Symptoms may occur or at any time, but most often they accompany a change of body position. Symptoms may include:

• Shortness of breath with activity
• Breathing difficulty when lying flat
• Breathing difficulty when asleep
• Dizziness
• Fainting
• Sensation of feeling your heart beat (palpitations)
• Chest pain or tightness

The symptoms and signs of left atrial myxomas often mimic mitral stenosis.

General symptoms may also be present, such as:

• Cough
• Fever
• Involuntary weight loss
• General discomfort (malaise)
• Joint pain
• Blueness of skin, especially the fingers (Raynaud's phenomenon)
• Fingers that change color upon pressure or with cold or stress
• Curvature of nails accompanied with soft tissue enlargement (clubbing) of the fingers
• Swelling - any part of the body

These general symptoms may also mimic those of infective endocarditis.

Listening to the heart with a stethoscope, the doctor may hear a "tumor plop" (a sound related to movement of the tumor), abnormal heart sounds, or murmurs. These findings may change when the patient's body changes position.

The first diagnostic test is usually an echocardiogram (a test based on ultrasound waves to view the heart), often accompanied with a Doppler study. The echocardiogram allows visualization of the myxoma, cardiac valves and heart structure. Other tests include:

• Chest X-ray
• CT scan of chest
• Heart MRI
• Left heart angiography
• Right heart angiography

An ECG may demonstrate atrial fibrillation.

Laboratory tests which may be altered include:

• A complete blood count (CBC), which may show anemia, decreased platelet count, or elevated white blood cell count (WBC).
• Elevated ESR (erythrocyte sedimentation rate)
• Elevated interleukin-6 (IL-6)
• Altered levels of proteins, such as protein C and gammaglobulins.