Cardiac myxoma is a rare, benign primary cardiac neoplasm with an incidence of 0.09% among patients at a hospital-based cardiology unit.¹⁾ It frequently occurs in the left atrium of the heart.²⁾ Atrial myxoma remains an elusive diagnosis since it is almost always an incidental finding.²⁾ Electrocardiogram (ECG) abnormalities are uncommon in the presence of atrial myxoma.³⁾ However, suspicious serial changes in ECG patterns could play a role in the detection of an atrial myxoma at a primary care setting.

A 71-year-old lady presented with an abnormal ECG finding during a scheduled primary care appointment. She was asymptomic and had a history of type 2 diabetes mellitus, essential hypertension, and dyslipidemia. During the consultation, the ECG reading showed premature ventricular contraction at a 1:1 ratio (ventricular bigeminy) with a heart rate of 46/min (Figure 1). Her ECG from the previous year (Figure 2) showed non-specific changes, possibly related to early left ventricular hypertrophy. The recorded vital signs were as follows: blood pressure, 159/74 mm Hg; heart rate, 62/min; and respiratory rate, 18 breaths/min. On physical examination, heart murmurs were not audible and other findings were unremarkable. The laboratory findings were: glycated hemoglobin, 7.1%; urea, 10.0 mg/dL; creatinine 1.0 mg/dL; Na⁺, 137 mEq/L; and K⁺, 3.6 mEq/L. In order to rule out secondary causes that could have led to the changes in the ECG, various blood investigations were ordered. An urgent appointment was scheduled a week later to review these results. The patient was also advised to seek urgent medical attention if she felt palpitations or giddiness. During the second consultation, a week later, the repeat ECG showed atrial flutter with a 3:1 atrioventricular block (Figure 3). All the results of the blood investigations were normal (thyroid stimulating hormone, 4.26 µIU/mL; Na⁺, 135 mEq/L; K⁺, 4.4 mEq/L; corrected Ca²⁺, 8.9 mg/dL; PO^4-, 0.32 mg/dL; hemoglobin, 12.9 g/dL; and white blood cell count, 7.4×10³/µL), except for an elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels (88 mm/h and 9.8 mg/L).

Urgent transthoracic echocardiography revealed a dilated left atrium and ventricle without any myocardial hypokinetic changes. A large echogenic mass measuring 3.1×4.1 cm was identified at the left atrium (Figure 4). The mass was solid and appeared pedunculated, arising from a stalk at the endocardium. The patient had a left ventricular ejection fraction of 54%. The patient was immediately referred to a tertiary care cardiology clinic where a second transthoracic echocardiography was performed. An imaging diagnosis of left atrial myxoma was confirmed. The tumor measured approximately 2.9×3.1 cm. A paroxysmal atrial fibrillation pattern was observed on the ECG. Warfarin treatment was initiated while aiming for a target international normalized ratio between 2 and 3. Currently, the patient is jointly cared for by the primary care physician and a multidisciplinary team that is helping to manage the anticoagulation therapy. The patient is unwilling to undergo surgery to remove the tumor.

Atrial myxoma is common in middle-aged women; women are affected twice as often as men.^2,4,5) Although the origin of cardiac myxomas is uncertain, 10% of cases are familial.²⁾ Familial type atrial myxomas can take the form of genetic myxoma syndromes such as the Carney complex.^4,6) Depending on the size, site, and lesion composition, clinical presentation in patients can range from no symptoms to heart failure.²⁾ Cardiac examination in patients with left atrial myxoma might reveal an early diastolic tumor plop, apical diastolic murmur, changes in pre-existing murmurs, gallop rhythm, or modification of the first (split) or second heart sound.³⁾

ECG findings may be nonspecific in 20% to 40% of patients.⁷⁾ The most common ECG finding is left atrial hypertrophy (35%), followed by repolarization disorders (21%), conduction disorders (24%), and rhythm disorders (9%).³⁾ Atrial fibrillation and atrial flutter are rare in left atrial myxoma.³⁾ Chest radiograph findings are non-specific, and include pulmonary interstitial marking, congestive heart failure signs, non-specific cardiomegaly, and left atrial enlargement.³⁾ Calcification linked to the tumor and pleural effusions are unusual.³⁾

Blood investigations might reveal an elevated ESR, CRP level, and white blood cell count.^4,8) Transthoracic echocardiography should be performed on all patients with suspected atrial myxoma.⁵⁾ Cardiac myxoma can be diagnosed without further imaging if echocardiography confirms the presence of a mobile mass attached to the endocardial surface by a stalk arising from the fossa ovalis.⁷⁾

In conclusion, suddent changes in ECG (especially if a previous ECG shows sinus rhythm) coupled with an elevated CRP ir ESR levels should prompt the clinician to rule out cardiac myxoma through transthoracic echocardiography. An urgent referral to a cardiologist is warranted if there is clinical presentation of an infected myxoma, systemic embolization, or non-specific constitutional symptoms.