In polymyositis, which is true: ECG (electrocardiogram) changes, EEG (electroencephalogram) changes, or SGOT (serum glutamic-oxaloacetic transaminase) changes?

From the Guidelines

In polymyositis, SGOT (serum glutamic-oxaloacetic transaminase) changes are true. Polymyositis is an inflammatory myopathy that primarily affects skeletal muscles, causing muscle inflammation, weakness, and damage. As muscle tissue breaks down during the disease process, muscle enzymes including SGOT (now more commonly called AST or aspartate aminotransferase) are released into the bloodstream, resulting in elevated serum levels. These enzyme elevations are a characteristic laboratory finding in polymyositis and are used in diagnosis and monitoring disease activity, as noted in the management guidelines 1. While cardiac involvement can occur in polymyositis and might occasionally lead to ECG abnormalities, as seen in a study where 13 out of 20 patients with polymyositis had abnormal ECGs 1, this is not as consistent or characteristic as SGOT/AST elevation. EEG changes are not typically associated with polymyositis as the disease does not primarily affect brain function. The elevation of muscle enzymes, including SGOT/AST along with other markers like creatine kinase (CK), aldolase, and lactate dehydrogenase (LDH), reflects the ongoing muscle damage and serves as an important diagnostic and monitoring tool in managing polymyositis, with guidelines suggesting the use of these markers for evaluation and monitoring 1. Key points to consider in polymyositis diagnosis and management include:

• Muscle weakness is more typical of myositis than pain
• Blood testing to evaluate muscle inflammation, including CK, aldolase, and transaminases (AST and ALT)
• Consideration of cardiac testing such as ECG and echocardiogram or cardiac MRI for myocardial involvement
• Autoantibody testing to evaluate possible concomitant conditions
• Use of inflammatory markers and other diagnostic tools as needed for individual cases.

From the Research

Polymyositis Characteristics

• The condition is characterized by chronic inflammation in skeletal muscle, leading to muscle weakness and other symptoms.
• Various studies have investigated the effects of corticosteroid therapy on polymyositis, including changes in muscle function and inflammatory markers 2, 3.

ECG Changes

• Electrocardiographic abnormalities have been found in patients with polymyositis, including left anterior hemiblock and right bundle-branch block 4.
• A study comparing ECG findings in patients with dermatomyositis and polymyositis found that one-third of patients had ECG abnormalities, with a higher prevalence in polymyositis than dermatomyositis 5.
• Common ECG abnormalities in polymyositis include left ventricular hypertrophy, left atrial enlargement, and rhythm and conduction abnormalities, such as left anterior fascicular block 5.

SGOT Changes

• Serum glutamic-oxaloacetic transaminase (SGOT) levels have been found to be elevated in patients with polymyositis, with a significant decrease in SGOT levels in polymyositic muscles 6.
• The levels of serum SGOT have been correlated with the severity of muscle weakness and have been used as a marker of disease activity 6.

EEG Changes

• There is no evidence to suggest that EEG changes are a characteristic of polymyositis.
• The studies reviewed focused on ECG changes, muscle function, and inflammatory markers, but did not investigate EEG changes 6, 2, 3, 4, 5.