Increased prevalence of prolonged QT interval in males with primary or secondary hypogonadism: a pilot study

Androgens and Androgen Receptors as Determinants of Vascular Sex Differences Across the Lifespan

Androgens, including testosterone and its more potent metabolite dihydrotestosterone, exert multiple actions in the body. Physiologically, they play a critical role in male sex development. In addition, they influence vascular function, including arterial vasodilation and mediation of myogenic tone. Androgens are produced from 9 weeks' gestation in the human fetal testis, as well as in small amounts by the adrenal glands. Serum concentrations vary according to age and sex. The vasculature is a target for direct actions of androgens, which bind to various sex hormone receptors expressed in endothelial and vascular smooth muscle cells. Androgens exert both vasoprotective and vasoinjurious effects, depending on multiple factors including sex-specific effects of androgens, heterogeneity of the vascular endothelium, differential expression of androgen and sex hormone receptors in endothelial and vascular smooth muscle cells, and the chronicity of androgen administration. Long-term administration of androgens induces vasoconstriction and influences endothelial permeability, whereas acute administration may have opposite effects. At the cellular level, androgens stimulate endothelial cell production of nitric oxide and inhibit proinflammatory signalling pathways, inducing vasorelaxation and vasoprotection. However, androgens also activate endothelial production of vasoconstrictors and stimulate recruitment of endothelial progenitor cells. In humans, both androgen deficiency and androgen excess are associated with increased cardiovascular morbidity and mortality. This review discusses how androgens modulate vascular sex differences across the lifespan by considering the actions and production of androgens in both sexes and describes how cardiovascular risk is altered as levels of androgens change with aging.

Vascular dysfunction and increased cardiovascular risk in hypospadias

AIMS

Hypogonadism is associated with cardiovascular disease. However, the cardiovascular impact of hypogonadism during development is unknown. Using hypospadias as a surrogate of hypogonadism, we investigated whether hypospadias is associated with vascular dysfunction and is a risk factor for cardiovascular disease.

METHODS AND RESULTS

Our human study spanned molecular mechanistic to epidemiological investigations. Clinical vascular phenotyping was performed in adolescents with hypospadias and controls. Small subcutaneous arteries from penile skin from boys undergoing hypospadias repair and controls were isolated and functional studies were assessed by myography. Vascular smooth muscle cells were used to assess: Rho kinase, reactive oxygen species (ROS), nitric oxide synthase/nitric oxide, and DNA damage. Systemic oxidative stress was assessed in plasma and urine. Hospital episode data compared men with a history of hypospadias vs. controls. In adolescents with hypospadias, systolic blood pressure (P = 0.005), pulse pressure (P = 0.03), and carotid intima-media thickness standard deviation scores (P = 0.01) were increased. Arteries from boys with hypospadias demonstrated increased U46619-induced vasoconstriction (P = 0.009) and reduced acetylcholine-induced endothelium-dependent (P < 0.0001) and sodium nitroprusside-induced endothelium-independent vasorelaxation (P < 0.0001). Men born with hypospadias were at increased risk of arrhythmia [odds ratio (OR) 2.8, 95% confidence interval (CI) 1.4-5.6, P = 0.003]; hypertension (OR 4.2, 95% CI 1.5-11.9, P = 0.04); and heart failure (OR 1.9, 95% CI 1.7-114.3, P = 0.02).

CONCLUSION

Hypospadias is associated with vascular dysfunction and predisposes to hypertension and cardiovascular disease in adulthood. Underlying mechanisms involve perturbed Rho kinase- and Nox5/ROS-dependent signalling. Our novel findings delineate molecular mechanisms of vascular injury in hypogonadism, and identify hypospadias as a cardiovascular risk factor in males.

Androgen Deprivation Therapy, Hypogonadism and Cardiovascular Toxicity in Men with Advanced Prostate Cancer

Androgen deprivation therapy (ADT) is successfully used in patients with advanced prostatic cancer, but there are many concerns about its systemic side effects, especially due to advanced age and frequent comorbidities in most patients. In patients treated with ADT there are metabolic changes involving the glycaemic control and lipid metabolism, increased thrombotic risk, an increased risk of myocardial infarction, severe arrhythmia and sudden cardiac death. Still, these adverse effects can be also due to the subsequent hypogonadism. Men with heart failure or coronary artery disease have a lower level of serum testosterone than normal men of the same age, and hypogonadism is related to higher cardiovascular mortality. Many clinical studies compared the cardiovascular effects of hypogonadism post orchiectomy or radiotherapy with those of ADT but their results are controversial. However, current data suggest that more intensive treatment of cardiovascular risk factors and closer cardiological follow-up of older patients under ADT might be beneficial. Our paper is a narrative review of the literature data in this field.

Cardiovascular risk and testosterone - from subclinical atherosclerosis to lipoprotein function to heart failure

The cardiovascular (CV) benefit and safety of treating low testosterone conditions is a matter of debate. Although testosterone deficiency has been linked to a rise in major adverse CV events, most of the studies on testosterone replacement therapy were not designed to assess CV risk and thus excluded men with advanced heart failure or recent history of myocardial infarction or stroke. Besides considering observational, interventional and prospective studies, this review article evaluates the impact of testosterone on atherosclerosis process, including lipoprotein functionality, progression of carotid intima media thickness, inflammation, coagulation and thromboembolism, quantification of plaque volume and vascular calcification. Until adequately powered studies evaluating testosterone effects in hypogonadal men at increased CV risk are available (TRAVERSE trial), clinicians should ponder the use of testosterone in men with atherosclerotic cardiovascular disease and discuss benefit and harms with the patients.

The Impact of Testosterone on the QT Interval: A Systematic Review

Humans and mammals have sex-specific differences in cardiac electrophysiology, linked to the action of sex hormones in the cardiac muscle. These hormones can upregulate or downregulate the expression of ionic channels modulating the cardiac cycle through genomic and non-genomic interactions. Systematic search in PubMed, Medline and EMBASE including keywords pertaining to testosterone and QT interval. Included experimental studies and observation studies and case reports presenting the results of testosterone administration, excess or deficiency in humans and animals. Testosterone has been shown to shorten the action potential duration, by enhancing the expression of K⁺ channels and downregulating I_CaL increasing the repolarization reserve of the cardiac muscle. This effect has been observed in both genders and animals. Testosterone deficient states can promote arrhythmogenesis. The evidence in this paper may be used to guide clinical considerations, such as increased clinical surveillance of patients in testosterone deficient states using ECG.

Evolution of Electrocardiographic Repolarization Parameters During Antiandrogen Therapy in Patients with Prostate Cancer and Hypogonadism

We assessed the effects of antiandrogen therapy on ECG parameters of ventricular repolarization related to arrhythmic risk in 35 patients aged 70.3 ± 7 years with advanced prostate cancer treated with degarelix associated with enzalutamide (group A, 26 patients) or degarelix monotherapy (group B, 9 patients). We analyzed Fridericia corrected Q-T interval (QTc), Q-T dispersion (QTd), J-Tpeak interval (JTp), mean and maximum Tpeak-Tend interval (Tpe) and Tpe/QT ratio, Tpeak-Tend dispersion (Tped), index of cardio-electrophysiological balance (iCEB) from ECG tracings, and occurrence of ventricular premature beats (VPB) recorded by Holter ECG, before initiation of medication (M0) and after 6 months of treatment (M1). The groups had similar demographics except for a higher prevalence of prior myocardial infarction in group B (p = 0.01). All patients had low serum testosterone at M1. Baseline QTc, QTd, maxTpe/QT, meanTpe, maxTpe, Tped values were higher in B compared to A. They had a significant prolongation at M1 only in A. 20 patients in A and 6 in B had a 10% prolongation or decrease of iCEB (p = 0.66). In 5 patients, VPB severity increased from non-complex to complex: 3 in A and 2 in B (p = 0.31), but no sustained ventricular arrhythmia was registered. In conclusion, after 6 months of treatment, patients with hypogonadism on degarelix associated with enzalutamide had significant prolongation of QTc, QTd, maxTpe, meanTpe/QT, maxTpe/QT, Tped compared to patients on degarelix alone. The proportion of patients with 10% iCEB variation was similar between groups. There was no record of severe arrhythmias during the first 6 months of treatment.

Preserving Well-being in Patients With Advanced and Late Prostate Cancer

Androgen deprivation therapy, alone or in combination with androgen signaling inhibitors, is a treatment option for patients with advanced prostate cancer (PC). When making treatment decisions, health care providers must consider the long-term effects of treatment on the patient's overall health and well-being. Herein, we review the effects of these treatments on the musculoskeletal and cardiovascular systems, cognition, and fall risk, and provide management approaches for each. We also include an algorithm to help health care providers implement best clinical practices and interdisciplinary care for preserving the overall well-being of PC patients.

Late-onset hypogonadism: Reductio ad absurdum of the cardiovascular risk-benefit of testosterone replacement therapy

BACKGROUND

Low testosterone (T) level is considered a marker of poor cardiovascular health. Ten years ago, the Testosterone in Older Men with Mobility Limitations (TOM) trial was discontinued due to a higher number of adverse events in men receiving T compared with placebo. Since then, several studies have investigated the risks of T replacement therapy (TRT) in late-onset hypogonadism (LOH).

OBJECTIVE

To review the mechanism by which TRT could damage the cardiovascular system.

MATERIALS AND METHODS

Comprehensive literature search of recent clinical and experimental studies.

RESULTS

The mechanisms of T-mediated coronary vasodilation were reviewed with emphasis on calcium-activated and ATP-sensitive potassium ion channels. We showed how T regulates endothelial nitric oxide synthase (eNOS) and phosphoinositide 3-kinase/protein kinase B/eNOS signaling pathways in vessel walls and its direct effects on cardiomyocytes via β1-adrenergic and ryanodine receptors and provided data on myocardial infarction and heart failure. Vascular smooth muscle senescence could be explained by the modulation of growth factors, matrix metalloproteinase-2, and angiotensin II by T. Furthermore, leukocyte trafficking, facilitated by changes in TNF-α, could explain some of the effects of T on atheromatous plaques. Conflicting data on prothrombotic risk linked to platelet aggregation inhibition via NO-triggered arachidonate synthesis or increased aggregability due to enhanced thromboxane A in human platelets provide evidence regarding the hypotheses on plaque maturation and rupture risk. The effects of T on cardiac electrophysiology and oxygen delivery were also reviewed.

DISCUSSION

The effects of TRT on the cardiovascular system are complex. Although molecular studies suggest a potential benefit, several clinical observations reveal neutral or occasionally detrimental effects, mostly due to confounding factors.

CONCLUSIONS

Attempts to demonstrate that TRT damages the cardiovascular system via systematic analysis of the putative mechanisms led to the contradiction of the initial hypothesis. Current evidence indicates that TRT is safe once other comorbidities are addressed.

Cardiac arrhythmia considerations of hormone cancer therapies

Breast and prostate cancers are among the most prevalent cancers worldwide. Oestradiol and progesterone are major drivers for breast cancer proliferation, and androgens for prostate cancer. Endocrine therapies are drugs that interfere with hormone-activated pathways to slow cancer progression. Multiple new breakthrough drugs improving overall survival have recently been developed within this class. As the use of these latter drugs grows, incidence of cardiac arrhythmias has emerged as an unappreciated complication. These changes are not surprising given that sex hormones alter ventricular repolarization. Testosterone shortens action potential duration and QT interval duration, while oestradiol has an opposite effect. In patients with breast cancer, selective oestrogen receptor modulators are associated with more reports for long QT and torsade de pointes (TdP) than aromatase inhibitors, likely through an oestradiol-like effect on the heart. Cyclin-dependent kinase 4/6 inhibitors, a new class of anticancer drugs used in combination with endocrine therapies in hormone receptor positive breast cancer, are also variably associated with drug-induced long QT, particularly with ribociclib. In prostate cancer, androgen deprivation therapy is associated with long QT and TdP, and possibly atrial fibrillation for abiraterone. In this review, we have summarized the clinical and preclinical data focusing on cardiac arrhythmia considerations of hormone cancer therapies.

Changes in left ventricular repolarization after short-term testosterone replacement therapy in hypogonadal males

BACKGROUND AND AIM

Evidences suggest that androgen deficiency is associated with sudden cardiac death (SCD). Our purpose was to analyse some electrocardiographic (ECG) markers of repolarization phase in hypogonadal patients either at baseline or after testosterone replacement therapy (TRT).

PATIENTS AND METHODS

Baseline and after 6 months of testosterone replacement therapy, 14 hypogonadal patients and 10 age-matched controls underwent a short-term ECG recordings at rest and immediately after a maximal exercise test. The following ECG parameters have been collected: QTe (the interval between the q wave the end of T wave), QTp (the interval between the q wave and the peak of T wave), and Te (the interval between the peak and the end of T wave).

RESULTS

At baseline, in the hypogonadal patients, corrected QTe and QTp values were longer at rest than in the controls at rest (p < 0.05), whereas, during the recovery phase, only the QTp remained significantly longer (p < 0.05). After TRT, hypogonadal patients showed an improvement only in Te (p < 0.05). Conversely, any difference between hypogonadal patients and control subjects was found with respect to the markers of temporal dispersion of repolarization phases, except for a worse QTp → Te coherence (p = 0.001) obtained during the recovery phase.

CONCLUSIONS

In conclusion, at rest, hypogonadal patients suffer from a stable increase in the myocardial repolarization phase without an increase in its temporal dispersion and, hence, the SCD risk seems to be low.

Randomized controlled trials - mechanistic studies of testosterone and the cardiovascular system

Testosterone deficiency is common in men with cardiovascular disease (CVD), and randomized placebo-controlled trials (RCTs) have reported beneficial effects of testosterone therapy on exercise-induced cardiac ischemia in chronic stable angina, functional exercise capacity, maximum oxygen consumption during exercise (VO_2max) and muscle strength in chronic heart failure (CHF), shortening of the Q-T interval, and improvement of some cardiovascular risk factors. Testosterone deficiency is associated with an adverse CV risk profile and mortality. Clinical and scientific studies have provided mechanistic evidence to support and explain the findings of the RCTs. Testosterone is a rapid-onset arterial vasodilator within the coronary circulation and other vascular beds including the pulmonary vasculature and can reduce the overall peripheral systemic vascular resistance. Evidence has demonstrated that testosterone mediates this effect on vascular reactivity through calcium channel blockade (L-calcium channel) and stimulates potassium channel opening by direct nongenomic mechanisms. Testosterone also stimulates repolarization of cardiac myocytes by stimulating the ultra-rapid potassium channel-operated current. Testosterone improves cardiac output, functional exercise capacity, VO_2max and vagally mediated arterial baroreceptor cardiac reflex sensitivity in CHF, and other mechanisms. Independent of the benefit of testosterone on cardiac function, testosterone substitution may also increase skeletal muscle glucose metabolism and enhance muscular strength, both factors that could contribute to the improvement in functional exercise capacity may include improved glucose metabolism and muscle strength. Testosterone improves metabolic CV risk factors including body composition, insulin resistance, and hypercholesterolemia by improving both glucose utilization and lipid metabolism by a combination of genomic and nongenomic actions of glucose uptake and utilization expression of the insulin receptor, glucose transporters, and expression on regulatory enzymes of key metabolic pathways. The effect on high-density lipoprotein-cholesterol (HDL-C) differs between studies in that it has been found to fall, rise, or have no change in levels. Testosterone replacement can suppress the levels of circulating pro-inflammatory cytokines and stimulate the production of interleukin-10 (IL-10) which has anti-inflammatory and anti-atherogenic actions in men with CVD. No effect on C-reactive protein has been detected. No adverse effects on clotting factors have been detected. RCTs have not clearly demonstrated any significant evidence that testosterone improves or adversely affects the surrogate markers of atherosclerosis such as reduction in carotid intima thickness or coronary calcium deposition. Any effect of testosterone on prevention or amelioration of atherosclerosis is likely to occur over years as shown in statin therapy trials and not months as used in testosterone RCTs. The weight of evidence from long-term epidemiological studies supports a protective effect as evidenced by a reduction in major adverse CV events (MACEs) and mortality in studies which have treated men with testosterone deficiency. No RCT where testosterone has been replaced to the normal healthy range has reported a significant benefit or adverse effect on MACE nor has any recent meta-analysis.

Testosterone, myocardial function, and mortality

The cardiovascular system is particularly sensitive to androgens, but some controversies exist regarding the effect of testosterone on the heart. While among anabolic abusers, cases of sudden cardiac death have been described, recently it was reported that low serum level of testosterone was correlated with increased risk of cardiovascular diseases (CVD) and mortality rate. This review aims to evaluate the effect of testosterone on myocardial tissue function, coronary artery disease (CAD), and death. Low testosterone level is associated with increased incidence of CAD and mortality. Testosterone administration in hypogonadal elderly men and women has a positive effect on cardiovascular function and improved clinical outcomes and survival time. Although at supraphysiologic doses, androgen may have a toxic effect, and at physiological levels, testosterone is safe and exerts a beneficial effect on myocardial function including mechanisms at cellular and mitochondrial level. The interaction with free testosterone and estradiol should be considered. Further studies are necessary to better understand the interaction mechanisms for an optimal androgen therapy in CVD.

Testosterone Replacement Therapy in Deficient Patients With Chronic Heart Failure: A Randomized Double-Blind Controlled Pilot Study

BACKGROUND

Testosterone deficiency is associated with heart failure (HF) progression and poor prognosis. Testosterone therapy has been shown to improve exercise capacity in patients with chronic HF, but no trial has evaluated the impact of replacement in patients with demonstrated testosterone deficiency.

METHODS

Prospective, randomized, double-blind, placebo-controlled, and parallel-group trial comparing testosterone replacement with placebo in males with chronic HF with reduced ejection fraction (HFrEF) and testosterone deficiency (NCT01813201). Long-acting undecanoate testosterone at a fixed dose of 1000 mg was supplied by intramuscular injection at inclusion and then every 3 months. The placebo group received isotonic saline serum. Patients were randomly allocated 1:1 to testosterone or placebo while receiving optimal medical therapy, and the study was conducted for 12 months.

RESULTS

The final sample comprised 29 patients, 15 in the placebo group and 14 in the testosterone group (aged 65 ± 8, 62% with an ischemic etiology, left ventricular ejection fraction [LVEF] 30% ± 6%, 69% New York Heart Association functional [NYHA II]). After 12 months, testosterone replacement increased testosterone levels ( P = .002) but was not associated with benefit in terms of clinical symptoms and functional capacity including NYHA class, Framingham score, Minnesota Living Heart Failure Questionnaire, 6-minute walk test, or LVEF and N-terminal pro-B-type natriuretic peptide levels. No significant side effects associated with testosterone treatment were observed. No effects were found in other hormonal, metabolic, and bone turnover biomarkers.

CONCLUSION

In patients with HFrEF and testosterone deficiency, replacement therapy was not associated with any significant improvement.

Effect of Degarelix, a Gonadotropin-Releasing Hormone Receptor Antagonist for the Treatment of Prostate Cancer, on Cardiac Repolarisation in a Randomised, Placebo and Active Comparator Controlled Thorough QT/QTc Trial in Healthy Men

BACKGROUND AND OBJECTIVES

Degarelix is a gonadotropin-releasing hormone antagonist registered for the treatment of advanced hormone-dependent prostate cancer. Treatment causing androgen deprivation is associated with QT prolongation and this study investigated whether degarelix at supratherapeutic concentrations has an intrinsic effect per se on cardiac repolarisation and the QT interval.

METHODS

This was a single-centre, randomised, crossover study comparing the effect of degarelix, placebo, and the positive control moxifloxacin on the QT interval. Degarelix and placebo treatments were double-blind, whereas moxifloxacin treatment was open-label. Eighty healthy men, aged 18-45 years, received single intravenous doses of degarelix 2.8 mg, and placebo, as well as a single oral dose of moxifloxacin 400 mg. Electrocardiograms were collected up to 24 h after the start of administration, with the QT interval assessed and plasma concentrations of degarelix concomitantly analysed.

RESULTS

Time-matched, one-sided 95% upper confidence boundaries for baseline-corrected average changes from placebo for the QT interval, corrected using the Fridericia method (ΔΔQTcF), did not exceed 10 ms at any timepoint, with maximum degarelix concentrations reaching approximately threefold the concentrations seen in the treatment of prostate cancer. Furthermore, concentration-exposure analysis indicated absence of any QT prolongation effects of degarelix. No significant effect on any other cardiac parameter was observed. The lower bound of the 98.3% confidence interval for moxifloxacin ΔΔQTcF exceeded 5 ms, thus verifying assay sensitivity.

CONCLUSION

The results showed that the study was validated to detect a significant effect on the QT interval, and that degarelix by itself does not have any effect on the QT interval and cardiac repolarisation at supratherapeutic concentrations.

Aromatase knockout mice reveal an impact of estrogen on drug-induced alternation of murine electrocardiography parameters

Our in vitro characterization showed that physiological concentrations of estrogen partially suppressed the I(Kr) channel current in guinea pig ventricular myocytes and the human ether-a-go-go-related gene (hERG) channel currents in CHO-K1 cells regardless of estrogen receptor signaling and revealed that the partially suppressed hERG currents enhanced the sensitivity to the hERG blocker E-4031. To obtain in vivo proof-of-concept data to support the effects of estrogen on cardiac electrophysiology, we here employed an aromatase knockout mouse as an in vivo estrogen-null model and compared the acute effects of E-4031 on cardiac electrophysiological parameters with those in wild-type mice (C57/BL6J) by recording surface electrocardiogram (ECG). The ablation of circulating estrogens blunted the effects of E-4031 on heart rate and QT interval in mice under a denervation condition. Our result provides in vivo proof of principle and demonstrates that endogenous estrogens increase the sensitivity of E-4031 to cardiac electrophysiology.

No Untoward Effect of Long-Term Ketoconazole Administration on Electrocardiographic QT Interval in Patients with Cushing's Disease

Ketoconazole is listed among drugs that prolong QT interval and may increase the risk of torsade de pointes, a severe ventricular arrhythmia. This compound has recently been approved for treatment of Cushing's syndrome, a severe endocrine disorder. These patients harbour several risk factors for prolonged QT interval, for example hypokalaemia and left ventricular hypertrophy, but no study has evaluated whether administration of ketoconazole affects their QT interval. The aim of this study was to assess the QT interval in patients with Cushing's disease during long-term administration of ketoconazole. Electrocardiograms from 15 patients with Cushing's disease (12 women, 3 men, age: 37.8 ± 2.66 years) on ketoconazole treatment (100 mg-800 mg qd) for 1 month to 12 years were reviewed retrospectively. QT interval was measured and corrected for heart rate (QTc). Measurements before and during ketoconazole treatment were compared and any abnormal QTc value recorded. Concurrent medical therapies were also documented. On average, QTc was superimposable before and during ketoconazole treatment (393.2 ± 7.17 versus 403.3 ± 6.05 msec. in women; 424.3 ± 23.54 versus 398.0 ± 14.93 msec. in men, N.S.). QTc normalized on ketoconazole in one man with prolonged QTc prior to treatment; no abnormal QTc was observed in any other patient during the entire observation period, even during concurrent treatment with other QT-prolonging drugs. In conclusion, long-term ketoconazole administration does not appear to be associated with significant prolongation of QT interval in patients with Cushing's disease. ECG monitoring can follow recommendations drawn for other low-risk QT-prolonging drugs with attention to specific risk factors, for example hypokalaemia and drug interactions.

Effect of testosterone replacement therapy on cardiac performance and oxidative stress in orchidectomized rats

AIM

To investigate the effects of testosterone on myocardial contractility, oxidative stress status and expression of sodium channel protein (Nav1.5) and inward rectifying K channels (Kir 2.x) in normal and orchidectomized (ORX) rats.

METHODS

One hundred four rats were randomly assigned into four groups (n = 26, each) as follows: (i) untreated controls, (ii) testosterone treated, (iii) orchidectomized rats and (iv) orchidectomized, testosterone-treated rats. Treatments with the vehicle or testosterone were carried out for 12 weeks, three times per week. At the end of treatment, surface ECG, isolated heart, tissue oxidative stress and lipid peroxidation experiments were carried out on the cardiac tissues. Also, immunohistochemical examination for Nav1.5 and PCR detection of mRNA of Kir2.1, Kir2.2 and Kir2.4 subunits of K channels were carried out.

RESULTS

Orchidectomy impaired cardiac contractile function parameters left ventricular developed pressure (LVDP) and the peaks of the positive and negative pressure derivatives (dP/dtmax and -dP/dtmax respectively), increased heart rate and prolonged QT and QTc intervals, elevated pro-oxidant state in rat's hearts and decreased the expression of Kir 2.1 but not Kir2.2, Kir 2.4 and Nav1.5 channels. Exogenous testosterone administration to orchidectomized rats restored heart contractility and shortened QT and QTc intervals to their normal values, ameliorated the generated pro-oxidant state and improved the expression of Nav1.5 and Kir2.1, but not Kir2.2 or Kir2.4 channels.

CONCLUSION

Testosterone improved cardiac contractility and shortened QT and QTc intervals in ORX rats. An effect that might be dependent of reduction in oxidative stress and enhancement of Kir2.1 channels but independent of Nav1.5 channel protein.

Testosterone replacement therapy improves QTaVI in hypogonadal men with spinal cord injury

AIM

To determine the effect of a 12-month intent-to-treat testosterone (T) replacement therapy (TRT) trial on QTa interval variability (QTaVI) in hypogonadal (HG) men with spinal cord injury (SCI).

METHOD

A prospective, controlled 12-month TRT trial was completed in 22 healthy, chronic, nonambulatory men with SCI. Based on serum T concentration, subjects were designated as HG (≤ 11.3 nmol/l) or eugonadal (EG ≥ 11.4 nmol/l). Digital 3-lead electrocardiograms were performed. Heart rate (RR), heart rate variability [including total power (TPRR), low frequency (LFRR) and high frequency (HFRR)], QTa, QTe, and RT intervals, QTC (Bazett formula), QTVN, and QTaVI were calculated and evaluated at baseline and at 12 months. Lipoprotein profiles (triglycerides, total cholesterol, low-density and high-density lipoproteins) were obtained at the respective time points.

RESULTS

Based on serum T concentration, 13 subjects were designated as HG and 11 as EG. During the trial, there were no group differences for RR, QTa, QTe or RT intervals, QTC, TPRR, HFRR, or lipoproteins. The HG group was older (p < 0.05) and their LFRR was lower (p < 0.05) at baseline. At baseline, QTaVI was significantly greater in the HG group compared to the EG group [-0.17 (0.92) vs. -1.07 (0.90); p < 0.05]. After TRT, this group difference was no longer present [-0.44 (0.87) vs. -0.65 (0.85)] and the change in the HG group was significant (p < 0.05).

CONCLUSION

Hypogonadism in men with SCI was associated with elevated QTaVI at baseline. After 12 months of physiological TRT, the QTaVI improved in association with raising T into the normal range. These findings occurred independently of the prolongation of the QT interval.

Sex hormones and the QT interval: a review

A prolonged QT interval is a marker for an increased risk of ventricular tachyarrhythmias. Both endogenous and exogenous sex hormones have been shown to affect the QT interval. Endogenous testosterone and progesterone shorten the action potential, and estrogen lengthens the QT interval. During a single menstrual cycle, progesterone levels, but not estrogen levels, have the dominant effect on ventricular repolarization in women. Studies of menopausal hormone therapy (MHT) in the form of estrogen-alone therapy (ET) and estrogen plus progesterone therapy (EPT) have suggested a counterbalancing effect of exogenous estrogen and progesterone on the QT. Specifically, ET lengthens the QT, whereas EPT has no effect. To date, there are no studies on oral contraception (OC) and the QT interval, and future research is needed. This review outlines the current literature on sex hormones and QT interval, including the endogenous effects of estrogen, progesterone, and testosterone and the exogenous effects of estrogen and progesterone therapy in the forms of MHT and hormone contraception. Further, we review the potential mechanisms and pathophysiology of sex hormones on the QT interval.

High prevalence of prolonged QT interval in obese hypogonadal males

Obese subjects show several electrocardiographic alterations, including prolonged QT interval, a marker for fatal cardiac arrhythmias. Prolonged QT interval has recently been linked to low testosterone levels, a frequent occurrence in male obese patients but no study has yet assessed whether hypoandrogenism contributes to QT interval prolongation in this population. Aim of this study was to evaluate whether prolonged QT interval is linked to hypogonadism in male obese subjects. QT interval corrected for heart rate (QTc) was measured from standard electrocardiogram recordings in 136 obese men (BMI 30 >kg/m(2), range 30.1-75.4 kg/m(2)). Obese men were classified as eugonadal or hypogonadal according to serum total testosterone levels (i.e., greater or less than 9.9 nmol/l). Our study showed that QTc measurements corrected by either Bazett (419 ± 3.2 vs. 408 ± 3.4 ms, P < 0.05), Fridericia (406.3 ± 3.39 vs. 396.4 ± 3.03 ms, P < 0.05) or Hodges (407.0 ± 3.12 vs. 397.3 ± 2.84 ms, P < 0.05) were longer in hypogonadal compared with eugonadal obese men; further, prolonged QTc interval (i.e., >440 ms) was more frequent among hypogonadal compared with eugonadal obese men (23% vs. 10%, P < 0.05). The degree of weight excess, diabetes, sleep apnoea and potassium levels were not associated with prolonged QTc. In conclusion, obese hypogonadal men show a greater prevalence of prolonged QT interval compared with their eugonadal counterparts. It appears therefore that low levels of testosterone in obese men may contribute to the arrhythmogenic profile of these patients, a heretofore unknown link which warrants further clinical attention.

Male hormonal contraception: potential risks and benefits

An effective, safe, reversible, and acceptable method of contraception is an important component of reproductive health and provides the opportunity of shared responsibility for family planning for both partners. Female hormonal contraceptives have been proven to be safe, reversible, available and widely acceptable by different populations. In contrast, male hormonal contraception, despite significant progress showing contraceptive efficacy comparable to female hormonal methods during last three decades, has not yet led to an approved product. Safety of a pharmaceutical product is an appropriate concern but the majority of male hormonal contraceptive clinical trials have not reported significant short term safety concerns. While the absence of serious adverse effects is encouraging, the studies have been designed for efficacy endpoints not long term safety. In this review we summarize potential risks and benefits of putative male hormonal contraceptives on reproductive and non-reproductive organs. While the review covers what we believe will be the likely class of drugs used for male hormonal contraception a true assessment of long term risks and benefits cannot be achieved without an available product.

Testosterone replacement therapy and cardiovascular risk factors modification

Hypogonadism in males is associated with increased atherosclerotic disease. Physiologically, testosterone appears to have both positive and negative effects on the cardiovascular system. Testosterone decreases angina and may improve the cardiac healing response after myocardial infarction. Testosterone enhances function in males with heart failure (HF). Testosterone causes water retention and oedema is common in older persons. Oedema should not be used to diagnose HF in older persons. Studies in older persons with HF and frailty have shown a non-statistically lower mortality rate compared to those receiving placebo.

Effects of testosterone on the Q-T interval in older men and older women with chronic heart failure

The Q-Tc interval duration on the electrocardiogram is recognized to differ between the sexes. In vitro data and data from humans before and after puberty and menopause suggest that sex hormones play a role in the longer Q-Tc intervals in women, or conversely, the shorter Q-Tc intervals in men. Direct investigations of sex hormone effects on the Q-Tc interval in humans, however, are limited and reach conflicting conclusions. Our objective was to determine effects of testosterone on ECG Q-T intervals of older men and older women. ECG's from 84 older men and older women in double-blind placebo-controlled investigations of testosterone supplementation for the treatment of chronic heart failure (CHF) were analysed. Thirty men received 1000mg intramuscular long-acting testosterone undecanoate and 28 men received saline at 0, 6 and 12weeks. ECG's were recorded at baseline and 12weeks. Sixteen women received transdermal testosterone (33μg) and 10 women received matching placebo twice weekly for 24 weeks with ECG's at baseline and after 24weeks. Testosterone, but not placebo, shortened Q-T and Q-Tc intervals without heart rate changes. Q-T intervals decreased from 385±28 (mean±SD) to 382±28 ms (p<0.002) and Q-Tc intervals decreased from 398±26 to 392±27 (p<0.006) in men on testosterone. In women, Q-T intervals decreased from 400±25 to 397±23ms (p=0.06) and Q-Tc intervals from 415±26 to 409±27ms (p=0.3) on testosterone. Q-T intervals were longer in women compared with men under all conditions (p<0.03). The data support a direct effect of testosterone to shorten Q-T intervals in older men and older women in the absence of HR changes or hypogonadal status. Mean decreases are small and unlikely to affect risks of arrhythmic events in patients receiving Q-T prolonging medications.

Low free testosterone is associated with heart failure mortality in older men referred for coronary angiography

AIMS

Accumulating evidence suggests that androgen deficiency is associated with cardiovascular disease. We aimed at evaluating whether total testosterone (TT) and free testosterone (FT) are associated with specific cardiovascular events.

METHODS AND RESULTS

We measured TT and sex-hormone-binding globulin levels in 2078 men who were routinely referred for coronary angiography between 1997 and 2000. Free testosterone was calculated according to Vermeulen. Main outcome measures were Cox proportional hazard ratios (HRs) for sudden cardiac death, fatal myocardial infarction, death from congestive heart failure (CHF), as well as other cardiac deaths according to quartiles of TT and FT. The median follow-up time was 7.7 years. Multivariable adjusted HRs (with 95% confidence intervals) in the fourth compared with the first FT quartile and per 1 SD increase in FT for CHF mortality were 0.38 (0.17-0.87) and 0.37 (0.15-0.89), respectively. We observed no independent significant association of FT with sudden cardiac death, fatal myocardial infarction, or other cardiac death. There was no independent association of TT levels with cardiovascular events or cardiac disease.

CONCLUSION

Low levels of FT are independently associated with increased CHF mortality.