Sinus node recovery time assessment by the overdrive suppression test employing an intravenous injection of disopyramide phosphate

Although sinus node recovery time (SNRT) assessment by the overdrive suppression test (ODST) is important in detecting sick sinus syndrome (SSS), its sensitivity is still inadequate. We have evaluated the effect of intravenous injection (i.v.) of disopyramide phosphate (DP) in ODST. The subjects were 30 SSS patients (64·910·0 years old). If SNRT was 525 ms) in 29 of the 30 patients (97%). In contrast, SNRT and CSNRT were shortened in the normal subjects during ODST after DP i.v. (P<0·01). The plasma concentration of DP estimated in nine patients was 4·11·0 g.m l 1 . No serious side effect occurred. ODST employing DP i.v. is safe and seems to be highly effective in diagnosing SSS. (Europace 2000; 2: 54–59)