Electrocardiographic abnormalities during recovery from ultra-short opiatedetoxification

The aim of this study was to detect electrocardiographic ab,abnormalities d uring recovery from ultra-short opiate detoxification, using a retrospectiv e study design conducted at a university hospital. Twenty-two consecutive p atients (mean +/- SD, age 30.0 +/- 6.3 years) receiving daily oral methadon e underwent ultrashort opiate detoxification under general anaesthesia. In the post-anaesthetic stages they received oral clonidine and naltrexone, an d in some cases trimipramine was dispensed. Heart rate, rate-corrected QT i nterval (msec) and repolarization abnormalities of 12-lead electrocardiogra phic recordings before and after detoxification were examined. The serum el ectrolyte concentrations (mmol/l) including Na+, K+ and Ca2+ were assessed. Eighty-one ECGs were evaluated in total. Compared to the initial values, h eart rate was significantly lowered in the first two tracings after detoxif ication (median values 60.0/m\in. vs. 52,5/min; p = 0.0006). The lowest hea rt rate measured after detoxification was 44/min. The cQT interval was sign ificantly lengthened (median value 420 msec vs. 453 msec after detoxificati on). In 16 tracings (20%) taken from 10 patients (45%) cQT rose above 460 m sec and in two tracings (2%) it copped 500 msec. Modest hypokalaemia (2.9-3 .5 mmol/l) was linked to cQT prolongation (greater than or equal to 460 mse c) in 10 ECG tracings. Spearman's correlation coefficient indicated that pr olonged cQT intervals correlated with decreased potassium values. Twelve tr acings (15%) taken from 10 patients (45%) after detoxification showed T-wav e inversion and in two cases sinus rhythm was turned into a rhythm arising from the atrioventricular node. Serum potassium was significantly lowered ( median values 4.3 v.s 3.8 mmol/l, p = 0,0001). The Ca2+ concentration fell significantly (2.4 vs. 2.2 mmol/l, p = 0,0001) but not below the normal ran ge. It was concluded that ultra-short opiate detoxification carries the ris k of QT-prolongation and bradycardia. These side effects are reversible and can be explained by hypokalaemia and clonidine medication, the effects of which might reinforce each other. To avoid arrhythmic complications, ECG tr acings should be carried out regularly during recovery, i.e. at least daily , for a span of 3 days after discharge front the intensive care unit.