Key result
A 100-mg intravenous infusion of sildenafil citrate significantly increased the defibrillation threshold by approximately 19% by voltage (P<0.003) and 38% by total energy (P<0.01).
Why the study?
Does sildenafil citrate increase the defibrillation threshold during ventricular fibrillation in a pig model?
RCT (n=26)
Randomly assigned
Does sildenafil citrate increase the defibrillation threshold during ventricular fibrillation in a pig model?
Effect estimate: 19% increase by voltage, 38% by total energy
Absolute Event Rate: 483% vs 407%
p-value: p=<0.003
Supra-therapeutic doses of sildenafil citrate significantly increase the defibrillation threshold in a porcine model, suggesting higher shock strengths may be needed for successful defibrillation in patients on high-dose sildenafil.
May raise defibrillation energy needs in sildenafil-treated patients; leaves open translation to human VF.
INTRODUCTION: Although fatal arrhythmia and sudden death have been reported in patients taking sildenafil citrate, its effect on defibrillation efficacy has not been investigated. The aim of this study was to test the hypothesis that sildenafil citrate increases the shock strength required to successfully defibrillate during ventricular fibrillation (VF). METHODS AND RESULTS: A total of 26 pigs (20-25 kg) were randomly assigned into three groups. In each group, the defibrillation threshold (DFT) was determined at the beginning of the study using a three-reversal up/down protocol. Each shock (RV-SVC, biphasic) was delivered after 10 seconds of VF. Group 1 (n = 10) received 50 mg and group 2 (n = 10) received 100 mg of sildenafil citrate intravenously at a rate of 2 mL/minute for 50 minutes. Group 3 (n = 6) received 100 mL of saline intravenously at the same rate as in group 1. The DFT was determined again after the drug (drug-DFT) and saline (saline-DFT) administration. For 100-mg sildenafil citrate infusion, the DFT (483 +/- 39 V, 18 +/- 3 J) was significantly (P < 0.003 and P < 0.01, respectively) higher than the control-DFT (407 +/- 123 V, 13 +/- 7 J). This sildenafil citrate infusion increased the DFT approximately 19% by voltage, and approximately 38% by total energy. After 50-mg sildenafil citrate infusion, the DFT (454 +/- 28 V, 15 +/- 2 J) was not different than the control DFT (449 +/- 28 V, 15 +/- 2 J). Saline infusion (391 +/- 18 V, 12 +/- 1 J) did not alter the control DFT (399 +/- 22 V, 12 +/- 1 J). CONCLUSION: The 100-mg sildenafil citrate infusion, representing a supra-therapeutic plasma level, significantly increased the DFT. This finding indicates that VF occurring during supra-therapeutic sildenafil citrate treatment would require a stronger shock to successfully defibrillate.
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Shinlapawittayatorn et al. (2006) conducted an RCT in Ventricular fibrillation (n=26). Sildenafil citrate vs. Saline was evaluated on Defibrillation threshold (DFT) by voltage and total energy (19% increase by voltage, 38% by total energy, p=<0.003). A 100-mg intravenous infusion of sildenafil citrate significantly increased the defibrillation threshold by approximately 19% by voltage (P<0.003) and 38% by total energy (P<0.01).