Acute, symptomatic atrial fibrillation after sildenafil citrate therapy in a patient with hypertrophic obstructive cardiomyopathy

Combination of Sildenafil and Ba2+ at a Low Concentration Show a Significant Synergistic Inhibition of Inward Rectifier Potassium Current Resulting in Action Potential Prolongation

Sildenafil (Viagra) is a vasodilator mainly used in the treatment of erectile dysfunction. Atrial or ventricular fibrillation may rarely occur as a side effect during sildenafil therapy. Although changes in inward rectifier potassium currents including I_K1 are known to contribute to the pathogenesis of fibrillation, the effect of sildenafil on I_K1 has not been studied. In experiments, Ba²⁺ is used as a specific inhibitor of I_K1 at high concentrations (usually 100 µM). Being an environmental contaminant, it is also present in the human body; Ba²⁺ plasmatic concentrations up to 1.5 µM are usually reported in the general population. This study was primarily aimed to investigate changes of I_K1 induced by sildenafil in a wide range of concentrations (0.1–100 µM). Additionally, the effect of combination of sildenafil and Ba²⁺ at selected clinically-relevant concentrations was tested, at 0.1 µM both on I_K1 and on the action potential duration (APD). Experiments were performed by the whole-cell patch-clamp technique on enzymatically isolated rat ventricular cardiomyocytes, mostly at 23°C with the exception of APD measurements which were performed at 37°C as well. Sildenafil caused a significant, reversible, and concentration-dependent inhibition of I_K1 that did not differ at −50 and −110 mV. Simultaneous application of sildenafil and Ba²⁺ at 0.1 µM revealed a massive inhibition of both inward and outward components of I_K1 (this synergy was missing at other tested combinations). The combined effect at 0.1 µM (45.7 ± 5.7 and 43.0 ± 6.9% inhibition at −50 and −110 mV, respectively) was significantly higher than a simple sum of almost negligible effects of the individual substances and it led to a significant prolongation of APD at both 23 and 37°C. To our knowledge, similar potentiation of the drug-channel interaction has not been described. The observed massive inhibition of I_K1 induced by a combined action of the vasodilator sildenafil and environmental contaminant Ba²⁺ at a low concentration and resulting in a significant APD prolongation may contribute to the genesis of arrhythmias observed in some patients treated with sildenafil.

Drug-Induced Atrial Fibrillation / Atrial Flutter

Drug-induced atrial fibrillation / flutter (DIAF) is a serious and potentially life-threatening complication of pharmacotherapy. Purpose of the work: systematization and analysis of scientific literature data on drugs, the use of which can cause the development of DIAF, as well as on epidemiology, pathophysiological mechanisms, risk factors, clinical picture, diagnosis and differential diagnosis, treatment and prevention of DIAF. Analysis of the literature has shown that many groups of drugs can cause the development of DIAF, with a greater frequency while taking anticancer drugs, drugs for the treatment of the cardiovascular, bronchopulmonary and central nervous systems. The mechanisms and main risk factors for the development of DIAF have not been finally established and are known only for certain drugs, therefore, this section requires further study. The main symptoms of DIAF are due to the severity of tachycardia and their influence on the parameters of central hemodynamics. For diagnosis, it is necessary to conduct an electrocardiogram (ECG) and Holter monitoring of an ECG and echocardiography. Differential diagnosis should be made with AF, which may be caused by other causes, as well as other rhythm and conduction disturbances. Successful treatment of DIAF is based on the principle of rapid recognition and immediate discontinuation of drugs (if possible), the use of which potentially caused the development of adverse drug reactions (ADR). The choice of management strategy: heart rate control or rhythm control, as well as the method of achievement (medication or non-medication), depends on the specific clinical situation. For the prevention of DIAF, it is necessary to instruct patients about possible symptoms and recommend self-monitoring of the pulse. It is important for practitioners to be wary of the risk of DIAF due to the variety of drugs that can potentially cause this ADR.

Etiologies and Mechanisms of Ischemic Stroke Associated with Sexual Intercourse: A Literature Review

BACKGROUND

Exposure to some special events, also called stroke triggers, can precipitate the onset of ischemic stroke (IS). Previous studies have presented preliminary hypotheses about sexual intercourse as a trigger of IS in predisposed individuals, but the mechanisms of IS associated with sexual intercourse are still not well defined. This literature review summarizes the etiologies and mechanisms of IS associated with sexual intercourse. Further studies on stroke triggers are warranted, and early recognition and appropriate preventive strategies directed against the short-term risks posed by stroke triggers may complement the long-term risk factor reduction approach.

METHODS

Articles were selected from PubMed (1946-2021) and Web of Science Core Collection (1990-2021) using the following search terms: ischemic stroke, ischaemic stroke, stroke, cerebral infarction, cerebral ischemia, cerebral embolism, embolism, sexual intercourse, sexual activity, intercourse, coitus, coition, and coital.

RESULTS

A total of 20 studies, which included 26 patients with IS associated with sexual intercourse, were included. This literature review found that IS associated with sexual intercourse is not rare but has not received enough attention, and paradoxical embolization and postcoital arterial dissection are common etiologies. Other etiologies include drug usage (such as sexual adjuvant drugs and illicit drugs), paroxysmal sympathetic hyperactivity, and reversible cerebral vasoconstriction syndrome.

DISCUSSION/CONCLUSION

Sexual intercourse should be considered an important trigger for IS. Clinicians should be aware that IS associated with sexual intercourse is not subjective but may be a warning sign of multiple etiologies and mechanisms.

Erectile Dysfunction Is Not a Predictor of Atrial Fibrillation: A Population-Based Propensity-Score Matched Cohort Study

INTRODUCTION

Erectile dysfunction (ED) has been regarded a marker of cardiovascular diseases. Nevertheless, the association between ED and incident atrial fibrillation (AF) remains unknown.

AIM

To determine the association between ED and incident AF.

METHODS

This population-based cohort study was conducted using the National Health Insurance Research Database in Taiwan. In total, 6,273 of patients with ED without a prior diagnosis of AF were enrolled from January 1, 2001 through December 31, 2009, and a propensity-score matching method was used to identify 3,516 patients in the ED and control groups.

MAIN OUTCOME MEASURES

Newly incident AF at follow-up was recorded as the end point.

RESULTS

The mean age of the study population was 40.0 ± 17.1 years, and the follow-up period was 8.0 ± 0.5 years. Compared with the control group, patients with ED were older and had more of the following comorbidities: D'Hoore Charlson Comorbidity Index, hypertension, congestive heart failure, diabetes mellitus, dyslipidemia, chronic kidney disease, coronary artery disease, stroke, chronic lung disease, major depression disorder, obstructive sleep apnea, and hyperthyroidism. After adjusting for confounders, the ED group was not associated with more incident AF compared with the control group (hazard ratio = 1.031, 95% confidence interval = 0.674-1.578, P =.888). In these patients, ED of an organic origin was associated with a trend of having AF more often compared with ED of a psychosexual type (P =.272 by log-rank test).

CONCLUSION

Although ED is known as a predictor of atherosclerotic cardiovascular diseases, it is not independently associated with incident AF in men.

Ventricular fibrillation development following atrial fibrillation after the ingestion of sildenaphil in a patient with Wolff-Parkinson-White syndrome

Complications in the accessory pathway in Wolff-Parkinson-White (WPW) syndrome could cause different clinical conditions by inducing different arrhythmias. Atrial fibrillation (AF) is one of these arrhythmias and is important as it causes life-threatening arrhythmias. It is known that some drugs, underlying cardiac diseases, and the number of accessory pathways, cause a predisposition to this condition. In the current report, we presented a patient with WPW who was admitted to the emergency department with AF, wide QRS and a rapid ventricular response that progressed to ventricular fibrillation.

Drug-induced atrial fibrillation

INTRODUCTION

Atrial fibrillation (AF) is the most common arrhythmia and an important cause of hospitalization, morbidity, and mortality. A myriad of drugs can induce AF. However, drug-induced AF (DIAF) receives little attention. Thus, this review is an attempt to attract the attention on this adverse effect.

AREAS COVERED

Published reports of drug-induced AF (DIAF) are reviewed in this paper, from January 1974 to December 2011, using the PubMed/Medline database and lateral references.

EXPERT OPINION

In most cases, DIAF is paroxysmal and terminates spontaneously, but sometimes AF persists and it is necessary to perform a cardioversion to restore sinus rhythm and avoid progression to persistent AF. Because of the short duration of DIAF, in addition to physicians/patients not being knowledgeable about this side effect, the real incidence and clinical consequences of DIAF are presently unknown. DIAF is an increasing problem, as some widely prescribed drugs can present this adverse effect. The risk is expected to increase in the elderly and in patients with comorbidities. It is important that physicians understand the significance of DIAF, to increase the collaboration between cardiac and non-cardiac professionals, and to educate patients to make them aware of this adverse side effect.

Phosphodiesterase inhibitors, congestive heart failure, and sudden death: time for re-evaluation

A 42-year-old diabetic man was admitted with systolic heart failure and pulmonary hypertension being treated with sildenafil for the previous year. With an increase in creatinine, he experienced 3 episodes of ventricular tachycardia and ventricular fibrillation. Withdrawal of the phosphodiesterase (PDE) inhibitor resulted in no further episodes of dysrhythmias. The basic pharmacology of PDE inhibitors is presented and the use of PDE-3 inhibitors for the treatment of heart failure causing an increase in sudden death is also reviewed. There have been several cases of sudden death associated with sildenafil use and with its increasing use in patients with severe pulmonary hypertension and decompensated heart failure. The authors also reviewed the electrophysiologic effects of PDE-5 inhibitors associated with their use. The crossover between PDE-3 and PDE-5 inhibitors is also discussed and caution is urged when contemplating the use of PDE-5 inhibitors in patients with systolic heart failure and pulmonary hypertension.

Subarachnoid Hemorrhage and Intracerebral Hematoma due to Sildenafil Ingestion in a Young Adult

Sildenafil citrate (Viagra(R); Pfeizer US Pharmaceutical Group, New York, NY, USA) is a potent vasodilating agent to treat male erectile dysfunction. Among its adverse effects, hemorrhagic stroke has not been widely reported yet. We present a case of a 33-year-old healthy man who ingested 50 mg sildenafil a half hour before onset of headache, nervousness and speech disturbance. Head computed tomogram of this stuporous man showed huge intracerebral hemorrhage and thick subarachnoid hemorrhage, but angiography failed to disclose any vascular anomalies. Subsequent surgical procedure was followed, and rehabilitation was provided thereafter. Sildenafil seems to act by redistributing arterial blood flow, and concurrent sympathetic hyperactivity, which lead to such hemorrhagic presentation. Extreme caution should be paid on even in a young adult male patient wven without known risk factors.

The synergism of penile venous surgery and oral sildenafil in treating patients with erectile dysfunction

A possible synergistic effect between penile venous surgery and oral sildenafil was inadvertently found in treating patients with erectile dysfunction in our clinic. We therefore sought to elucidate the possible synergic effect between venous surgery and sildenafil through studying patients who were non-responders preoperatively. From July 1998 to July 2003, 128 patients were diagnosed with veno-occlusive dysfunction. Subsequently, 65 of them underwent penile venous surgery and were assigned to the surgical treatment group. The remaining 63 men were assigned to the control group, and were subject to a simple re-exposure of oral sildenafil. All patients were evaluated with the international index of erectile function (IIEF-5) scoring. Sildenafil (12.5-100 mg) was prescribed postoperatively to all surgical patients as venous surgery alone was unsatisfactory and similarly, 100 mg preparation was prescribed for patients in the control group. The IIEF-5 scoring in the control group changed from a preoperative mean IIEF-5 score of 9.4 +/- 3.9 to 10.7 +/- 3.5 postoperatively. In surgical patients, however, the mean preoperative IIEF-5 score of 9.2 +/- 5.0, which increased to 15.1 +/- 5.0 (p < 0.001) postoperatively, further increased to 20.1 +/- 5.4 (p < 0.0001) after the addition of sildenafil. Although there was no significant difference between the two groups characteristics, there was a statistically significant difference between treatment results (p < 0.001). Overall, 61 men (93.8%) reported a positive response to sildenafil after venous stripping surgery. In contrast, only eight patients (12.7%) felt a beneficial response in the control group (p < 0.001). Forty-one of 65 patients had scores of > or =22, and 19 of these had a score of 25. No response was found in three (4.6%), and a decrease of 7 was seen in one (1.5%). In summary, patients in whom sildenafil was not effective preoperatively can become excellent responders after careful penile venous surgery. It appears that together, oral sildenafil and penile venous surgery may provide an encouraging solution to impotent patients with veno-occlusive dysfunction who are non-responders to sildenafil.

Effects of combined treatment with sildenafil and itraconazole on the cardiovascular system in telemetered conscious dogs

Sildenafil, a potent PDE5 inhibitor, is widely prescribed as a treatment of erectile dysfunction. Itraconazole is an inhibitor of CYP3A4, a metabolic enzyme of sildenafil. In the current study, we investigated the effects of single treatment with sildenafil and combined treatment with sildenafil and itraconazole on blood pressure, heart rate, and QT interval in conscious beagle dogs. After a transmitter was implanted to beagle dogs for conscious state experiments, a single oral dose of sildenafil was administered to the beagle dogs at dose levels of 3, 15, and 30 mg/kg. Blood pressure, heart rate, and lead II ECG were measured prior to dosing and at 0.5, 1, 2, 4, 6, and 24 h postdosing. In the study of combined treatment with sildenafil and itraconazole, the 100 mg/kg dose of itraconazole was orally administered 1 h prior to oral administration of sildenafil. No changes in blood pressure were observed at any doses in animals receiving either single treatment with sildenafil or combined treatment with sildenafil and itraconazole. Increased heart rate from 0.5 h to 6 h postdosing and decreased QT interval were observed in animals receiving single treatment with sildenafil at 15 or 30 mg/kg. When 30 mg/kg of sildenafil was coadministered with 100 mg/kg of itraconazole, drug-related effects such as increased heart rate and decreased QT interval were significantly enhanced as compared to sildenafil-alone administration at 6 h postadministration. These results demonstrated that increased heart rate and decreased QT interval, the adverse effects of sildenafil, were enhanced and prolonged when sildenafil was coadministered with itraconazole. Therefore, caution should be taken when sildenafil is coadministered with itraconazole, a CYP3A4 inhibitor, or when administered to elderly patients or patients with hepatic or renal impairment who cannot metabolize and excrete sildenafil normally.