Arrhythmias and women

Review: Sex-related differences in the treatment of cardiac arrhythmia

Cardiac arrhythmias are a common and potentially serious cardiovascular disorders that affect both men and women. However, there is evidence to suggest that there may be sex-related differences in the prevalence, clinical presentation, and management of cardiac arrhythmias. Hormonal and cellular factors may play a role in these sex-specific differences. In addition, there are differences in the types of arrhythmias that men and women experience, with men more likely to experience ventricular arrhythmias and women more likely to experience supraventricular arrhythmias. The management of cardiac arrhythmias also differs between men and women. For example, some studies have found that women are less likely to receive appropriate treatment for arrhythmias and are more likely to have adverse outcomes following treatment. Despite these sex-related differences, the majority of research on cardiac arrhythmias has been conducted in men, and there is a need for more research to specifically examine the differences between men and women. This is especially important given that the prevalence of cardiac arrhythmia is increasing, and it is essential to understand how to effectively diagnose and treat these conditions in both men and women. In this review, we examine the current understanding of sex-related differences in cardiac arrhythmias. We also review the available data on sex-specific management strategies for cardiac arrhythmias and highlight areas of future research.

Sex Differences in Reported Adverse Drug Reactions to COVID-19 Drugs in a Global Database of Individual Case Safety Reports

Introduction

In late 2019, a new coronavirus—severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)—was discovered in Wuhan, China, and the World Health Organization later declared coronavirus disease 2019 (COVID-19) a pandemic. Numerous drugs have been repurposed and investigated for therapeutic effectiveness in the disease, including those from “Solidarity,” an international clinical trial (azithromycin, chloroquine, hydroxychloroquine, the fixed combination lopinavir/ritonavir, and remdesivir).

Objective

Our objective was to evaluate adverse drug reaction (ADR) reporting for drugs when used in the treatment of COVID-19 compared with use for other indications, specifically focussing on sex differences.

Method

We extracted reports on COVID-19-specific treatments from the global ADR database, VigiBase, using an algorithm developed to identify reports that listed COVID-19 as the indication. The Solidarity trial drugs were included, as were any drugs reported ≥ 100 times. We performed a descriptive comparison of reports for the same drugs used in non-COVID-19 indications. The data lock point date was 7 June 2020.

Results

In total, 2573 reports were identified for drugs used in the treatment of COVID-19. In order of frequency, the most reported ADRs were electrocardiogram QT-prolonged, diarrhoea, nausea, hepatitis, and vomiting in males and diarrhoea, electrocardiogram QT-prolonged, nausea, vomiting, and upper abdominal pain in females. Other hepatic and kidney-related events were included in the top ten ADRs in males, whereas no hepatic or renal terms were reported for females. COVID-19-related reporting patterns differed from non-pandemic reporting for these drugs.

Conclusion

Review of a global database of suspected ADR reports revealed sex differences in the reporting patterns for drugs used in the treatment of COVID-19. Patterns of ADR sex differences need further elucidation.

Electronic supplementary material

The online version of this article (10.1007/s40264-020-01000-8) contains supplementary material, which is available to authorized users.

Ventricular tachycardia in a primigravida with Hyperemesis Gravidarum

Hyperemesis gravidarum is persistent vomiting, seen more often in the first trimester of pregnancy, when the patient is unable to maintain adequate hydration. Intractable vomiting can lead to severe electrolyte imbalance, which may cause electrocardiogram abnormalities. Occasionally, ventricular tachycardia can complicate a pregnancy. Although its occurrence usually indicates an underlying cardiac structural or arrhythmic abnormality, it may rarely occur in a pregnant patient with structurally normal heart. We report a rare case of ventricular tachycardia, secondary to hyperemesis induced hypomagnesemia and hypokalemia, in a pregnant patient with a structurally normal heart.

Long-Term Evaluation of Biotronik Linox and Linox(smart) Implantable Cardioverter Defibrillator Leads

INTRODUCTION

Expert consensus holds that post-market, systematic surveillance of ICD leads is essential to ensure confirmation of adequate lead performance. GALAXY (NCT00836589) and CELESTIAL (NCT00810264) are ongoing multicenter, prospective, non-randomized registries conducted to confirm the long-term safety and reliability of Biotronik leads.

METHODS AND RESULTS

ICD and CRT-D patients are followed for Linox and Linox(smart) ICD lead performance and safety for 5 years post-implant. All procedural and system-related adverse events (AEs) were assessed at each follow-up, along with lead electrical parameters. An independent CEC of EPs adjudicated AEs to determine AE category and lead relatedness. The analysis used categories of lead observations per ISO 5841-2 (Third edition). A total of 3,933 leads were implanted in 3,840 patients (73.0% male, mean age 67.0 ± 12.2 years) at 146 US centers. The estimated cumulative survival probability was 96.3% at 5 years after implant for Linox leads and 96.6% at 4 years after implant for Linox(smart) leads. A comparison of the Linox and Linox(smart) survival functions did not find evidence of a difference (P = 0.2155). The most common AEs were oversensing (23, 0.58%), conductor fracture (14, 0.36%), failure to capture (13, 0.33%), lead dislodgement (12, 0.31%), insulation breach (10, 0.25%), and abnormal pacing impedance (8, 0.20%).

CONCLUSIONS

Linox and Linox(smart) ICD leads are safe, reliable and infrequently associated with lead-related AEs. Additionally, estimated cumulative survival probability is clinically acceptable and well within industry standards. Ongoing data collection will confirm the longer-term safety and performance of the Linox family of ICD leads.

Sex differences in congenital heart defects and genetically induced arrhythmias

Sex medicine can be applied to define the effect of male or female sex-associated differences on the prevalence of congenital heart defects (CHDs), on clinical manifestation of the latter, on means of dealing with the defects and facing consequent surgical treatment, as well as on the success of surgery. The widespread use of modern databases has undoubtedly enhanced the possibility of these observations compared to the past, when findings were limited to case series from single cardiology or paediatric heart surgery units. The aim of the present review is to assess all publications present in the literature on sex differences and CHD, placing particular emphasis on both contradictory aspects and less acknowledged issues. Furthermore, a section of the review is devoted to the effect of sex differences on cardiac arrhythmias, particularly the largely genetically predetermined electrophysiological differences observed between men and women.

Gender differences in patients with atrial fibrillation

AIMS

We aimed to compare gender differences with respect to presentation of consecutive ambulatory patients with atrial fibrillation (AF), management of their disease, and outcomes.

METHODS

Post-hoc analysis of an observational (non-interventional) study performed by 616 office- and hospital-based cardiologists in Germany. Consecutive (mainly ambulatory) patients with Electrocardiography (ECG) -confirmed AF and available data from baseline (BL) and two follow-up visits at 6 and 12 months were assessed.

RESULTS

A total of 2,742 patients (62.8% males, mean age 67.5 years; 37.2% women, mean age 71.2 years) were analysed. Women had more frequently paroxysmal and less frequently permanent AF. Quality of life scores were slightly worse in women compared to men, for all types of AF. For class III anti-arrhythmic drugs at baseline (more frequent in men), and for digitalis (less frequent in men at BL and 1 year) statistically significant differences were noted. Oral anti-coagulation (OAC) without anti-platelet drugs was given in 67.9% at BL and in 62.7% at 1 year (no differences between genders). During follow-up, drug conversions in men/women were reported in 12.3%/14.9% (p=0.054), and electrical conversions in 14.6%/11.7% (p=0.03). Hospitalisations occurred in 25.9% and strokes in 3.5%. Patients with higher CHA2DS2-VASc scores had increased stroke rates (0, 1 and ≥2 points: 0.0, 1.5 and 3.9%, respectively; with no significant gender differences).

CONCLUSION

In everyday management of patients with AF, there were no differences in treatment and major outcomes, in particular stroke, between women and men. This finding is opposed to earlier studies reporting OAC undertreatment of women and higher stroke rates.

Gender-related differences in presentation, treatment and long-term outcome in patients with first-diagnosed atrial fibrillation and structurally normal heart: the Belgrade atrial fibrillation study

BACKGROUND

Several studies have investigated gender-related differences in atrial fibrillation (AF), but limited data are available in relation to gender-related differences in presentation, treatment and long-term outcomes of patients with first-diagnosed AF and structurally normal heart.

OBJECTIVE

To compare gender-related clinical characteristics, presentation, treatment and long-term outcomes in a cohort of patients with first-diagnosed non-valvular AF and a structurally normal heart, following a 10-year follow-up.

METHODS

Observational cohort study of patients with AF between 1992 and 2007.

RESULTS

Of 862 patients (mean age 52.2±12.1 years), 315 (36.5%) were female. Paroxysmal AF and hypertension were significantly more prevalent in females, while persistent AF was more common amongst males (all p<0.001). Female patients were more symptomatic (p=0.002). After a mean follow-up of 10.1±6.1 years, more male patients developed tachycardiomyopathy (6.0% vs. 1.9%, p=0.02). In multivariate analysis, male gender remained significantly associated with tachycardiomyopathy (HR 3.1, 95% CI: 1.3-7.4, p=0.012). The rate of transition to permanent AF, thromboembolism, hemorrhage, all-cause mortality, cardiovascular and sudden death did not significantly differ between male and female patients.

CONCLUSIONS

Gender differences are evident in AF. Male patients were less asymptomatic or more frequently developed persistent AF. Male patients were also at higher risk of tachycardiomyopathy, suggesting that these patients require more attention to rate control during follow-up.

Ventricular tachycardia in pregnant patients

Ventricular tachycardia although not common, can occasionally complicate pregnancy. Its presence may indicate an underlying cardiac structural abnormality, or undiagnosed congenital arrhythmic disease. However, some pregnant patients with ventricular tachycardia have structurally normal hearts. Two cases of ventricular tachycardia in pregnant patients with structurally normal hearts are presented and an approach to diagnosis and management of such patients are discussed.

Fatal cardiotoxicity related to halofantrine: a review based on a worldwide safety data base

Background

Halofantrine (HF) was considered an effective and safe treatment for multi-drug resistant falciparum malaria until 1993, when the first case of drug-associated death was reported. Since then, numerous studies have confirmed cardiac arrythmias, possibly fatal, in both adults and children. The aim of the study was to review fatal HF related cardiotoxicity.

Methods

In addition, to a systematic review of the literature, the authors have had access to the global safety database on possible HF related cardiotoxicity provided by GlaxoSmithKline.

Results

Thirty-five cases of fatal cardiotoxicity related to HF, including five children, were identified. Females (70%) and patients from developing countries (71%) were over-represented in this series. Seventy-four percent of the fatal events occurred within 24 hours of initial exposure to HF. Twenty six patients (74%) had at least one predisposing factor for severe cardiotoxicity, e.g., underlying cardiac disease, higher than recommended doses, or presence of a concomitant QT-lengthening drug. All (100%) of the paediatric cases had either a contraindication to HF or an improper dose was given. In six cases there was no malaria.

Conclusion

A distinction should be made between common but asymptomatic QT-interval prolongation and the much less common ventricular arrhythmias, such as torsades de pointes, which can be fatal and seem to occur in a very limited number of patients. The majority of reported cardiac events occurred either in patients with predisposing factors or with an improper dose.

Therefore, in the rare situations in which HF is the only therapeutic option, it can still be given after carefully checking for contraindications, such as underlying cardiac disease, bradycardia, metabolic disorders, personal or family history of long QT-interval or concomitant use of another QT-prolonging drug (e.g., mefloquine), especially in females.

Women with dysrhythmia: a clinical challenge

There are identified differences in the electrophysiology structure and measurements in women and men. An understanding of these differences and of the increased incidence and prevalence of dysrhythmias in women, the differences in presentation, and the differences in risk factors for these dysrhythmias will help guide treatment decisions. As new knowledge is gained through research, practitioners can provide gender-specific care to women who have or are at increased risk of cardiac dysrhythmia.

Characteristics of hospitalized patients with atrial fibrillation in Taiwan: a nationwide observation

PURPOSE

The aim of the study is to describe the nationwide epidemiological data for hospitalized patients with atrial fibrillation in Taiwan.

METHODS

We collected information on hospitalized patients with discharge-diagnosed atrial fibrillation from 1997 through 2002 from the Taiwan National Health Insurance database. Patients were examined for temporal trends in the frequency of the disease, clinical characteristics, and in-hospital mortality.

RESULTS

Of 162,340 patients (mean age, 73.8 years), 55.3% were men and 38.6% had a primary diagnosis of atrial fibrillation. The mean annual frequency of diagnosed atrial fibrillation was 127 per 100,000 persons. The frequency of atrial fibrillation rose from 91 (1997) to 150 (2002) per 100,000 persons (P <.001); it significantly increased directly with age from 4 per 100,000 in patients <50 years to 1571 per 100,000 in patients > or =80 years. The frequency was significantly higher in men than in women (137 vs 116 per 100,000; P <.001). The average in-hospital mortality rate was 9.3%. In-hospital mortality rate showed a decreasing trend (9.9% vs 7.6%; P = .003). Comorbidities of ischemic heart disease, valvular heart disease, hypertension, ischemic stroke, and congestive heart failure were predictors of higher mortality.

CONCLUSIONS

This Taiwanese study showed a 1.65-fold increase in the frequency of diagnosed atrial fibrillation during the study period. The in-hospital mortality rate, however, declined. The frequency of atrial fibrillation was higher in men and the elderly. We should be more concerned about negative outcomes in hospitalized patients with atrial fibrillation and other coexisting cardiovascular conditions.

Gender differences in arrhythmias

Electrocardiographic and electrophysiologic differences between men and women have long been noted. Women have a higher intrinsic heart rate than men, along with a longer corrected QT interval and a shorter sinus nodal recovery time. The incidence of and risk factors for a variety of arrhythmias differ between men and women. Atrioventricular nodal reentry tachycardia has a 2:1 female-to-male predominance, while accessory pathways are twice as frequent in men. Although atrial fibrillation is more prevalent in men of all age groups, the absolute numbers of men and women with atrial fibrillation are equal, and the associated morbidity and mortality experienced by women with atrial fibrillation appear to be worse. Women have a lower incidence of sudden cardiac death, and female survivors of sudden cardiac death have a lower frequency of spontaneous or inducible ventricular tachycardia. On the other hand, drug-induced torsade de pointes and symptomatic long QT syndrome have a female predominance. Therefore, greater caution should be used when prescribing QT-prolonging drugs in women. The incidence of arrhythmias is increased during pregnancy, and management of pregnant patients poses a significant challenge. The mechanisms of these gender differences are unclear but may be related to hormonal effects and the shorter QT interval in adult males. Pharmacologic and nonpharmacologic therapies are usually equally efficacious, but the risks of pharmacologic therapy are different in men and women. Atrial fibrillation may be more difficult to treat in women.

An evaluation of the impact of gender and age on QT dispersion in healthy subjects

OBJECTIVES

To determine if gender, age, and gender per age category, have an impact on QT and QTc dispersion in healthy volunteers.

METHODS

This study was undertaken in 150 patients (50 per age group, 75 males, 75 females). The age groups included young (20-40 years), middle-aged (41-69 years) and elderly (> 70 years) subjects. The QT intervals on a 12 lead ECG were determined and Bazett's formula was used to derive the QTc intervals. The QT and QTc dispersion were determined by subtracting the shortest QTc interval from the longest on each 12-lead recording.

RESULTS

Males had higher QT dispersion than females (50 +/- 22 vs 42 +/- 18 ms, P = 0.017) but QTc dispersion was not significantly changed. No significant differences were seen among the different age categories for QT or QTc dispersion. In elderly subjects, males had higher QT and QTc dispersion than females (54 +/- 23 vs 42 +/-15 ms, P = 0.039 and 63 +/- 23.7 vs 48 +/- 21 ms, P = 0.032, respectively).

CONCLUSIONS

When evaluating the effect of gender in different age categories, elderly males have significantly greater QT and QTc dispersion than elderly female subjects. No other gender differences were noted for QT or QTc dispersion in the other two age categories. When evaluating a population of healthy volunteers, regardless of age, gender has an impact on QT dispersion but no significant interaction with QTc dispersion. Evaluating age without dividing the data by gender yields no significant differences in QT or QTc dispersion.

Comparison of contractile responses in isolated mouse aorta and pulmonary artery: Influence of strain and sex

Transgenic mice are often used to study the physiologic role of a known gene. The design of experiments with transgenic mice usually does not take into account strain and sex differences, at least in isolated vessels. Therefore, we have compared the contractile response of isolated aortae and isolated pulmonary arteries of male and female mice of different strains (CD1, BL6, and DBA). Contractile stimulation was achieved by depolarization due to KCl, alpha1-adrenoceptor stimulation by phenylephrine and inhibition of protein phosphatase activity by cantharidin. In isolated aorta, strain-specific differences in contractility and sex-specific differences could be observed. The concentration of phenylephrine (PE) inducing half maximal contraction (EC50) was different between aortae from DBA male mice and the other strains tested. Phasic contractions of isolated aortic rings due to PE were seen in all mice except DBA male. In isolated pulmonary arteries, strain-specific differences and sex-specific differences could be observed. The EC50-values of PE were not different between all groups. Phasic contractions due to PE were only seen in pulmonary arteries from CD1 male and BL6 female. In conclusion, strain- and sex-specific differences should be considered in selecting mice used for transgenesis or gene targeting experiments.

Sex Differences in Susceptibility to Epinephrine-Induced Arrhythmias

Gender differences in incidence of cardiac arrhythmias have been documented. It is generally believed that cardiac pathology provides an arrhythmogenic substrate but that a trigger such as sympathetic nervous system activation is required to initiate arrhythmias. This study was done to determine whether there is a sex difference in susceptibility to epinephrine-induced arrhythmias in healthy rats without preexisting pathology and to determine whether gonadal hormones play a role in development of arrhythmias. Untreated, sham-operated, and gonadectomized male and female rats were anesthetized and given IV boluses of epinephrine. ECG, heart rate, and blood pressure were measured continuously for 1 minute and intermittently over a period of 30 minutes. Male rat hearts have a higher occurrence and frequency of epinephrine-induced premature ventricular contractions, missed beats, and blocks than female rat hearts. Ovariectomy increases arrhythmias, thereby abolishing the female advantage. Castration has no effect on occurrence and frequency of premature ventricular contractions but attenuates missed beats and blocks. Sex differences and effect of gonadectomy on epinephrine-induced alterations in heart rate and blood pressure implicate baroreceptor reflex in the dimorphic arrhythmogenic response. Male rat hearts are more susceptible than female hearts to epinephrine-induced arrhythmias, and gonadal hormones play a role in this disparity.

Cardiac pathologic findings reveal a high rate of sudden cardiac death of undetermined etiology in younger women

BACKGROUND

Between 1989 and 1998 there was a 21% increase in estimated sudden cardiac death among US women aged 35 to 44 years. In contrast, the sudden cardiac death rate in age-matched men showed a decreasing trend (-2.8%). Due to under-representation of younger adults in published autopsy series, etiologies of sudden cardiac death merit further investigation.

METHODS

We reviewed autopsy and detailed cardiac pathologic findings in younger women (age 35-44 years) from a 270-patient, 13-year (1984-1996) autopsy series of sudden cardiac death, and performed comparisons with findings in age-matched men.

RESULTS

Women aged 35 to 44 years constituted 32% of all women in the series compared to men, who constituted 24% of total men (P =.004 vs women). A presumptive cause of sudden cardiac death could not be determined in 13 women (50%). Among women, 6 cases (22%) had significant coronary artery disease. Findings in others included coronary artery anomalies (n = 3), myocarditis (n = 2), hypertrophic cardiomyopathy (n = 1), coronary artery dissection (n = 1) and accessory pathway (n = 1). In younger men, a presumptive cause of sudden cardiac death remained undetermined in only 24% (P =.025 vs younger women), and coronary artery disease accounted for 40% of cases.

CONCLUSIONS

In younger women, despite autopsy and detailed cardiac pathologic examination, an attributable cause of sudden cardiac death was not determined in 50% of cases; a 2-fold increase compared to men of the same age. Given the dynamic and multifactorial nature of sudden cardiac death, comprehensive population-based investigations are likely to be necessary to further investigate this unexpected sex-based disparity.

Gender, ethnicity, and genes in cardiovascular disease. Part 2: implications for pharmacotherapy

Women are underrepresented in clinical trials. Lower doses of beta-blockers are required for Southeast Asians. ACE and ARB's are teratogenic in the second trimester. Torsades de Pointes is more common in women related to a longer QT-interval. Lower dose OCPs decrease the risk of MI, stroke and thrombosis. HRTs are not effective for CAD prevention.

Anorexia nervosa medical issues

Anorexia nervosa is an increasingly common chronic psychiatric disorder with a multitude of medical complications. Most of these complications are reversible if there is timely restoration of body weight. A few of them, particularly osteoporosis, refeeding complications, and cardiac arrhythmia, are potentially much more serious. In the end, a multidisciplinary team approach with input from a primary care provider who is familiar with these medical sequelae, together with psychiatric and dietary expertise, can effectuate a successful outcome.

Cardiac arrhythmias in pregnancy: clinical and therapeutic considerations

Pregnancy can precipitate cardiac arrhythmias not previously present in seemingly well individuals. Risk of arrhythmias is relatively higher during labor and delivery. Potential factors that can promote arrhythmias in pregnancy and during labor and delivery include the direct cardiac electrophysiological effects of hormones, changes in autonomic tone, hemodynamic perturbations, hypokalemia of pregnancy, and underlying heart disease. Paroxysmal supraventricular and ventricular tachycardia may cause hemodynamic compromise with consequences to the fetus. Management of arrhythmias in pregnant women is similar to that in non-pregnant but a special consideration must be given to avoid adverse fetal effects. No drug therapy is usually needed for the management of supraventricular or ventricular premature beats, but potential stimulants, such as smoking, caffeine, and alcohol should be eliminated. In paroxysmal supraventricular tachycardia, vagal stimulation maneuvers should be tried first. Adenosine or a cardioselective beta-blocker could be used if vagal maneuvers are ineffective. Alternatively, verapamil or diltiazem may be given. In pregnant women with atrial fibrillation, the goal of treatment is conversion to sinus rhythm or to control ventricular rate by a cardioselective beta-adrenergic blocker drug or digoxin. Ventricular arrhythmias may occur in the pregnant women with cardiomyopathy, congenital heart disease, valvular heart disease, or mitral valve prolapse. Termination of ventricular arrhythmias can usually be achieved by intravenous lidocaine or procainamide or by electrical cardioversion. Amiodarone is not safe for the fetus. Beta-blocker therapy must be continued during pregnancy and postpartum period in women with long QT syndrome and torsade de pointes.

Gender, ethnicity and genetics in cardiovascular disease: part 1: Basic principles

Prior to 1993, most drug efficacy and safety trials were conducted in white males, although gender and racial differences in pharmacodynamics and pharmacokinetics have been documented since the early 1900s. Over the last 2 decades, supported by the FDA and legislation, attempts to include more women and minorities in clinical drug trials have been made, with limited success. Yet, there are important differences in pathophysiology and pharmacogenetics, as well as pharmacotherapeutic effectiveness. This is the first of 2 articles that review the basic scientific principles of such differences. In particular, genetic polymorphisms of cardiovascular candidate genes and drug metabolism are described. The pharmacodynamic and pharmacokinetic variations among genders and ethnicities are summarized.

Resultados perinatológicos del servicio de Cardiopatía y Embarazo del Hospital Ginecobstétrico "Ramón González Coro" en el bienio 2000-2001, Habana

OBJETIVOS: establecer las bases para el tratamiento y atención de la mujer portadora de cardiopatía en edad fértil, caracterizando al grupo de gestantes atendidas en servicio. MÉTODOS: realizó un estudio descriptivo y las mujeres fueran clasificadas según cardiopatía y grado de afectación funcional en relación con los resultados, se decribiendo las complicaciones durante el embarazo, parto y puerperio y los resultados perinatales. Variables analizadas: tipo de cardiopatía y clasificación funcional de las mismas, complicaciones obstétricas y/o cardiovasculares, edad gestacional al parto, modo de nacimiento, peso y puntaje de Apgar en el recién nacido y mortalidad materna y del recién nacido. RESULTADOS: encontramos 129 valvulopatías adquiridas, 79 congénitas, 18 casos de trastornos del ritmo. Lesiones más frecuentes valvulopatías mitrales (92) y comunicaciones interauriculares (31). 21 pacientes presentaron empeoramiento funcional durante el embarazo. Aparecieron complicaciones cardiovasculares en 19 pacientes y obstétricas en 142. 14 requirieron ingreso en Servicios de Terapia Intensiva y tres fallecieron. CONCLUSIONES: Se confirmó la asociación entre clasificación funcional y complicaciones cardiovasculares durante el embarazo, parto y puerperio. Las complicaciones obstétricas se comportan igual que en las gestaciones de pacientes sanas y más de la mitad de los partos fueron eutócicos.

Age, gender, and autonomic tone effects on surface electrocardiographic indices of ventricular repolarization

BACKGROUND

Prolonged QT offset dispersion (QToD), an index of heterogeneity of ventricular repolarization, is thought to be an independent predictor of all-cause and cardiovascular mortality. However the influence of gender and autonomic tone in healthy adults on age-related changes in measures of ventricular repolarization are not well characterized.

METHODS

QToD and T wave complexity were measured in 56 healthy subjects with no detectable heart disease (by echo and stress test)-38 young subjects with a mean age of 28 +/- 4 years and 18 old subjects with a mean age of 71 +/- 7 years. QToD and T wave complexity were computed from 12-lead ECGs using the GE Marquette QT Guard automated analysis program with manual overreading at rest (baseline), following exercise, and double autonomic blockade with atropine and propranolol. Data was analyzed using factorial ANOVA.

RESULTS

Young males had a significantly greater QToD than young and old females at baseline (28 +/- 5 ms, 23 +/- 5 ms, and 22 +/- 5 ms, respectively, P < 0.01), an intrinsic effect independent of changes in autonomic tone. In contrast, females had significantly greater T wave complexity than males following exercise and double autonomic blockade with a definite trend at baseline. There was no correlation between T wave complexity and QToD.

CONCLUSIONS

Age and gender demonstrate a complex interaction on indices of myocardial repolarization with different measures behaving differently. These findings have implications for better understanding age and gender effects on myocardial electrophysiology.

New-Onset Atrial Fibrillation

Background —Although sex differences in coronary artery disease have received considerable attention, few studies have dealt with sex differences in the most common sustained cardiac arrhythmia, atrial fibrillation (AF). Differences in presentation and clinical course may dictate different approaches to detection and management. We sought to examine sex-related differences in presentation, treatment, and outcome in patients presenting with new-onset AF.

Methods and Results —The Canadian Registry of Atrial Fibrillation (CARAF) enrolled subjects at the time of first ECG-confirmed diagnosis of AF. Participants were followed at 3 months, at 1 year, and annually thereafter. Treatment was at the discretion of the patients’ physicians and was not directed by CARAF investigators. Baseline and follow-up data collection included a detailed medical history, clinical, ECG, and echocardiographic measures, medication history, and therapeutic interventions. Three hundred thirty-nine women and 560 men were followed for 4.14±1.39 years. Compared with men, women were older at the time of presentation, more likely to seek medical advice because of symptoms, and experienced significantly higher heart rates during AF. Compared with older men, older women were half as likely to receive warfarin and twice as likely to receive acetylsalicylic acid. Compared with men on warfarin, women on warfarin were 3.35 times more likely to experience a major bleed.

Conclusions —Anticoagulants are underused in older women with AF relative to older men with AF, despite comparable risk profiles. Women receiving warfarin have a significantly higher risk of major bleeding, suggesting the need for careful monitoring of anticoagulant intensity in women.

Reversing sevoflurane-associated Q-Tc prolongation by changing to propofol

Congenital or acquired forms of the long Q-T syndrome may result in ventricular tachycardia known as torsade de pointes. Many drugs including volatile anaesthetics modify the Q-T interval. Sevoflurane is known to prolong of the rate-corrected Q-T interval (Q-Tc). The objective of this study was to determine whether the sevoflurane-associated Q-Tc prolongation is rapidly reversible when propofol is substituted for sevoflurane. Thirty-two female patients were allocated to two groups. All patients received sevoflurane induction and anaesthesia for 15 min. In one group, sevoflurane was then discontinued and anaesthesia maintained on propofol for another 15 min. The second group received sevoflurane anaesthesia for 30 min. Measurements were taken before, and 15, 20, 25 and 30 min after induction. Q-Tc prolongation was significantly reduced 5, 10 and 15 min after propofol had been substituted for sevoflurane. We conclude that the sevoflurane-associated Q-Tc prolongation is fully reversible within 15 min when propofol is substituted for sevoflurane.

Sevoflurane, but not propofol, significantly prolongs the Q-T interval

Prolongation of the Q-T interval may be associated with polymorphic ventricular tachycardia known as torsade de pointes, syncope and sudden death. Existing data show that isoflurane prolongs the Q-T interval, whereas halothane shortens it. The aim of this study was to determine whether sevoflurane or propofol affects the Q-T interval. Thirty female patients undergoing gynecologic surgery were randomly assigned to two groups, one receiving inhaled induction with sevoflurane and the other receiving total IV anesthesia with propofol. Before and 20 min after the induction, a six-lead electrocardiogram was recorded, and blood pressure was measured. The Q-T interval and heart rate adjusted Q-T interval (Q-Tc interval) were significantly prolonged during the administration of anesthesia with sevoflurane, while the Q-T interval was significantly shortened, and the Q-Tc interval was statistically unaffected during propofol anesthesia administration. We conclude that, in otherwise healthy female patients, sevoflurane prolongs the Q-Tc.

IMPLICATIONS

In this study, we evaluated the effect of sevoflurane induction and anesthesia versus propofol induction and anesthesia on the Q-T interval. Sevoflurane significantly prolonged the Q-T interval and the heart rate adjusted Q-T interval, whereas propofol shortened the Q-T interval but not the heart rate adjusted Q-T interval.