Too Little of a Good Thing: Strong Associations Between Cardiac Size and Fitness Among Women

Genetics, Fitness, and Left Ventricular Remodelling: The Current State of Play

Cardiorespiratory fitness (CRF) exists on a spectrum and is driven by a constellation of factors, including genetic and environmental differences. This results in wide interindividual variation in baseline CRF and the ability to improve CRF with regular endurance exercise training. As opposed to monogenic conditions, CRF is described as a complex genetic trait as it is believed to be influenced by multiple common genetic variants in addition to exogenous factors. Importantly, CRF is an independent predictor of morbidity and mortality, and so understanding the impact of genetic variation on CRF may provide insights into both human athletic performance and personalized risk assessment and prevention. Despite rapidly advancing technology, progress in this field has been restricted by small sample sizes and the limited number of genetic studies using the "gold standard" objective measure of peak oxygen consumption (VO2peak) for CRF assessment. In recent years, there has been increasing interest in the heritability of numerous parameters of cardiac structure and function and how this may relate to both normal cardiac physiology and disease pathology. Regular endurance training can result in exercise-induced cardiac remodelling, which manifests as balanced dilation of cardiac chambers and is associated with superior CRF. This results in a complex relationship between CRF, cardiac size, and exercise, and whether shared genetic pathways may influence this remains unknown. In this review we highlight recent and relevant studies into the genomic predictors of CRF with a unique emphasis on how this may relate to cardiac remodelling and human adaptation to endurance exercise.

Left ventricular size and heart failure: A cardiac MRI assessment of 38,129 individuals from the UK Biobank

BACKGROUND

Previous studies suggest that prevalent heart failure (HF) differs based on left ventricular ejection fraction (LVEF) and left ventricular (LV) chamber size. Furthermore, the prevalence of HF with preserved ejection fraction (HFpEF) is often considered approaching, or exceeding that of HF with reduced ejection fraction in the community.

AIM

The aim of this study was to evaluate prevalent and incident HF based on LVEF and CMR-determined LV size within a large community-dwelling cohort.

METHODS

Individuals from the United Kingdom Biobank (UKB) who underwent CMR and had available health record linkage to allow ascertainment of HF diagnosis were included. The cohort was analysed according to LVEF, LV end-diastolic volume (LVEDV) quartiles and LVEDV indexed to body surface area (LVEDVi).

RESULTS

38,129 individuals were included, comprising those with reduced LVEF (LVEF<50 %, n = 5096) and preserved LVEF (LVEF 50-60 %, n = 22,907, LVEF≥60 %, n = 10,126). Prevalent HF was highest in males with LVEF<50 %, and participants with reduced LVEF had higher rates of incident HF (p < 0.001) during the follow-up period (median = 2.46 years from CMR). Mean LVEDV and LVEDVi were largest in individuals with EF < 50 % (146.9 ± 36.2 ml and 76.8 ± 16.4 ml/m2 respectively). Compared to the smallest quartiles, the largest quartiles for LVEDV were associated with increased odds of HF (odds ratio 2.14 [95 % confidence interval 1.47-3.12], p < 0.001).

CONCLUSIONS

Over 50 % of HF cases occur in individuals with LVEF ≥50 %, however HF prevalence is highest in those with reduced LVEF, particularly in males. Larger LV size is associated with increased HF across the LVEF spectrum.

Small Heart Size and Premature Death in 366,484 Individuals With Normal Ejection Fraction

Background

In patients with preserved left ventricular ejection fraction (LVEF), small ventricular size has been associated with reduced functional capacity, but its impact on clinical outcomes is unclear.

Objectives

The goal of this study was to determine the relationship between small heart size and premature mortality within a large multicenter adult patient cohort with transthoracic echocardiographic examinations.

Methods

We divided 366,484 individuals with LVEF ≥50% (including a subset of 279,442 individuals with high-normal LVEF ≥60%) by sex and increasing quartiles for LV end-diastolic volume (LVEDV), LVEDV indexed to body surface area (LVEDVi), and LV end-diastolic diameter to assess associations with 5-year mortality through linkage with the National Death Index.

Results

During approximately 2 million person-years of follow-up, 65,241 deaths occurred. Increasing LV chamber size was associated with reduced odds of 5-year all-cause mortality, particularly for higher LVEF. As compared with the larger quartiles, the smallest cardiac size quartiles were associated with higher 5-year all-cause mortality, even after adjusting for age. The smallest LVEDVi quartile was associated with a 14% to 18% higher odds of 5-year all-cause mortality, with a greater effect with high-normal LVEF. There was a U-shaped relationship between LV chamber size and all-cause mortality. For cardiovascular-related mortality, females in the smallest LVEDVi quartile had a 17% increased odds of mortality, which increased to 30% in those with LVEF ≥60%. In men, there was no significant association between smallest cardiac size and cardiovascular-related mortality.

Conclusions

In individuals with normal LVEF, small ventricular size is associated with increased mortality, particularly among females and those with higher LVEF.

Small Left Ventricular Chamber Size and Mortality in a Large General Population

Enlargement of the left ventricle (LV) is an important marker of adverse cardiac remodeling and poor prognosis. Previous studies demonstrated increased cardiovascular risk in small subsets of patients with a small LV chamber size; however, the prognostic implications of small chamber size in the general population remains unclear. This study aimed to examine the prognosis of a small LV chamber in a large general cohort. All consecutive subjects who underwent echocardiography examinations from 2011 to 2023 were retrieved for analysis. Small chamber size was defined as end-diastolic diameter <42 mm for men and 37.8 mm for women as per American Society of Echocardiography guidelines. The primary end point for the study was all-cause mortality. A total of 46,529 subjects (mean age 60 ± 19 years, 56% men) were included, of whom 3,787 had a small LV chamber size. Clinical variables associated with small chamber included increasing age and lower body surface area. Echocardiographic variables included higher relative wall thickness and E/e' ratio. On the multivariable analysis, the presence of a small LV was significantly associated with mortality (hazard ratio [HR] 1.34, 95% confidence interval [CI] 1.22 to 1.46, p <0.001). This finding was significant in older (over 65 years) (HR 1.30, 95% CI 1.19 to 1.41, p <0.001) and younger (HR 2.09, 95% CI 1.81 to 2.41, p <0.001) subjects and in men and women. In conclusion, in this retrospective large cohort study, small LV chamber size was significantly associated with mortality in a broad range of patients. Further study is necessary to elucidate mechanisms and design preventive strategies.

Left ventricular volume and maximal functional capacity in heart failure with preserved ejection fraction: Size matters

AIMS

Emerging evidence suggests that smaller left ventricular volumes may identify subjects with lower cardiorespiratory fitness. Whether left ventricular size predicts functional capacity in patients with heart failure with preserved ejection fraction (HFpEF) is unclear. This study aimed to explore the association between indexed left ventricular end-diastolic volume (iLVEDV) and maximal functional capacity, assessed by peak oxygen consumption (peakVO2), in stable outpatients with HFpEF.

METHODS AND RESULTS

We prospectively analysed data from 133 consecutive stable outpatients who underwent cardiopulmonary exercise testing and echocardiography on the same day. Data were validated in a cohort of HFpEF patients from San Paolo Hospital, Milan, Italy. A multivariable linear regression assessed the association between iLVEDV and peakVO2. The mean age was 73.2 ± 10.5 years, and 75 (56.4%) were women. The median iLVEDV, indexed left ventricular end-systolic volume, and left ventricular ejection fraction were 46 ml/m2 (30-56), 15 ml/m2 (11-19), and 66% (60-74%), respectively. The median peakVO2 and percentage of predicted peakVO2 were 11 ml/kg/min (9-13) and 64.1% (53-74.4), respectively. Adjusted linear regression analysis showed that smaller iLVEDV was associated with lower peakVO2 (p = 0.0001). In the validation cohort, adjusted linear regression analysis showed a consistent pattern: a smaller iLVEDV was associated with a higher likelihood of reduced peakVO2 (p = 0.004).

CONCLUSIONS

In stable outpatients with HFpEF, a smaller iLVEDV was associated with a lower maximal functional capacity. These findings suggest a need for further studies to understand the pathophysiological mechanisms underlying these observations and to explore targeted treatment strategies for this patient subgroup.

Left Ventricular Volume as a Predictor of Exercise Capacity and Functional Independence in Individuals with Normal Ejection Fraction

AIMS

Low cardiorespiratory fitness (CRF) is associated with functional disability, heart failure and mortality. Left ventricular (LV) end-diastolic volume (LVEDV) has been linked with CRF, but its utility as a diagnostic marker of low CRF has not been tested.

METHODS

This multi-center international cohort examined the relationship between LV size on echocardiography and CRF (peak oxygen uptake [peak VO2] from cardiopulmonary exercise testing) in individuals with LV ejection fraction ≥50%. Absolute and BSA-indexed LVEDV (LVEDVi) were tested as predictors of low CRF and functional disability (peak VO2 <1100ml/min or <18 ml/kg/min) and compared against candidate measures of cardiac structure and function.

RESULTS

2876 individuals (309 endurance athletes, 251 healthy non-athletes, 1969 individuals with unexplained dyspnea, 347 individuals with heart failure with preserved ejection fraction) were included. For the entire cohort, LVEDV had the strongest univariable association with peak VO2 (R2 =0.45, standardized [std]β 0.67, p<0.001) and remained the strongest independent predictor of peak VO2 after adjusting for age, sex and BMI (stdβ 0.30, p<0.001). LVEDV was better at identifying low CRF than most established echocardiographic measures (LVEDV AUC 0.72; LVEDVi AUC 0.71), but equivalent to the E/e' ratio. The probability of achieving a peak VO2 below the functional independence threshold was highest for smaller ventricular volumes, with LVEDV and LVEDVi of 88ml and 57ml/m2 providing the optimal cut-points, respectively.

CONCLUSIONS

Small resting ventricular size is associated with a higher probability of low CRF and functional disability. LV size is the strongest independent echocardiographic predictor of CRF across the health-disease continuum.

Imaging and mechanisms of heart failure with preserved ejection fraction: a state-of-the-art review

Understanding of the pathophysiology of heart failure with preserved ejection fraction (HFpEF) has advanced rapidly over the past two decades. Currently, HFpEF is recognized as a heterogeneous syndrome, and there is a growing movement towards developing personalized treatments based on phenotype-guided strategies. Left ventricular dysfunction is a fundamental pathophysiological abnormality in HFpEF; however, recent evidence also highlights significant roles for the atria, right ventricle, pericardium, and extracardiac contributors. Imaging plays a central role in characterizing these complex and highly integrated domains of pathophysiology. This review focuses on established evidence, recent insights, and the challenges that need to be addressed concerning the pathophysiology of HFpEF, with a focus on imaging-based evaluations and opportunities for further research.

Long-Term Incidence of Bradycardia and Pacemaker Implantations Among Cross-Country Skiers: A Cohort Study

BACKGROUND

Bradycardia is more common among well-trained athletes than in the general population, but the association with pacemaker implantations is less known. We investigated associations of endurance training with incidence of bradycardia and pacemaker implantations, including sex differences and long-term outcome, in a cohort of endurance trained individuals.

METHODS

All Swedish skiers who completed >1 race in the cross-country skiing event Vasaloppet between 1989 and 2011 (n=209 108) and a sample of 532 290 nonskiers were followed until first event of bradycardia, pacemaker implantation, or death, depending on end point. The Swedish National Patient Register was used to obtain diagnoses. Cox regression was used to investigate associations of number of completed races and finishing time in Vasaloppet with incidence of bradycardia and pacemaker implantations. In addition, Cox regression was used to investigate associations of pacemaker implantations with death in skiers and nonskiers.

RESULTS

Male skiers had a higher incidence of bradycardia (adjusted hazard ratio [aHR], 1.19 [95% CI, 1.05-1.34]) and pacemaker implantations (aHR, 1.17 [95% CI, 1.04-1.31]) compared with male nonskiers. Those who completed the most races and had the best performances exhibited the highest incidence. For female skiers in Vasaloppet, the incidence of bradycardia (aHR, 0.98 [95% CI, 0.75-1.30]) and pacemaker implantations (aHR, 0.98 [95% CI, 0.75-1.29]) was not different from that of female nonskiers. The indication for pacemaker differed between skiers and nonskiers, with sick sinus syndrome more common in the former and third-degree atrioventricular block in the latter. Skiers had lower overall mortality rates than nonskiers (aHR, 0.16 [95% CI, 0.15-0.17]). There were no differences in mortality rates by pacemaker status among skiers.

CONCLUSIONS

In this study, male endurance skiers had a higher incidence of bradycardia and pacemaker implantations compared with nonskiers, a pattern not seen in women. Among male skiers, those who completed the most races and had the fastest finishing times had the highest incidence of bradycardia and pacemaker implantations. Within each group, mortality rates did not differ in relation to pacemaker status. These findings suggest that bradycardia associated with training leads to a higher risk for pacemaker implantation without a detrimental effect on mortality risk.

Sex difference in mitral valve prolapse regurgitant volume is resolved by normalization of regurgitant volume to left ventricular end-diastolic volume

Women with primary mitral insufficiency have a smaller regurgitant volume at the same regurgitant fraction than men. We hypothesized that normalizing regurgitant volume with left ventricular end-diastolic volume or allometric scaling would eliminate the difference in regurgitant volume between women and men. The study cohort consisted of 101 patients with mitral valve prolapse undergoing cardiac MRI. Descriptive statistics and linear regression were performed to assess differences between sexes. Of the 101 patients, 46 (46%) were women. Women had a significantly smaller left and right ventricular end-diastolic volume, end-systolic volume, and stroke volume. While there was no difference in regurgitant fraction between women and men (34 ± 13% vs. 35 ± 14%; p = 0.71), women had a significantly smaller regurgitant volume (36 ± 18 ml vs. 49 ± 26 ml; p = 0.005). The slope-intercept relationship between regurgitant fraction and regurgitant volume revealed unique slopes and y-intercept values for men and women (p-value < 0.0001). Normalizing regurgitant volume to left ventricular end-diastolic volume (RVol/LVEDV), body surface area1.5 (RVol/BSA1.5) and height2.7 (RVol/height2.7) all had essentially identical slope-intercept relationships with regurgitant fraction for men and women, but RVol/LVEDV had the smallest effect size. In mitral insufficiency secondary to mitral valve prolapse women have a significantly smaller regurgitant volume than men despite no difference in regurgitant fraction. The significant difference in regurgitant volume between women and men is secondary to women having a smaller left ventricular end-diastolic volume.

Physiological Insights From Asymptomatic Severe Valvular Disease in a Highly Trained Athlete

Parameters relied on as tools for prognostication in valvular disease can be confounded by athletic physiological remodeling. This case describes how cardiopulmonary exercise testing and multimodality imaging may be helpful in assessment of a 46-year-old female athlete with bicuspid aortic valve and subaortic membrane with associated asymptomatic severe mixed aortic valve disease.

Machine Learning-Driven Phenogrouping and Cardiorespiratory Fitness Response in Metastatic Breast Cancer

PURPOSE

The magnitude of cardiorespiratory fitness (CRF) impairment during anticancer treatment and CRF response to aerobic exercise training (AT) are highly variable. The aim of this ancillary analysis was to leverage machine learning approaches to identify patients at high risk of impaired CRF and poor CRF response to AT.

METHODS

We evaluated heterogeneity in CRF among 64 women with metastatic breast cancer randomly assigned to 12 weeks of highly structured AT (n = 33) or control (n = 31). Unsupervised hierarchical cluster analyses were used to identify representative variables from multidimensional prerandomization (baseline) data, and to categorize patients into mutually exclusive subgroups (ie, phenogroups). Logistic and linear regression evaluated the association between phenogroups and impaired CRF (ie, ≤16 mL O2·kg-1·min-1) and CRF response.

RESULTS

Baseline CRF ranged from 10.2 to 38.8 mL O2·kg-1·min-1; CRF response ranged from -15.7 to 4.1 mL O2·kg-1·min-1. Of the n = 120 candidate baseline variables, n = 32 representative variables were identified. Patients were categorized into two phenogroups. Compared with phenogroup 1 (n = 27), phenogroup 2 (n = 37) contained a higher number of patients with none or >three lines of previous anticancer therapy for metastatic disease and had lower resting left ventricular systolic and diastolic function, cardiac output reserve, hematocrit, lymphocyte count, patient-reported outcomes, and CRF (P < .05) at baseline. Among patients allocated to AT (phenogroup 1, n = 12; 44%; phenogroup 2, n = 21; 57%), CRF response (-1.94 ± 3.80 mL O2·kg-1·min-1 v 0.70 ± 2.22 mL O2·kg-1·min-1) was blunted in phenogroup 2 compared with phenogroup 1.

CONCLUSION

Phenotypic clustering identified two subgroups with unique baseline characteristics and CRF outcomes. The identification of CRF phenogroups could help improve cardiovascular risk stratification and guide investigation of targeted exercise interventions among patients with cancer.

Supra-normal and mildly reduced ejection fraction in women -An overlooked vulnerable subpopulation in heart failure

BACKGROUND

Recently, patients with supra-normal left ventricular ejection fraction (snEF) are reported to have high risk of adverse outcomes, especially in women. We sought to evaluate sex-related differences in the association between LVEF and long-term outcomes in heart failure (HF) patients.

METHODS

The multicenter WET-HF Registry enrolled all patients hospitalized for acute decompensated HF (ADHF). We analyzed 3943 patients (age 77 years; 40.1% female) registered from 2006 to 2017. According to LVEF the patients were divided into the 3 groups: HF with reduced EF (HFrEF), mildly reduced EF (HFmrEF) and preserved EF. The primary endpoint was defined as the composite of cardiac death and ADHF rehospitalization after discharge.

RESULTS

In HFmrEF, implementation of guideline-directed medical therapy (GDMT) such as the combination of renin-angiotensin-system inhibitor (RASi) and β-blocker at discharge was significantly lower in women than men even after adjustment for covariates (p = 0.007). There were no such sex-related differences in HFrEF. Female sex was associated with higher incidence of the primary endpoint and ADHF rehospitalization after adjustment for covariates exclusively in HFmrEF. Restricted cubic spline analysis demonstrated a U-shaped relationship between LVEF and the hazard ratio of the primary endpoint showing higher event rate in HFmrEF and HFsnEF in women, but such relationship was not observed in men (p for interaction = 0.037).

CONCLUSIONS

In women, mrEF and snEF were associated with worse long-term outcomes. Additionally, sex-related differences in the GDMT implementation for HFmrEF highlight the need for further exploration, which might lead to creation of sex-specific guidelines to optimize HF management.

The Oxygen Cascade According to HFpEF Likelihood: A Focus on Sex Differences

Background

Women are at greater risk for heart failure with preserved ejection fraction (HFpEF).

Objectives

The aim of the study was to compare sex differences in the pathophysiology of exertional breathlessness in patients with high vs low HFpEF likelihood.

Methods

This cohort study evaluated consecutive patients (n = 1,936) with unexplained dyspnea using cardiopulmonary exercise testing and simultaneous echocardiography and quantified peak oxygen uptake (peak VO2) and its determinants. HFpEF was considered likely when the H2FPEF or HFA-PEFF score was ≥6 or ≥5, respectively. Sex differences were evaluated with the Student's t-test or Mann-Whitney U test and determinants of exercise capacity with a multivariable linear regression.

Results

The cohort included 1,963 patients (49% women and 28% [n = 555] with a high HFpEF likelihood). HFpEF likelihood did not impact the magnitude of sex differences in peak VO2 and its determinants. Overall, women had lower peak VO2 (mean difference -4.4 mL/kg/min [95% CI: -3.7 to -5.1 mL/kg/min]) secondary to a reduced O2 delivery (-0.5 L/min [95% CI: -0.4 to -0.6 L/min]) and less oxygen extraction (-2.9 mL/dL [95% CI: -2.5 to -3.2 mL/dL]). Reduced O2 delivery was due to lower hemoglobin (-1.2 g/dL [95% CI: -0.9 to -1.5 g/dL]) and smaller stroke volume (-15 mL [95% CI: -14 to -17 mL]). Women demonstrated increased mean pulmonary artery pressure/cardiac output slope (+0.5 mm Hg/L/min [95% CI: 0.3-0.7 mm Hg/L/min]) and left ventricular ejection fraction (+1% [95% CI: 1%-2%]), while they had smaller left ventricular end-diastolic volumes (-9 mL/m2 [95% CI: -8 to -11 mL/m2]) and mass (-12 g/m2 [95% CI: -9 to -14 g/m2]) and more often iron deficiency (55% vs 33%; P < 0.001).

Conclusions

Women with unexplained dyspnea had significantly lower peak VO2, regardless of HFpEF likelihood, attributed to both lower peak exercise O2 delivery and extraction. This suggests that physiologic sex differences, and not HFpEF likelihood, are an important factor contributing to functional limitations in females with exertional breathlessness.

Determinants of Impaired Peak Oxygen Uptake in Breast Cancer Survivors: JACC: CardioOncology Primer

•Exercise intolerance is common among breast cancer survivors.•Exercise intolerance in breast cancer survivors is related to cardiac, vascular, and skeletal muscle impairments.•Holistic rehabilitation or pharmacological therapies are needed to address these impairments.

Women's cardiovascular health - the cardio-oncologic jigsaw

Improvements in cancer care have led to an exponential increase in cancer survival. This is particularly the case for breast cancer, where 5-year survival in Australia exceeds 90%. Cardiovascular disease (CVD) has emerged as one of the competing causes of morbidity and mortality among cancer survivors, both as a complication of cancer therapies and because the risk factors for cancer are shared with those for CVD. In this review we cover the key aspects of cardiovascular care for women throughout their cancer journey: the need for baseline cardiovascular risk assessment and management, a crucial component of the cardiovascular care; the importance of long-term surveillance for ongoing maintenance of cardiovascular health; and strong evidence for the beneficial effects of physical exercise to improve both cancer and cardiovascular outcomes. There is general disparity in cardiovascular outcomes for women, which is further exacerbated when both CVD and cancer co-exist. Collaboration between oncology and cardiac services, with an emergence of the whole field of cardio-oncology, allows for expedited investigation and treatment for these patients. This collaboration as well as a holistic approach to patient care and key role of patients' general practitioners are essential to ensure long-term health of people living with, during and beyond cancer.

Atrial septal defect closure in children at young age is beneficial for left ventricular function

Aims

Atrial septal defects (ASDs) lead to volume-loaded right ventricles (RVs). ASD closure does not always alleviate symptoms or improve exercise capacity, which is possibly explained by impaired left ventricular (LV) haemodynamics. This study evaluated the effect of ASD closure in children using non-invasive LV pressure-volume (PV) loops derived from cardiac magnetic resonance (CMR) imaging and brachial blood pressure, compared with controls.

Methods and results

Twenty-three children with ASD underwent CMR, and 17 of them were re-examined 7 (6-9) months after ASD closure. Twelve controls were included. Haemodynamic variables were derived from PV loops by time-resolved LV volumes and brachial blood pressure. After ASD closure, LV volume increased [76 (70-86) vs. 63 (57-70) mL/m2, P = 0.0001]; however, it was still smaller than in controls [76 (70-86) vs. 82 (78-89) mL/m2, P = 0.048]. Compared with controls, children with ASD had higher contractility [2.6 (2.1-3.3) vs. 1.7 (1.5-2.2) mmHg/mL, P = 0.0076] and arterial elastance [2.1 (1.4-3.1) vs. 1.4 (1.2-2.0) mmHg/mL, P = 0.034]. After ASD closure, both contractility [2.0 (1.4-2.5) mmHg/mL, P = 0.0001] and arterial elastance [1.4 (1.3-2.0) mmHg/mL, P = 0.0002] decreased.

Conclusion

Despite the left-to-right atrial shunt that leads to low LV filling and RV enlargement, the LV remains efficient and there is no evidence of impaired LV haemodynamics in children. Closure of ASD at young age while the ventricle is compliant is thus beneficial for LV function. LV volumes, however, remain small after ASD closure, which may impact long-term cardiovascular risk and exercise performance.

Effects of aging and endurance exercise training on cardiorespiratory fitness and cardiac structure and function in healthy midlife and older women

Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality in women in developed societies. Unfavorable structural and functional adaptations within the heart and central blood vessels with sedentary aging in women can act as the substrate for the development of debilitating CVD conditions such as heart failure with preserved ejection fraction (HFpEF). The large decline in cardiorespiratory fitness, as indicated by maximal or peak oxygen uptake (V̇o2max and V̇o2peak, respectively), that occurs in women as they age significantly affects their health and chronic disease status, as well as the risk of cardiovascular and all-cause mortality. Midlife and older women who have performed structured endurance exercise training for several years or decades of their adult lives exhibit a V̇o2max and cardiac and vascular structure and function that are on par or even superior to much younger sedentary women. Therefore, regular endurance exercise training appears to be an effective preventative strategy for mitigating the adverse physiological cardiovascular adaptations associated with sedentary aging in women. Herein, we narratively describe the aging and short- and long-term endurance exercise training adaptations in V̇o2max, cardiac structure, and left ventricular systolic and diastolic function at rest and exercise in midlife and older women. The role of circulating estrogens on cardiac structure and function is described for consideration in the timing of exercise interventions to maximize beneficial adaptations. Current research gaps and potential areas for future investigation to advance our understanding in this critical knowledge area are highlighted.

Understanding Exercise Capacity: From Elite Athlete to HFpEF

Exercise capacity is a spectrum that reflects an individual's functional capacity and the dynamic nature of cardiac remodelling along with respiratory and skeletal muscle systems. The relationship of increasing physical activity, increased cardiac mass and volumes, and improved cardiorespiratory fitness (CRF) is well established in the endurance athlete. However, less emphasis has been placed on the other end of the spectrum, which includes individuals with a more sedentary lifestyle and small hearts who are at increased risk of functional disability and poor clinical outcomes. Reduced CRF is an independent predictor of all-cause mortality and cardiovascular events determined by multiple inter-related exogenous and endogenous factors. In this review, we explore the relationship of physical activity, cardiac remodelling, and CRF across the exercise spectrum, emphasising the critical role of cardiac size in determining exercise capacity. In contrast to the large compliant left ventricle of the endurance athlete, an individual with a lifetime of physical inactivity is likely to have a small, stiff heart with reduced cardiac reserve. We propose that this might contribute to the development of heart failure with preserved ejection fraction in certain individuals, and is key to understanding the link between low CRF and increased risk of heart failure.

A narrative review of heart failure with preserved ejection fraction in breast cancer survivors

Advances in breast cancer (BC) treatment have contributed to improved survival, but BC survivors experience significant short-term and long-term cardiovascular mortality and morbidity, including an elevated risk of heart failure with preserved ejection fraction (HFpEF). Most research has focused on HF with reduced ejection fraction (HFrEF) after BC; however, recent studies suggest HFpEF is the more prevalent subtype after BC and is associated with substantial health burden. The increased HFpEF risk observed in BC survivors may be explained by treatment-related toxicity and by shared risk factors that heighten risk for both BC and HFpEF. Beyond risk factors with physiological impacts that drive HFpEF risk, such as hypertension and obesity, social determinants of health (SDOH) likely contribute to HFpEF risk after BC, impacting diagnosis, management and prognosis.Increasing clinical awareness of HFpEF after BC and screening for cardiovascular (CV) risk factors, in particular hypertension, may be beneficial in this high-risk population. When BC survivors develop HFpEF, treatment focuses on initiating guideline-directed medical therapy and addressing underlying comorbidities with pharmacotherapy or behavioural intervention. HFpEF in BC survivors is understudied. Future directions should focus on improving HFpEF prevention and treatment by building a deeper understanding of HFpEF aetiology and elucidating contributing risk factors and their pathogenesis in HFpEF in BC survivors, in particular the association with different BC treatment modalities, including radiation therapy, chemotherapy, biological therapy and endocrine therapy, for example, aromatase inhibitors. In addition, characterising how SDOH intersect with these therapies is of paramount importance to develop future prevention and management strategies.