Should there be sex-specific criteria for the diagnosis and treatment of heart failure?

Sex differences in atrial fibrillation ablation outcomes in patients with heart failure

BACKGROUND

There is a lack of data on the impact of sex on the outcomes of patients with heart failure (HF) undergoing atrial fibrillation (AF) ablation. We aimed to analyze the association of sex with outcomes of atrial fibrillation ablation in patients with heart failure.

METHODS

The National Readmissions Database (NRD) was analyzed from 2016 to 2019 to identify patients ≥ 18 years old with heart failure (HF) undergoing AF ablation. The outcomes of interest included peri-procedural complications, in-hospital mortality, resource utilization, and unplanned 1-year readmissions. The final cohort was divided into patients with HFrEF and HFpEF and outcomes were compared between males and females in both cohorts.

RESULTS

A total of 23,277 patients with HF underwent AF ablation between 2016 and 2019, of which 14,480 had HFrEF and 8,797 had HFpEF. Among patients with HFrEF, 61.6% were males and 38.4% were females whereas, among patients with HFpEF, 35.4% were males and 64.6% were females. On a multivariable-adjusted analysis, in patients with HFrEF, there was no difference in the odds of in-hospital mortality, peri-procedural complications, or 1-year HF-related/AF-related/all-cause readmissions between males and females. In patients with HFpEF, females had a higher risk 1-year HF-related readmissions (adjusted hazards ratio: 1.46; 95% CI: 1.13-1.87; p = 0.01), without any difference in the 1-year AF-related/all-cause readmissions, in-hospital mortality, or peri-procedural complications.

CONCLUSION

Our results show that females with HFrEF undergoing AF ablation have similar outcomes whereas females with HFpEF have higher 1-year HF readmissions with no difference in the other outcomes, compared to males.

Sex and gender differences in myocarditis and dilated cardiomyopathy: An update

In the past decade there has been a growing interest in understanding sex and gender differences in myocarditis and dilated cardiomyopathy (DCM), and the purpose of this review is to provide an update on this topic including epidemiology, pathogenesis and clinical presentation, diagnosis and management. Recently, many clinical studies have been conducted examining sex differences in myocarditis. Studies consistently report that myocarditis occurs more often in men than women with a sex ratio ranging from 1:2-4 female to male. Studies reveal that DCM also has a sex ratio of around 1:3 women to men and this is also true for familial/genetic forms of DCM. Animal models have demonstrated that DCM develops after myocarditis in susceptible mouse strains and evidence exists for this progress clinically as well. A consistent finding is that myocarditis occurs primarily in men under 50 years of age, but in women after age 50 or post-menopause. In contrast, DCM typically occurs after age 50, although the age that post-myocarditis DCM occurs has not been investigated. In a small study, more men with myocarditis presented with symptoms of chest pain while women presented with dyspnea. Men with myocarditis have been found to have higher levels of heart failure biomarkers soluble ST2, creatine kinase, myoglobin and T helper 17-associated cytokines while women develop a better regulatory immune response. Studies of the pathogenesis of disease have found that Toll-like receptor (TLR)2 and TLR4 signaling pathways play a central role in increasing inflammation during myocarditis and in promoting remodeling and fibrosis that leads to DCM, and all of these pathways are elevated in males. Management of myocarditis follows heart failure guidelines and there are currently no disease-specific therapies. Research on standard heart failure medications reveal important sex differences. Overall, many advances in our understanding of the effect of biologic sex on myocarditis and DCM have occurred over the past decade, but many gaps in our understanding remain. A better understanding of sex and gender effects are needed to develop disease-targeted and individualized medicine approaches in the future.

Cardiovascular Disease in Women: What the Radiologist Needs to Know

BACKGROUND

 Sex-specific disparities are well documented for cardiovascular disease (CVD). There are differences in physiology and pathophysiology, pain perception, spectrum of disease, risk, therapeutic aspects, prognosis, and outcome. CVD represents a broad spectrum of disorders. This review focuses on cardiovascular and cardiac pathology.

METHOD

 This review summarizes the current state of the literature on cardiovascular disease in women from a radiological viewpoint. It aims to provide a deeper understanding of these differences and thereby alerts the reader to the potential of CT and MRI for diagnosing CVD in women. Special attention is paid to disparities in the underlying physiological and pathophysiological processes, clinical presentation, and the quality of care to provide a deep understanding of the topic. Cardiovascular and cardiac pathologies with a sex-specific pattern of disease are presented and typical CT and MRI findings are arranged and illustrated with imaging findings.

RESULTS AND CONCLUSION

 Sex-specific differences are not only sex hormonal in nature but are rooted in the epigenome and encompass a multitude of physiological systems. In fact, cardiovascular disease shows sex-specific characteristics spanning from incidence to clinical presentation, course of disease, and prognosis. This is of significance regarding pretest probabilities, the power of tests, imaging strategies, and interpretation of imaging results. Key sex-specific issues encompass obstructive and non-obstructive coronary artery disease (CAD), microvascular angina, myocardial infarction with non-obstructive CAD, and coronary artery dissection. Sex-specific patterns are also noted in myocardial disease and heart failure such as pregnancy-related heart disease, Takotsubo syndrome, and anthracycline-induced cardiotoxicity.

KEY POINTS

  · Cardiovascular diseases have sex-specific characteristics.. · Imaging strategies and interpretation of imaging results should be adjusted for women.. · Imaging helps in the improvement of the sex-specific management of cardiovascular disease..

Sex differences in atrial remodeling and its relationship with myocardial fibrosis in hypertrophic obstructive cardiomyopathy

BACKGROUND

This study aimed to explore the effect of sex on left atrial (LA) remodeling and its relationship with myocardial fibrosis in patients with hypertrophic obstructive cardiomyopathy (HOCM).

METHODS AND RESULTS

A total of 85 patients with HOCM were enrolled. Myocardial fibrosis was quantified by the collagen volume fraction (CVF) in myocardial samples. The early atrial peak of emptying rate (PER-E) was assessed by LA volume/time (V/t) curves derived from cardiac magnetic resonance (CMR) imaging analysis. The PER-E index was PER-E normalized by left ventricular (LV) filling volume. Patients with HOCM showed a lower PER-E index than healthy controls (P = 0.027). Compared with men, the PER-E (P < 0.001) and the PER-E indexes (P = 0.012) in women were lower. In CVF-stratified subgroups, a sex difference in the PER-E index was eliminated (P > 0.05). The CVF was correlated with the PER-E and PER-E indexes in both sexes (all P-values were <0.05). In multivariate regression analysis, sex (P = 0.007) and CVF (P < 0.001) were independently correlated with PER-E (all P-values were <0.05).

CONCLUSION

Patients with HOCM presented LA reverse remodeling. Impaired LA function was more common in female patients with HOCM due to their susceptibility to myocardial fibrosis.

Mechanisms and implications of sex differences in cardiac aging

Aging promotes structural and functional remodeling of the heart, even in the absence of external factors. There is growing clinical and experimental evidence supporting the existence of sex-specific patterns of cardiac aging, and in some cases, these sex differences emerge early in life. Despite efforts to identify sex-specific differences in cardiac aging, understanding how these differences are established and regulated remains limited. In addition to contributing to sex differences in age-related heart disease, sex differences also appear to underlie differential responses to cardiac stress such as adrenergic activation. Identifying the underlying mechanisms of sex-specific differences may facilitate the characterization of underlying heart disease phenotypes, with the ultimate goal of utilizing sex-specific therapeutic approaches for cardiac disease. The purpose of this review is to discuss the mechanisms and implications of sex-specific cardiac aging, how these changes render the heart more susceptible to disease, and how we can target age- and sex-specific differences to advance therapies for both male and female patients.

The impact of patient sex on the response to intramyocardial mesenchymal stem cell administration in patients with non-ischaemic dilated cardiomyopathy

AIMS

Sex differences impact the occurrence, presentation, prognosis, and response to therapy in heart disease. Particularly, the phenotypic presentation of patients with non-ischaemic dilated cardiomyopathy (NIDCM) differs between men and women. However, whether the response to mesenchymal stem cell (MSC) therapy is influenced by sex remains unknown. We hypothesize that males and females with NIDCM respond similarly to MSC therapy.

METHODS AND RESULTS

Male (n = 24) and female (n = 10) patients from the POSEIDON-DCM trial who received MSCs via transendocardial injections were evaluated over 12 months. Endothelial function was measured at baseline and 3 months post-transendocardial stem cell injection (TESI). At baseline, ejection fraction (EF) was lower (P = 0.004) and end-diastolic volume (EDV; P = 0.0002) and end-systolic volume (ESV; P = 0.0002) were higher in males vs. females. In contrast, baseline demographic characteristics, Minnesota Living with Heart Failure Questionnaire (MLHFQ), and 6-min walk test (6MWT) were similar between groups. EF improved in males by 6.2 units (P = 0.04) and in females by 8.6 units (P = 0.04; males vs. females, P = 0.57). EDV and ESV were unchanged over time. The MLHFQ score, New York Heart Association (NYHA) class, endothelial progenitor cell-colony forming units, and serum tumour necrosis factor alpha improved similarly in both groups.

CONCLUSION

Despite major differences in phenotypic presentation of NIDCM in males and females, this study is the first of its kind to demonstrate that MSC therapy improves a variety of parameters in NIDCM irrespective of patient sex. These findings have important clinical and pathophysiologic implications regarding the impact of sex on responses to cell-based therapy for NIDCM.

Sex-Specific Associations of Risks and Cardiac Structure and Function With Microalbumin/Creatinine Ratio in Diastolic Heart Failure

Background: Heart failure with preserved ejection fraction (HFpEF) affects women more frequently than men. However, data on sex-specific associations of adverse health outcomes and left ventricular structure and function and with microalbuminuria in patients with HFpEF are scarce. Methods: In 1,334 participants enrolled in the Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist (TOPCAT) Trial, we estimated the sex-specific multivariable-adjusted risk and LV traits with urine microalbumin/creatine ratio (ACR), using Cox or linear regression. Results: In total, 604 (45.3%) were women. In multivariable-adjusted analyses, a doubling of ACR in both men and women was associated with higher posterior (+0.014 cm, p = 0.012/+0.012 cm, p = 0.033) wall thickness and left ventricular mass index (+2.55 mg/m2, p = 0.004/+2.45 mg/m2, p = 0.009), whereas was also associated with higher septal (+0.018 cm, p = 0.002) and left atrial volume index (+1.44 mL/m2, p = 0.001) in men. ACR was a key predictor of all-cause (HR, 1.11; p = 0.006) and cardiovascular (HR, 1.17; p = 0.002) death in women, whereas in men ACR was associated with HF hospitalization (HR, 1.23; p < 0.001), any hospitalization (HR, 1.06; p = 0.006), and myocardial infarction (HR, 1.19; p = 0.017). The interactions of sex with ACR were significant for hospitalization for heart failure and any hospitalization (p ≤ 0.034). Conclusions: Outcomes and cardiac structure and function in patients with HFpEF appear to be influenced by ACR that vary according to sex. In men, ACR was significant associated with LV diastolic function, hospitalization, and myocardial infarction, whereas in women was associated with mortality.

Primary Prevention of Heart Failure in Women

The incidence of heart failure (HF) is increasing, particularly among women, and constitutes a rapidly growing public health problem. The primary prevention of HF in women should involve targeted, sex-specific strategies to increase awareness, promote a heart healthy lifestyle, and improve treatments that optimally control the risk factors for HF with reduced ejection fraction and HF with preserved ejection fraction. Epidemiological and pathophysiological differences in both HF subtypes strongly suggest that sex-specific preventive strategies and risk factor reduction may be particularly beneficial. However, significant gaps in sex-specific knowledge exist and are impeding preventive efforts. To overcome these limitations, women need to be adequately represented in HF research, sex differences must be prospectively investigated, and effective sex-specific interventions should be incorporated into clinical practice guidelines. This review summarizes the existing evidence that supports the primary prevention of HF in women and identifies potential strategies that are most likely to be effective in reducing the burden of HF among women.

Reporting of sex as a variable in cardiovascular studies using cultured cells: A systematic review

Reporting the sex of biological material is critical for transparency and reproducibility in science. This study examined the reporting of the sex of cells used in cardiovascular studies. Articles from 16 cardiovascular journals that publish peer-reviewed studies in cardiovascular physiology and pharmacology in the year 2018 were systematically reviewed using terms "cultured" and "cells." Data were collected on the sex of cells, the species from which the cells were isolated, and the type of cells, and summarized as a systematic review. Sex was reported in 88 (38.6%) of the 228 studies meeting inclusion criteria. Reporting rates varied with Circulation, Cardiovascular Research and American Journal of Physiology: Heart and Circulatory Physiology having the highest rates of sex reporting (>50%). A majority of the studies used cells from male (54.5%) or both male and female animals (32.9%). Humans (31.8%), rats (20.4%), and mice (43.8%) were the most common sources for cells. Cardiac myocytes were the most commonly used cell type (37.0%). Overall reporting of sex of experimental material remains below 50% and is inconsistent among journals. Sex chromosomes in cells have the potential to affect protein expression and molecular signaling pathways and should be consistently reported.

Sex differences in inflammation, redox biology, mitochondria and autoimmunity

Autoimmune diseases are characterized by circulating antibodies and immune complexes directed against self-tissues that result in both systemic and organ-specific inflammation and pathology. Most autoimmune diseases occur more often in women than men. One exception is myocarditis, which is an inflammation of the myocardium that is typically caused by viral infections. Sex differences in the immune response and the role of the sex hormones estrogen and testosterone are well established based on animal models of autoimmune viral myocarditis as well as in mitochondrial function leading to reactive oxygen species production. RNA viruses like coxsackievirus B3, the primary cause of myocarditis in the US, activate the inflammasome through mitochondrial antiviral signaling protein located on the mitochondrial outer membrane. Toll-like receptor 4 and the inflammasome are the primary signaling pathways that increase inflammation during myocarditis, which is increased by testosterone. This review describes what is known about sex differences in inflammation, redox biology and mitochondrial function in the male-dominant autoimmune disease myocarditis and highlights gaps in the literature and future directions.

Gender Differences in Postoperative Outcomes After Cardiac Surgery

Women presenting for cardiac surgery tend to be older and have hypertension, diabetes, and overweight or underweight body mass index than men. Despite improvements in surgical techniques and medications, women have increased risk for morbidity and mortality after multiple types of cardiac surgery. Women presenting for transcatheter aortic valve replacement are older and frailer than men, and have increased risk of intraoperative complications, but lower mortality at mid- and long-term ranges compared with men. Adherence to recovery and rehabilitation from cardiac surgery is challenging for women. Solutions should focus on increased family support, and use of group exercise and activities.

Sex-Related Differences in the Extent of Myocardial Fibrosis in Patients With Aortic Valve Stenosis

OBJECTIVES

The aim of this study was to assess the effect of sex on myocardial fibrosis as assessed by using cardiac magnetic resonance (CMR) imaging in aortic stenosis (AS).

BACKGROUND

Previous studies reported sex-related differences in the left ventricular (LV) remodeling response to pressure overload in AS. However, there are very few data regarding the effect of sex on myocardial fibrosis, a key marker of LV decompensation and adverse cardiac events in AS.

METHODS

A total of 249 patients (mean age 66 ± 13 years; 30% women) with at least mild AS were recruited from 2 prospective observational cohort studies and underwent comprehensive Doppler echocardiography and CMR examinations. On CMR, T1 mapping was used to quantify extracellular volume (ECV) fraction as a marker of diffuse fibrosis, and late gadolinium enhancement (LGE) was used to assess focal fibrosis.

RESULTS

There was no difference in age between women and men (age 66 ± 15 years vs 66 ± 12 years; p = 0.78). However, women presented with a better cardiovascular risk profile than men with less hypertension, dyslipidemia, diabetes, and coronary artery disease (all, p ≤ 0.10). As expected, LV mass index measured by CMR imaging was smaller in women than in men (p < 0.0001). Despite fewer comorbidities, women presented with larger ECV fraction (median: 29.0% [25th to 75th percentiles: 27.4% to 30.6%] vs. 26.8% [25th to 75th percentiles: 25.1% to 28.7%]; p < 0.0001) and similar LGE (median: 4.5% [25th-75th percentiles: 2.3% to 7.0%] vs. 2.8% [25th-75th percentiles: 0.6% to 6.8%]; p = 0.20) than men. In multivariable analysis, female sex remained an independent determinant of higher ECV fraction and LGE (all, p ≤ 0.05).

CONCLUSIONS

Women have greater diffuse and focal myocardial fibrosis independent of the degree of AS severity. These findings further emphasize the sex-related differences in LV remodeling response to pressure overload.

"Bridging the Gap" Everything that Could Have Been Avoided If We Had Applied Gender Medicine, Pharmacogenetics and Personalized Medicine in the Gender-Omics and Sex-Omics Era

Gender medicine is the first step of personalized medicine and patient-centred care, an essential development to achieve the standard goal of a holistic approach to patients and diseases. By addressing the interrelation and integration of biological markers (i.e., sex) with indicators of psychological/cultural behaviour (i.e., gender), gender medicine represents the crucial assumption for achieving the personalized health-care required in the third millennium. However, ‘sex’ and ‘gender’ are often misused as synonyms, leading to frequent misunderstandings in those who are not deeply involved in the field. Overall, we have to face the evidence that biological, genetic, epigenetic, psycho-social, cultural, and environmental factors mutually interact in defining sex/gender differences, and at the same time in establishing potential unwanted sex/gender disparities. Prioritizing the role of sex/gender in physiological and pathological processes is crucial in terms of efficient prevention, clinical signs’ identification, prognosis definition, and therapy optimization. In this regard, the omics-approach has become a powerful tool to identify sex/gender-specific disease markers, with potential benefits also in terms of socio-psychological wellbeing for each individual, and cost-effectiveness for National Healthcare systems. “Being a male or being a female” is indeed important from a health point of view and it is no longer possible to avoid “sex and gender lens” when approaching patients. Accordingly, personalized healthcare must be based on evidence from targeted research studies aimed at understanding how sex and gender influence health across the entire life span. The rapid development of genetic tools in the molecular medicine approaches and their impact in healthcare is an example of highly specialized applications that have moved from specialists to primary care providers (e.g., pharmacogenetic and pharmacogenomic applications in routine medical practice). Gender medicine needs to follow the same path and become an established medical approach. To face the genetic, molecular and pharmacological bases of the existing sex/gender gap by means of omics approaches will pave the way to the discovery and identification of novel drug-targets/therapeutic protocols, personalized laboratory tests and diagnostic procedures (sex/gender-omics). In this scenario, the aim of the present review is not to simply resume the state-of-the-art in the field, rather an opportunity to gain insights into gender medicine, spanning from molecular up to social and psychological stances. The description and critical discussion of some key selected multidisciplinary topics considered as paradigmatic of sex/gender differences and sex/gender inequalities will allow to draft and design strategies useful to fill the existing gap and move forward.

Sex-dependent association between inflammation, neural stress responses, and impaired myocardial function

PURPOSE

Evidence to date has failed to reveal unique female determinants of cardiovascular disease. However, a strong association was recently observed between increased metabolic activity in the amygdala, a neural centre involved in the processing of emotions, and impaired myocardial function in women, but not in men. Given the stronger immune responses in females, we sought to retrospectively investigate the interaction between inflammation, perceived stress, and myocardial injury.

METHODS

Overall, 294 patients (mean age 66.9 ± 10.0 years, 28.6% women) underwent both, ^99mTc-tetrofosmin single-photon emission computed tomography myocardial perfusion imaging and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography for the assessment of cardiac function, bone marrow metabolism (surrogate marker of inflammation), and resting amygdalar activity.

RESULTS

A positive association was found between amygdalar metabolism and ¹⁸F-FDG bone marrow uptake in women (r = 0.238, p = 0.029), but not in men (r = 0.060, p = 0.385). Linear regression models selected both, abnormal left ventricular ejection fraction (LVEF) and abnormal myocardial perfusion, as significant indicators of an increased amygdalar activity in women (B-coefficient LVEF, - 0.096; p = 0.021; abnormal myocardial perfusion, 3.227; p = 0.043), but not in men (bone marrow p = 0.076; abnormal myocardial perfusion p = 0.420). Accordingly, an interaction term consisting of sex and LVEF/abnormal myocardial perfusion was significant (p = 0.043 and p = 0.015, respectively).

CONCLUSIONS

Upregulated amygdalar metabolism is associated with an enhanced inflammatory state in female patients with impaired cardiac function. Given that enhanced activity of the limbic system is associated with worse cardiovascular outcomes, our study suggests that a focus on inflammatory markers and indicators of distress might help to tailor cardiovascular risk assessment and therapy towards the female cardiovascular phenotype.

Metabolic Activity in Central Neural Structures of Patients With Myocardial Injury

Background

Increasing evidence suggests a psychosomatic link between neural systems and the heart. In light of the growing burden of ischemic cardiovascular disease across the globe, a better understanding of heart‐brain interactions and their implications for cardiovascular treatment strategies is needed. Thus, we sought to investigate the interaction between myocardial injury and metabolic alterations in central neural areas in patients with suspected or known coronary artery disease.

Methods and Results

The association between resting metabolic activity in distinct neural structures and cardiac function was analyzed in 302 patients (aged 66.8±10.2 years; 70.9% men) undergoing fluor‐18‐deoxyglucose positron emission tomography and ^99mTc‐tetrofosmin single‐photon emission computed tomography myocardial perfusion imaging. There was evidence for reduction of callosal, caudate, and brainstem fluor‐18‐deoxyglucose uptake in patients with impaired left ventricular ejection fraction (<55% versus ≥55%: P=0.047, P=0.022, and P=0.013, respectively) and/or in the presence of myocardial ischemia (versus normal perfusion: P=0.010, P=0.013, and P=0.016, respectively). In a sex‐stratified analysis, these differences were observed in men, but not in women. A first‐order interaction term consisting of sex and impaired left ventricular ejection fraction or myocardial ischemia was identified as predictor of metabolic activity in these neural regions (left ventricular ejection fraction: P=0.015 for brainstem; myocardial ischemia: P=0.004, P=0.018, and P=0.003 for callosal, caudate, or brainstem metabolism, respectively).

Conclusions

Myocardial dysfunction and injury are associated with reduced resting metabolic activity of central neural structures, including the corpus callosum, the caudate nucleus, and the brainstem. These associations differ in women and men, suggesting sex differences in the pathophysiological interplay of the nervous and cardiovascular systems.

Extracellular matrix roles in cardiorenal fibrosis: Potential therapeutic targets for CVD and CKD in the elderly

Whereas hypertension, diabetes, and dyslipidemia are age-related risk factors for cardiovascular disease (CVD) and chronic kidney disease (CKD), aging alone is an independent risk factor. With advancing age, the heart and kidney gradually but significantly undergo inflammation and subsequent fibrosis, which eventually results in an irreversible decline in organ physiology. Through cardiorenal network interactions, cardiac dysfunction leads to and responds to renal injury, and both facilitate aging effects. Thus, a comprehensive strategy is needed to evaluate the cardiorenal aging network. Common hallmarks shared across systems include extracellular matrix (ECM) accumulation, along with upregulation of matrix metalloproteinases (MMPs) including MMP-9. The wide range of MMP-9 substrates, including ECM components and inflammatory cytokines, implicates MMP-9 in a variety of pathological and age-related processes. In particular, there is strong evidence that inflammatory cell-derived MMP-9 exacerbates cardiorenal aging. This review explores the potential therapeutic targets against CVD and CKD in the elderly, focusing on ECM and MMP roles.

Sex-related differences in chronic heart failure

The prevalence of chronic heart failure (CHF) is steadily increasing. Both sexes are affected, with significant differences in etiology, epidemiology and clinical presentation, prognosis, comorbidities, and response to treatment. Women tend to develop CHF at a more advanced age, present more often with HF with preserved ejection fraction, are more symptomatic, and have a worse quality of life than men, but also a better prognosis. In women, CHF has more frequently a non-ischemic etiology, and arterial hypertension and diabetes mellitus are leading comorbidities. Furthermore, many sex-related differences have been detected in the response to treatment, for example a greater prognostic benefit from angiotensin-receptor blockers in women, a higher incidence of complications after defibrillator implantation, and a greater response to cardiac resynchronization therapy. Furthermore, women are less likely to receive defibrillator therapy or heart transplantation. The significant underrepresentation of women in clinical trials limits our capacity to evaluate the extent of sex-related differences in CHF, although their characterization seems crucial in order to achieve the ultimate goal of a tailored therapy for this condition.

Mitochondria and Sex-Specific Cardiac Function

The focus of this chapter is the gender differences in mitochondria in cardiovascular disease. There is broad evidence suggesting that some of the gender differences in cardiovascular outcome may be partially related to differences in mitochondrial biology (Ventura-Clapier R, Moulin M, Piquereau J, Lemaire C, Mericskay M, Veksler V, Garnier A, Clin Sci (Lond) 131(9):803-822, 2017)). Mitochondrial disorders are causally affected by mutations in either nuclear or mitochondrial genes involved in the synthesis of respiratory chain subunits or in their posttranslational control. This can be due to mutations of the mtDNA which are transmitted by the mother or mutations in the nuclear DNA. Because natural selection on mitochondria operates only in females, mutations may have had more deleterious effects in males than in females (Ventura-Clapier R, Moulin M, Piquereau J, Lemaire C, Mericskay M, Veksler V, Garnier A, Clin Sci (Lond) 131(9):803-822, 2017; Camara AK, Lesnefsky EJ, Stowe DF. Antioxid Redox Signal 13(3):279-347, 2010). As mitochondrial mutations can affect all tissues, they are responsible for a large panel of pathologies including neuromuscular disorders, encephalopathies, metabolic disorders, cardiomyopathies, neuropathies, renal dysfunction, etc. Many of these pathologies present sex/gender specificity. Thus, alleviating or preventing mitochondrial dysfunction will contribute to mitigating the severity or progression of the development of diseases. Here, we present evidence for the involvement of mitochondria in the sex specificity of cardiovascular disorders.

Differences in Cardiovascular Aging in Men and Women

Cardiovascular diseases increase dramatically with age in both men and women. While it is clear that advanced age allows more time for individuals to be exposed to risk factors in general, there is strong evidence that age itself is a major independent risk factor for cardiovascular disease. Indeed, there are distinct age-dependent cellular, structural, and functional changes in both the heart and blood vessels, even in individuals with no clinical evidence of cardiovascular disease. Studies in older humans and in animal models of aging indicate that this age-related remodeling is maladaptive. An emerging view is that the heart and blood vessels accumulate cellular and subcellular deficits with age and these deficits increase susceptibility to disease in older individuals. Aspects of this age-dependent remodeling of the heart and blood vessels differ between the sexes. There is also new evidence that these maladaptive changes are more prominent in older animals and humans with a high degree of frailty. These observations may help explain why men and women are susceptible to different cardiovascular diseases as they age and why frail older adults are most often affected by these diseases.

Sex Differences in Heart Failure

Heart failure (HF) represents a global pandemic health problem with a high impact on health-care costs, affecting about 26 million adults worldwide. The overall HF prevalence and incidence are ~2% and ~0.2% per year, respectively, in Western countries, with half of the HF population with reduced ejection fraction (HFpEF) and half with preserved (HFpEF) or mid-range ejection fraction (HFmrEF). Sex differences may exist in HF. More males have HFrEF or HFmrEF and an ischemic etiology, whereas more females have HFpEF and hypertension, diastolic dysfunction, and valvular pathologies as HF etiologies. Females are generally older, have a higher EF, higher frequency of HF-related symptoms, and lower NYHA functional status. Generally, it is observed that female HF patients tend to have more comorbidities such as atrial fibrillation, diabetes, hypertension, anemia, iron deficiency, renal disease, arthritis, frailty, depression, and thyroid abnormalities. However, overall, females have better prognosis in terms of mortality and hospitalization risk compared with men, regardless of EF. Potential sex differences in HF characteristics may be underestimated because of the underrepresentation of females in cardiovascular research and, in particular, the sex imbalance in clinical trial enrollment may avoid to identify sex-specific differences in treatments' benefit.

Acute exposure to progesterone attenuates cardiac contraction by modifying myofilament calcium sensitivity in the female mouse heart

Acute application of progesterone attenuates cardiac contraction, although the underlying mechanisms are unclear. We investigated whether progesterone modified contraction in isolated ventricular myocytes and identified the Ca²⁺ handling mechanisms involved in female C57BL/6 mice (6-9 mo; sodium pentobarbital anesthesia). Cells were field-stimulated (4 Hz; 37°C) and exposed to progesterone (0.001-10.0 μM) or vehicle (35 min). Ca²⁺ transients (fura-2) and cell shortening were recorded simultaneously. Maximal concentrations of progesterone inhibited peak contraction by 71.4% (IC₅₀ = 160 ± 50 nM; n = 12) and slowed relaxation by 75.4%. By contrast, progesterone had no effect on amplitudes or time courses of underlying Ca²⁺ transients. Progesterone (1 µM) also abbreviated action potential duration. When the duration of depolarization was controlled by voltage-clamp, progesterone attenuated contraction and slowed relaxation but did not affect Ca²⁺ currents, Ca²⁺ transients, sarcoplasmic reticulum (SR) content, or fractional release of SR Ca²⁺ Actomyosin MgATPase activity was assayed in myofilaments from hearts perfused with progesterone (1 μM) or vehicle (35 min). While maximal responses to Ca²⁺ were not affected by progesterone, myofilament Ca²⁺ sensitivity was reduced (EC₅₀ = 0.94 ± 0.01 µM for control, n = 7 vs. 1.13 ± 0.05 μM for progesterone, n = 6; P < 0.05) and progesterone increased phosphorylation of myosin binding protein C. The effects on contraction were inhibited by lonaprisan (progesterone receptor antagonist) and levosimendan (Ca²⁺ sensitizer). Unlike results in females, progesterone had no effect on contraction or myofilament Ca²⁺ sensitivity in age-matched male mice. These data indicate that progesterone reduces myofilament Ca²⁺ sensitivity in female hearts, which may exacerbate manifestations of cardiovascular disease late in pregnancy when progesterone levels are high.

NEW & NOTEWORTHY

We investigated myocardial effects of acute application of progesterone. In females, but not males, progesterone attenuates and slows cardiomyocyte contraction with no effect on calcium transients. Progesterone also reduces myofilament calcium sensitivity in female hearts. This may adversely affect heart function, especially when serum progesterone levels are high in pregnancy.Listen to this article's corresponding podcast at https://ajpheart.podbean.com/e/acute-progesterone-modifies-cardiac-contraction/.

Arterial Remodeling in B-Type Natriuretic Peptide Knock-Out Females

Sexual dimorphisms are recognized in cardiovascular conditions such as hypertension, stroke, thrombosis and vasculitis. B-type natriuretic peptide (BNP) is a guanylyl cyclase A (GC-A) agonist. The anti-hypertensive, vasodilatory, anti-fibrotic, and anti-hypertrophic properties of BNP are well established in male animal models. Although circulating BNP levels are higher in women, when compared to age-matched men, the cardiovascular protective propensity of BNP in females is poorly understood. We assessed the cardiovascular consequences of BNP deletion in genetically null (Nppb−/−) female rat lines. Throughout the study, blood pressure (BP) remained uninfluenced by genotype, and cardiorenal consequences of BNP knock out remained minor. Unexpectedly, approximately 60% of Nppb−/− females developed mesenteric polyarteritis-nodosa (PAN)-like vasculitis in their life span, some as early as 4 months of age. Mesenteric lesions involved intense arterial remodeling, progressive inflammation, occluded lumens, and less frequently intestinal necrosis and multiple visceral arterial aneurysms. Cumulative pathologies resulted in a significant decline in survival of the Nppb−/− female. This study highlights BNP’s vasoprotective propensity, bringing to light a possible sex specific difference in the cardiovascular protection provided by BNP. Defects in the BNP/GC-A/cGMP pathway may play a role in arteriopathies in women, while GC-A agonists may provide effective therapy for arteritis.

Focused Cardiovascular Care for Women: The Need and Role in Clinical Practice

Over the past decade, an emerging clinical research focus on cardiovascular (CV) disease (CVD) risk in women has highlighted sex-specific factors that are uniquely important in the prevention and early detection of coronary atherosclerosis in women. Concurrently, a 30% decrease in the number of female deaths from CVD has been observed. Despite this, CVD continues to be the leading cause of death in women, outnumbering deaths from all other causes combined. Clinical practice approaches that focus on the unique aspects of CV care for women are needed to provide necessary resources for the prevention, diagnosis, and treatment of CVD in women. In addition to increasing opportunities for women to participate in CV research, Women's Heart Clinics offer unique settings in which to deliver comprehensive CV care and education, ensuring appropriate diagnostic testing, while monitoring effectiveness of treatment. This article reviews the emerging need and role of focused CV care to address sex-specific aspects of diagnosis and treatment of CVD in women.

Women-specific factors to consider in risk, diagnosis and treatment of cardiovascular disease

In the era of individualized medicine, gaps in knowledge remain about sex-specific risk factors, diagnostic and treatment options that might reduce mortality from cardiovascular disease (CVD) and improve outcomes for both women and men. In this review, contributions of biological mechanisms involving the sex chromosomes and the sex hormones on the cardiovascular system will be discussed in relationship to the female-specific risk factors for CVD: hypertensive disorders of pregnancy, menopause and use of hormonal therapies for contraception and menopausal symptoms. Additionally, sex-specific factors to consider in the differential diagnosis and treatment of four prevalent CVDs (hypertension, stroke, coronary artery disease and congestive heart failure) will be reviewed with emphasis on areas where additional research is needed.

Functional impact of diaphragm muscle sarcopenia in both male and female mice

To perform a range of ventilatory and nonventilatory behaviors, the diaphragm muscle (DIAm) must be able to generate sufficient forces throughout the lifespan. We hypothesized that sarcopenia impacts DIAm force generation and thus limits performance of expulsive, higher force, nonventilatory behaviors. Male and female mice (n = 79) at 6 and 24 mo of age (100 vs. 70-75% survival, respectively) were used to examine transdiaphragmatic pressure (Pdi) generation across motor behaviors in vivo and in vitro DIAm specific force. We found a significant effect of age on maximum Pdi (20-41% decline during tracheal occlusion and bilateral phrenic nerve stimulation), maximum DIAm specific force (30% decline), and DIAm fatigue resistance (15% increase). There were no differences between sexes in these age effects on DIAm performance. These results support our hypothesis that sarcopenia primarily impacts higher force, nonventilatory motor behaviors of the DIAm. Such functional limitations may have negative implications in the ability of the DIAm to generate forces needed for airway clearance in old age and thereby contribute to age-related respiratory complications.

Sex- and gender-specific research priorities for the emergency management of heart failure and acute arrhythmia: proceedings from the 2014 Academic Emergency Medicine Consensus Conference Cardiovascular Research Workgroup

The emergency department (ED) is the point of first contact for patients with acute heart failure and arrhythmias, with 1 million annual ED visits in the United States. Although the total numbers of men and women living with heart failure are similar, female patients are underrepresented in clinical studies, with current knowledge predominantly based on data from male patients. This has led to an underappreciation of the sex-specific differences in clinical characteristics and pathophysiology-based management of heart failure. Similar disparities have been found in management of acute arrhythmias, especially atrial arrhythmias that lead to an increased risk of stroke in women. Additionally, peripartum and postpartum cardiomyopathy represent a diagnostic and treatment dilemma. This article is the result of a breakout session in the cardiovascular and resuscitation work group of the 2014 Academic Emergency Medicine consensus conference "Gender-Specific Research in Emergency Medicine: Investigate, Understand, and Translate How Gender Affects Patient Outcomes." A nominal group technique was used to identify and prioritize themes and research questions using electronic mail, monthly conference calls, in-person meetings, and Web-based surveys between June 2013 and May 2014. Consensus was achieved through three rounds of nomination followed by the meeting on May 13, 2014, and resulted in seven priority themes that are essential to the common complex clinical syndrome of heart failure for both men and women and include the areas of pathophysiology; presentation and symptomatology; and diagnostic strategies using biomarkers, treatment, and mortality, with special consideration to arrhythmia management and pregnancy.

Sex, drugs, and trial design: sex influences the heart and drug responses

Preclinical studies indicate that the phosphodiesterase 5 (PDE5) inhibitor sildenafil is protective against hypertrophy-induced cardiac remodeling. Despite an initial clinical study demonstrating sildenafil-dependent amelioration of pathological remodeling, the cardioprotective effect of this drug was not significant in a large placebo-controlled clinical trail. In this issue, Sasaki and colleagues reveal that the efficacy of PDE5 inhibition in female mice requires estrogen. Induction of cardiac stress in male and intact female mice resulted in increased activation of protein kinase G (PKG) signaling, which was further enhanced by sildenafil. PKG activity was not enhanced in ovariectomized (OVX) female mice as a result of cardiac stress, but administration of estrogen restored PKG activation and enhancement by sildenafil. These data highlight the importance of considering sex-specific differences and drug responses in clinical trial design.