Carnitine is involved in transmembrane transfer of long-chain fatty acids into mitochondria. The fatty acids undergo beta-oxidation within the mitochondria in order to generate energy for muscle contraction. A primary carnitine disorder affecting cardiac muscle results in a cardiomyopathy.


Primary disorders of carnitine metabolism often show an autosomal recessive pattern of inheritance. Primary disorders of carnitine metabolism include mutations in OCTN2 carnitine transporter.


A patient who develops a secondary carnitine deficiency may also have onset of heart disease or unexplained worsening of an existing cardiac disorder.


An affected patient may show:

(1) heart failure poorly responsive to standard therapy with diuretics and inotropes

(2) ventricular arrhythmias that can result in sudden death


The patient may have:

(1) cardiac hypertrophy (may be only evidence in a patient heterozygous for a gene mutation inherited as autosomal recessive disorder)

(2) a dilated cardiomyopathy


A patient with a primary or secondary disorder involving carnitine may:

(1) present with an isolated cardiomyopathy

(2) have disorders of both heart and skeletal muscle

(3) have a systemic disorder with cardiac involvement a major or minor component


The possibility of a disorder of carnitine metabolism should be considered:

(1) in children or adults with unexplained heart failure and/or ventricular arrhythmia

(2) if there is a family history of heart failure or cardiomyopathy

(3) if the patient a patient with risk factors for carnitine deficiency develops heart failure or a ventricular arrhythmia


The blood levels of carnitine may be reduced in a patient with a carnitine deficiency. A patient with primary defect in a transport molecule may have normal blood levels.


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