Cardiac Myxoma

Commonest primary cardiac tumour in adults (about half of benign primary cardiac tumours), with an incidence of about 0.5 per million per year. Gelatinous, friable or villous, usually pedunculated, derived from multipotent mesenchymal cells.

• Sites: left atrium about 75%, right atrium about 15 to 20%, ventricles about 5%, valves rarely. Atrial tumours arise from the interatrial septum at the fossa ovalis in most cases and prolapse through the atrioventricular valve in diastole.
• Mean age 40 to 60 years, female to male about 2:1. About 5 to 10% are familial. Carney complex (autosomal dominant, PRKAR1A variants) gives multiple recurrent myxomas in any chamber, spotty skin pigmentation (lentigines, blue naevi), primary pigmented nodular adrenocortical disease with Cushing syndrome, growth hormone secreting pituitary adenoma, large cell calcifying Sertoli cell testicular tumours, thyroid nodules, psammomatous melanotic schwannoma and breast myxomas. Familial tumours present younger (20s to 30s) and recur in about 12 to 25%, against 1 to 3% for sporadic tumours.
• Symptoms arise from three mechanisms: valve obstruction (left atrial tumour mimics mitral stenosis, right atrial tumour mimics tricuspid stenosis), embolisation of tumour fragments or surface thrombus, and a systemic inflammatory response driven by interleukin-6.
• Untreated, the risks of stroke, systemic embolism and sudden death are substantial, so excision is urgent once the diagnosis is made.

• Obstructive: exertional dyspnoea, orthopnoea, paroxysmal nocturnal dyspnoea, pulmonary oedema, positional syncope or presyncope (worse on standing or turning), haemoptysis.
  • Left atrial tumour: loud first heart sound, early diastolic "tumour plop" 80 to 120 ms after the second sound, mid-diastolic rumble, apical systolic murmur if the valve is damaged. Sinus rhythm is usual, unlike rheumatic mitral stenosis. Signs change with posture.
  • Right atrial tumour: raised jugular venous pressure, oedema, ascites, cyanosis through a patent foramen ovale, recurrent pulmonary emboli with pulmonary hypertension.
• Embolic (30 to 40%): stroke or transient ischaemic attack, retinal artery occlusion, limb, renal, splenic or coronary embolism, and pulmonary embolism with right sided tumours. Embolised tumour can seed and form cerebral or peripheral myxomatous aneurysms months to years later.
• Constitutional (20 to 40%): fever, weight loss, fatigue, arthralgia, Raynaud phenomenon, rash, clubbing, raised ESR and CRP, anaemia, thrombocytosis or leucocytosis, hypergammaglobulinaemia.
• About 10% are asymptomatic and found incidentally.
• Differential diagnosis: rheumatic mitral stenosis, left atrial thrombus, infective endocarditis with vegetation, systemic vasculitis or lupus (constitutional picture), other cardiac tumours (papillary fibroelastoma, lipoma, angiosarcoma, metastases, lymphoma), cor triatriatum, tricuspid stenosis.
• Complications: stroke and systemic embolism, sudden death from valve obstruction (about 5%), pulmonary hypertension from recurrent pulmonary emboli, mitral or tricuspid valve damage, atrial fibrillation, recurrence, and myxomatous aneurysm.

• Transthoracic echocardiography: a mobile, pedunculated, heterogeneous mass attached to the septum by a stalk, prolapsing through the valve in diastole, with obstruction of inflow (mean gradient measurable). Transoesophageal echocardiography defines the stalk, size, mobility and valve involvement.
• CT or cardiac MRI: tissue characterisation, extent, other chambers, and thrombus versus tumour.
• Before surgery: coronary assessment with CT coronary angiography (preferred) or invasive angiography in men over 40, women over 50 or those with risk factors; avoid left heart catheter passage across a left atrial mass.
• Blood tests: full blood count (anaemia, thrombocytosis), ESR and CRP, immunoglobulins, and blood cultures before any antibiotic if febrile, to exclude endocarditis.
• Brain CT or MRI and vessel imaging after any embolic event, to look for infarcts and aneurysms.
• Histology after excision confirms the diagnosis. Genetic testing (PRKAR1A) when the tumour is multiple, recurrent, in an unusual site, at a young age, or with pigmentation or endocrine features. Echocardiography of first degree relatives if familial.

• Excision is the treatment, and it should be done urgently, usually within days of diagnosis. Medical therapy only bridges.
• Before surgery:
  • Keep the patient at rest and avoid manoeuvres that provoke obstruction. Admit for monitoring if symptomatic.
  • Heart failure: furosemide 20 to 40 mg IV, with careful use because preload is needed to fill past the tumour.
  • Anticoagulation does not prevent tumour embolism and may cause bleeding from myxomatous aneurysms; give it only for atrial fibrillation, thrombus or another firm indication (warfarin to INR 2.0 to 3.0, or apixaban 5 mg twice daily, 2.5 mg twice daily if two of age 80 or more, weight 60 kg or less, creatinine 133 micromol/L or more).
  • Rate control for atrial fibrillation: bisoprolol 2.5 to 10 mg daily or digoxin 0.125 to 0.25 mg daily.
  • Acute stroke: thrombolysis has caused bleeding from myxomatous aneurysms and evidence is limited, so favour mechanical thrombectomy for large vessel occlusion.
• Surgery:
  • Median sternotomy, cardiopulmonary bypass with bicaval cannulation, minimal handling of the tumour, full thickness excision of the septum around the stalk with a margin of about 5 mm, and patch closure of the septal defect with autologous or bovine pericardium. Inspect all four chambers and valves.
  • Repair the mitral or tricuspid valve if damaged; bypass grafting at the same time if coronary disease is present.
  • Minimally invasive and robotic approaches are alternatives in experienced units.
  • Operative mortality is less than 1 to 3%; most patients return to a normal life expectancy.
  • Perioperative antibiotic: cefazolin 2 g IV at induction (3 g if weight over 120 kg).
• Postoperative: aspirin 75 to 100 mg daily is not required routinely; anticoagulation only for another indication. Continue heart failure drugs only if function is impaired. Echocardiography before discharge.
• Carney complex and familial disease: yearly echocardiography for life, urinary free cortisol or low dose dexamethasone suppression test, IGF-1, testicular ultrasound from childhood in males, thyroid ultrasound, and skin review; genetic counselling and screening of first degree relatives (echocardiography every 1 to 2 years).
• Special groups:
  • Pregnancy: excise urgently for obstruction or embolism, ideally in the second trimester, accepting a meaningful risk of fetal loss with bypass; asymptomatic patients may be observed with close echocardiographic surveillance and delivered with a plan for early postpartum surgery.
  • Children: rare, usually Carney complex; surgery is by complete excision with atrial septal repair.
  • Elderly: operative risk is higher but the risk of embolism usually justifies surgery.
• Red flags: syncope, any embolic event, pulmonary oedema, new neurological deficit, sudden collapse.
• Follow up: echocardiography at 6 months, then yearly for at least 5 years in sporadic disease (every 6 to 12 months for 10 years in familial disease), with earlier imaging for any new symptom.