Objective: Carnitine deficiency has been associated with progressive cardiomyopathy due to compromised energy metabolism. The objective of this study was to investigate clinical features of carnitine deficiency-induced cardiomyopathy and the therapeutic efficacy of L-carnitine administration.
Method: Between January 2010 and December 2011, filter-paper blood spots were collected from 75 children with cardiomyopathy. Free carnitine and acylcarnitine profiles were measured for each individual by tandem mass spectrometry (MS/MS). For those in whom carnitine deficiency was demonstrated, treatment was begun with L-carnitine at a dose of 150 - 250 mg/(kg·d). Clinical evaluation, including physical examination, electrocardiography, chest x-ray, echocardiography and tandem mass spectrometry, was performed before therapy and during follow-up.
Result: Of 75 cardiomyopathy patients, the diagnosis of carnitine deficiency was confirmed in 6 patients, which included 1 boy and 5 girls. Their age ranged from 0.75 to 6 years. Free carnitine content was (1.55 ± 0.61) µmol/L (reference range 10 - 60 µmol/L). Left ventricular end-diastolic diameter (LVDd) was (5.04 ± 0.66) cm and left ventricular ejection fraction (LVEF) was (38.5 ± 10.5)%. After 10 - 30 d therapy of L-carnitine, free carnitine content rose to (30.59 ± 15.02) µmol/L (t = 4.79, P < 0.01). LVDd decreased to (4.42 ± 0.67) cm (t = 4.28, P < 0.01) and LVEF increased to (49.1 ± 7.6)% (t = 6.59, P < 0.01). All patients received follow-up evaluations beyond 6 months of treatment. Clinical improvement was dramatic. LVEF returned to normal completely in all the 6 patients. LVDd decreased further in all the 6 patients and returned to normal levels in 3 patients. No clinical signs or symptoms were present in any of the 6 patients. The only complications of therapy had been intermittent diarrhea in 1 patient.
Conclusion: Tandem mass spectrometry is helpful to diagnose carnitine deficiency and should be performed in all children with cardiomyopathy. L-carnitine has a good therapeutic effect on carnitine deficiency-induced cardiomyopathy.