QTc prolongation in apheresis platelet donors

BACKGROUND: Citrate infusion during apheresis procedures can cause lowering of the plasma ionized calcium leading to prolongation of the QT interval and hypotension. At the myocardial level, QT(c) measurement is a sensitive marker of subphysiologic calcium values caused by citrate toxicity. STUDY DESIGN AND METHODS: Seventy-six regular platelet donors were recruited into this study. QT(c) intervals were measured continuously for 3 minutes at four different points during the apheresis procedures. The blood pressure was recorded every 5 minutes throughout the procedure. RESULTS: The baseline QT(c) value for men was 406.5 +/- 13.1 milliseconds(1/2) and for women was 417.6 +/- 13.3 milliseconds' 12 (p = 0.0016). QT(c), prolongation occurred in all procedures in all donors. Maximum recorded values were significantly higher in women than in men (450.8 +/- 20.8 vs. 424.8 +/- 14.3 ms(1/2); p = 0.0025). All QT(c) values returned to baseline by 15 minutes after the procedure. Changes in blood pressure were minimal and no donor experienced severe symptoms. CONCLUSIONS: QT(c) prolongation always occurs during plateletpheresis. This prolongation is greater in women than in men. This study indicates that it may be advisable to assess donors for family or personal history of syncope and family history of sudden death to exclude those at increased risk of arrhythmias because of asymptomatic carriage of a long-QT gene. In addition baseline QT(c) measurement is a simple noninvasive procedure that could be applied to further studies with a view to enhancing donor safety in apheresis.