It has not previously been reported that sildenafil citrate causes malignant arrhythmias in humans.
A 41-year-old man developed sustained ventricular tachycardia following sildenafil citrate administration.
It cannot be dismissed that this patient experienced ventricular tachycardia as an adverse effect of sildenafil citrate administration.
Concerns about the safety of sildenafil citrate (Viagra├é┬«) have previously been raised 1. Other case reports and studies have described electrophysiological changes associated with ventricular arrhythmias following administration of sildenafil citrate 2-4.
We describe a case of a young man with no cardiac history or family history of heart disease or sudden death, developing sustained ventricular tachycardia after ingestion of sildenafil citrate. This case highlights a potential adverse effect of sildenafil citrate and the possible morbidity and potential lethality associated with this adverse effect.
In August, 2006, a 41-year-old man was transferred after an episode of sustained monomorphic ventricular tachycardia (VT). There was no history of any cardiopulmonary symptoms and no family history of heart disease or sudden death. The arrhythmia started after 90 minutes of moderate pace swimming. In the locker room the patient felt dizzy, had a feeling of tachycardia and experienced a brief, witnessed syncope. At admission to the referring hospital VT with a frequency of 220 min-1 was documented (figure 1). Blood pressure was 105/60 mmHg. Before transferral, the VT was treated with metoprolol 2 milligrams and amiodarone 300 milligrams intravenously and converted to sinus rhythm.
Figure 1. Sustained ventricular tachycardia in a 41-year-old man receiving sildenafil therapy. Original tracing when the patient was admitted to the hospital./>
Approximately 10 hours prior to the arrhythmia the patient had taken sildenafil citrate (Viagra├é┬«) 100 mg orally, which had been prescribed because of erectile dysfunction. He was not taking any other medication. Blood tests were unremarkable except for troponin T (0.82 mikrograms/Liter) and CKMB (40.8 mikrograms/Liter). Resting ECG, bicycle ergometer exercise testing, echocardiography with tissue Doppler imaging, coronary angiography and cardiac nuclear magnetic resonance scanning were all normal. Six endomyocardial biopsies from the right ventricle showed slight non-specific hypertrophy and slight interstitial fibrosis and no suspicion of arrhythmogenic right ventricle cardiomyopathy. An electrophysiological study using protocol stimulation in the apex and the outflow tract of the right ventricle induced 10 beats of non-sustained VT with alternating morphology. On a subsequent day, an additional electrophysiological study was conducted 41/2 hours following administration of 100 mg of Viagra├é┬« orally (serum concentration 0.36 mg/kg). On that occasion a non-sustained VT over 24 beats identical to the VT at admission was induced (figure 2). A prophylactic implantable cardioverter defibrillator (ICD) was implanted and the patient was instructed not to use sildenafil. At a follow-up visit in December 2006 interrogation of the ICD revealed that two events of VT had been detected and terminated by anti tachycardia pacing./>/>
- Food and Drug Administration: Postmarketing safety of sildenafil citrate (Viagra). Summary of reports of death in Viagra users received from marketing (late March) through mid-November 1998. [http://www.fda.gov/cder/consumerinfo/viagra/safety3.htm]
- Geelen P, Drolet B, Rail J, B─é┬®rub─é┬® J, Daleau P, Rousseau G, Cardinal R, O'Hara GE, Turgeon J: Sildenafil (Viagra) Prolongs Cardiac Repolarization by Blocking the Rapid Component of the Delayed Rectifier Potassium Current. Circulation 2000, 102:275-277.
- Ilson BE, Shaddinger BC, Dabiri GA, Patel BR, Boyle DA, Sethuraman V, Montague T, Morganroth J: A definitive study of the effects of PDE-5 inhibitors on cardiac repolarization in middle-age males. Journal of Clinical Pharmacology & Therapeutics 2004, 75:47.
- Swissa M, Ohara T, Lee MH, Kaul S, Shah PK, Hayashi H, Chen PS, Karagueuzian HS: Sildenafil-nitric oxide donor combination promotes ventricular tachyarrhythmias in the swine right ventricle. American Journal of Physiology-Heart and Circulatory Physiology 2002, 282(5):H1787-H1792.
- Goldstein I, Lue TF, Padma-Nathan H, Rosen RC, Steers WD, Wicker PA: Oral Sildenafil in the treatment of erectile dysfunction. New England Journal of Medicine 1998, 338:1397-1404.