteriorated rapidly and he went into pulseless electrical activity at 18:54 pm and could not be resuscitated. The patient’s death was presumably due to persistent  intracardiac obstruction.  On autopsy, the left atrial mass was identified as a haemorrhagic left atrial myxoma, 5x4x3.5cm in size attached by a stalk to an inter-atrial septum. Multiple organizsing thrombi were present in the ¹tumour. Histology showed abundant ground substance with stellate myxoma cells and haemosiderin-laden macrophages ^{(Figures 3 and 4)}. The cause of death was attributed to valvular “ball-valve” obstruction.

 

 

 

 

A 57 year old African American female presented with recurrent syncopal episodes and dyspnea on exertion, orthopnea, leg swelling, abdominal distention, loss of appetite and fatigue for the preceding nine months. Physical examination revealed jugular venous distention, a displaced apical cardiac impulse, a parasternal heave, and a loud S2. Also detected were  a pan-systolic murmur at the lower left sternal border, an early diastolic heart sound with a mid diastolic murmur at the apex, bibasilar crackles, ascites, and oedema up to the thighs.

 

Significant laboratory values were a total bilirubin of 1.6 mg/dl, and B- Type Natriuretic Peptide of 1323 pg/ml. A chest x-ray revealed an enlarged cardiac silhouette, right lung atelectasis and effusion. An ECG revealed left atrial and right ventricular enlargement.

 

The patient was admitted with the diagnosis of new onset congestive heart failure and was treated with intravenous lasix, and fosinopril. A 2-D Echocardiogram revealed a large mass suggestive of myxoma in the left atrium measuring 4.5 x 7.5 cm, occupying the entire left atrium protruding through the mitral valve into the left ventricle ^{(Figure 5)} .

 

 

This mass was obstructing flow with a mean trans mitral gradient of 17 mm Hg, with a reduced stroke volume and severe pulmonary hypertension with an estimated Right Ventricular systolic pressure of 120 mm hg.  A presumptive diagnosis of left atrial myxoma was made and the patient was scheduled for its surgical removal the following morning. The patient was transferred to the intensive care unit for closer monitoring; and fosinopril and lasix were discontinued. At about 22:30 hours that night patient was noted to be hypotensive with systolic blood pressure of around 80mm Hg. The patient was treated with normal saline and concentrated albumin. She then developed acute respiratory distress at 23:00 hours requiring intubation and ventilator support. Intravenous dobutamine, dopamine and later norepinephrine were added for continued hypotension. The patient went into pulseless electrical activity, she was successfully coded with a return of her pulse but continued to be hypotensive. Cardiothoracic surgery decided not to take the patient for emergency surgery due to her unstable haemodynamic condition. The patient’s family was notified of the poor prognosis and the decision was made not to resuscitate her if her condition deteriorated further. The patient ultimately became bradycardic and went into asystole at 5: 30 am. An autopsy was not performed. The cause of death was attributed to large left atrial myxoma causing valvular obstruction and cardiovascular collapse.

 

 

These two cases illustrate an uncommon, malignant course of a left atrial myxoma with rapid progression of symptoms which proved fatal.  The most common primary tumour of the heart is myxoma accounting for 40-50% of primary cardiac tumours^(2,3) .Nearly 90% of myxomas occur in the left atrium⁽³⁾ .In over 50% of patients,  left atrial myxoma causes symptoms of mitral stenosis or obstruction. Systemic embolic phenomena are known to occur in 30-40% of patients⁽³⁾ .

 

Table 1. Summary of 17 published cases of sudden cardiac death associated with cardiac myxoma in adults (1950-2008)

NA: not available