Key result
Administration of sildenafil citrate did not alter corrected QT or QT variability indexes compared to the predrug phase.
Why the study?
Does 50 mg oral sildenafil citrate alter QT dynamicity properties compared to predrug baseline?
Does 50 mg oral sildenafil citrate alter QT dynamicity properties compared to predrug baseline?
A 50 mg dose of oral sildenafil citrate does not significantly alter QT dynamicity properties, suggesting that associated cardiac events are unlikely to be explained by ventricular arrhythmias.
Answers are grounded in this paper and cite their sources.
Sildenafil 50 mg does not alter QT dynamicity; supports arrhythmia-independent mechanisms for events but leaves open confirmation in randomized studies.
BACKGROUND: Sildenafil citrate may have direct cardiac electrophysiological effects, and is possibly responsible for some cardiac events. The aim of our study was to investigate the effects of sildenafil citrate on QT dynamicity properties with a new QT analysis program showing even small changes in ventricular repolarization. METHODS: Twenty-four-hour Holter electrocardiographic recordings were used to obtain the data in the predrug phase (1-hour rest position before drug administration), and in the postdrug phase (1-hour rest position, which began 60 minutes after 50 mg oral sildenafil citrate administration). With the special QT analysis program (Verda, Reynolds Medical Ltd., UK); mean values of RR, QT, QTo (corrected QT), J (the exponent of correction formula) and S (QT/RR plots slope) parameters together with QT variability indexes (QTVI) were calculated for study phases. RESULTS: Mean +/- SEM values for RR and QT were higher in postdrug phase than in predrug phase (RR: 845 +/- 42 ms vs 816 +/- 46 ms, P < 0.05; QT: 371 +/- 8 ms vs 361 +/- 9 ms, P < 0.05). However, sildenafil did not induce any significant change in mean +/- SEM values for QT(o), J, and S in postdrug phase compared with predrug phase (408 +/- 10 ms vs 406 +/- 8 ms, 0.474 +/- 0.030 vs 0.433 +/- 0.025, 0221 +/- 0.020 vs 0.198 +/- 0.017, respectively; P > 0.05). QTVIs were also not different in each phase (predrug: -0.874 +/- 0.071 vs postdrug: -0.997 +/- 0.067, P = 0.109). CONCLUSIONS: Fifty milligrams sildenafil does not affect QT dynamicity properties. The cardiac events associated with sildenafil could not be explained with ventricular arrhythmias.
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Kaya et al. (2004) studied this question. Sildenafil citrate vs. Predrug phase was evaluated on QT dynamicity properties including corrected QT (QTo) and QT variability indexes (QTVI) (p=>0.05). Administration of sildenafil citrate did not alter corrected QT or QT variability indexes compared to the predrug phase.
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