arrhythmia vs cardiac arrhythmia

arrhythmia and cardiac arrhythmia both are nouns.

Word	Noun	Adjective	Verb	Adverb
arrhythmia	Yes	No	No	No
cardiac arrhythmia	Yes	No	No	No

As nouns, arrhythmia and cardiac arrhythmia are synonyms defined as:

arrhythmia and cardiac arrhythmia: an abnormal rate of muscle contractions in the heart

arrhythmia (noun)	cardiac arrhythmia (noun)
an abnormal rate of muscle contractions in the heart	an abnormal rate of muscle contractions in the heart