Objectives This randomizedstudy was designed to compare the safety and efficacy ofintravenous diltiazem versus intravenous cedilanid-D(deslanoside) for ventricular rate control in patientswith atrial fibrillation (AF). Analysis of the effect onconduction system of these drugs was also performed.Methods Forty three patients with AF were randomlyassigned to receive intravenous therapy with 0.25mg/kgdiltiazem (n = 21) or 0.4mg cedilanid-D (n = 22). Ifnot effective at 120 minutes (< 20% decrease inpretreatment ventricular rate or can not convert to sinusrhythm= another dose of diltiazem or 0.2mg cedilanid-Dwas administered. Blood pressure and electrocardio-graphic recordings were performed before and after 5,10, 20, 30, 60 minutes of drug administration. Furtherrecordings were performed at 120 minutes in non-effective patients, and at 180 minutes in patients whoreceived second time drug administration. To evaluatethe effect on conduction system of these two drugs bymeasuring PA, AH and HV intervals using His bundleelectrogram test another nineteen sinus rhythm patientswere randomized to diltiazem (n=9) and cedilanid (n=10) group. His bundle electrogram recordings wereperformed before and after 5, 10, 20 and 30 minutes ofdrug administration. Statistical significance was assessedwith the use of t test, Fisher’s exact test, ANOVA andLSD methodology. Results At baseline and after 5,10, 20, 30, 60 minutes of drug administration theheart rates (mean±SD) were(133+15), (92±20) , (87±22), (85±20), (85 ±21), (85±23)beats/minute indiltiazem group respectively and(140±21), (122±24),(118±25), (110±26), (112±25), (110±28) beats/minute in cedilanid-D group respectively. Heart ratereduction was higher in diltiazem group than cedilanidgroup during 5 (41±20 vs 17±14,P < 0 . 0 1 ) ; 1 0(46±21 vs 22±20, P<0.01); 20 (48±21 vs 29±22,P<0.01); 30(48±22 vs 27±22,P<0.01 )and 60 minutes(48±23 vs 29±24, P< 0.05). Both drugs had no effecton both systolic and diastolic blood pressure (P >0.05)and no major side effects were noticed. Diltiazemmaintained effective ventricular rate in 20 patients,whereas cedilanid-D maintained in 15 patients within180 minutes (95.2%vs 68.2%,P< 0.05). There wereno statistical significance in baseline heart rate, ageand weight between the two groups. Both diltiazem andcedilanid-D can increase AH interval, but have noeffect on HV and PA intervals in sinus rhythm patients.Conclusions Both diltiazem and cedilanid-Ddecrease ventricular heart rate, but heart rate reductionis significantly higher in diltiazem group, thus shouldbe considered as a drug of choice for emergency controlof ventricular rate. Under clinical monitoring this doseof diltiazem seems to be safe and applicable in AFpatients with congestive heart failure. Both drugs haveno effect on PA and HV intervals but increase the AHinterval thereby can reduce ventricular rate. Objectives This randomized study was designed to compare the safety and efficacy of intravenous diltiazem versus intravenous cedilanid-D (deslanoside) for ventricular rate control in patients with atrial fibrillation (AF). Analysis of the effect onconduction system of these drugs was also performed. Methods Forty three patients with AF were randomly assigned to receive intravenous therapy with 0.25 mg / kg diltiazem (n = 21) or 0.4 mg cedilanid-D (n = 22). Ifnot effective at 120 minutes (<20% decrease in pre- treatment ventricular rate or can not convert to sinusrhythm = Another dose of diltiazem or 0.2 mg cedilanid-Dwas administered. Blood pressure and electrocardio-graphic recordings were performed before and after 5, 10, 20, 30, 60 minutes of drug administration. Further recordings were performed at 120 minutes in non-effective patients, and at 180 minutes in patients whoreceived second time drug administration. To evaluate the effect on conduction system of these two drugs bymeasuring PA, AH and HV intervals using His bundleelectrogram test another nineteen sinus rhythm patientswere randomized to diltiazem (n = 9) and cedilanid (n = 10) group. His bundle electrogram recordings were performed before and after 5, 10, 20 and 30 minutes ofdrug administration. the use of t test, Fisher’s exact test, ANOVA and LSD methodology. Results At baseline and after 5,10, 20, 30, 60 minutes of drug administration the heart rates (mean ± SD) were (133 ± 15), (92 ± 20 (87 ± 22), (85 ± 20), (85 ± 21), (85 ± 23) beats / minute indiltiazem groups respectively and (140 ± 21), (122 ± 24), (118 ± 25) (110 ± 26), (112 ± 25), (110 ± 28) beats / minute in cedilanid-D groups respectively. Heart ratereduction was higher in diltiazem group than cedilanidgroup during 5 (41 ± 20 vs 17 ± 14, P <0 (48 ± 21 vs 29 ± 22, P <0.01); 30 (48 ± 22 vs 27 ± 22, P <0.01) and 60 minutes (48 ± 23 vs 29 ± 24, P <0.05). Both drugs had no effecton both systolic and diastolic blood pr essure (P> 0.05) and nomajor side effects were noticed. Diltiazemmaintained effective ventricular rate in 20 patients, cedilanid-D maintained in 15 patients within 180 minutes (95.2% vs 68.2%, P <0.05) There wereno statistical significance in baseline heart rate, ageand weightbetween the two groups. Both diltiazem and cedilanid-D can increase AH interval, but with noeffect on HV and PA intervals in sinus rhythm patients. Conclusions Both diltiazem and cedilanid-Ddecrease ventricular heart rate, but heart rate reductionis significantly higher in diltiazem group, thus should be considered as a drug of choice for emergency control of ventricular rate. Under clinical monitoring this dose of diltiazem seems to be safe and applicable in AFpatients with congestive heart failure. Both drugs haveno effect on PA and HV intervals but increase the AHinterval can can reduce ventricular rate.