Transient reduction of human left ventricular mass in carnitine depletion induced by antibiotics containing pivalic acid.

OBJECTIVE To study the effect of induced carnitine depletion on myocardial structure and function. SUBJECTS AND DESIGN 7 healthy adult volunteers given 1200 mg pivmecillinam per day for 7-8 weeks were studied by echocardiography before and after 7-8 weeks of treatment and a 15 months follow up after the treatment period. SETTING Teaching hospital. MAIN OUTCOME MEASURES Carnitine concentration in serum, urine, and muscle and echocardiographic measurements. RESULTS After 7-8 weeks of treatment the median free serum carnitine concentration was reduced to 7% and the median total muscle carnitine concentration to 46% of the pretreatment levels. The median diastolic interventricular septum thickness decreased by 14% (mean 26%, P = 0.028) and the median left ventricular mass by 10% (mean 20%, P = 0.018). Fifteen months later these dimensions had increased but not completely returned to pretreatment values. CONCLUSIONS Extended treatment with pivalic acid containing antibiotics causes carnitine depletion which may lead to changes in cardiac structure.