Sex Disparities in Sudden Cardiac Death

Understanding the spectrum of cardiovascular risk in women - A primer for prevention

Cardiovascular disease (CVD) is the leading cause of death in women worldwide and the lifetime risk of CVD in women is similar to men. However, the pathophysiology of CVD varies between women and men necessitating a sex-specific understanding of cardiovascular (CV) risk. A belief that women have a lower CVD risk than men, and an underrepresentation in clinical research for many years has led to a paucity of evidence in the prevention and management of CVD in women. Many recent efforts have tried to bridge the gap. As a result, we now know that traditional risk factors impact CVD risk differently in women when compared with men. There are also numerous sex-specific and pregnancy related risk factors that modify the risk and can predict the future development of CVD in women. This is important as risk calculators, in general, tend to misclassify risk in young women with nontraditional CVD risk factors. To address this, guidelines have introduced the concept of risk enhancers that can suggest a higher risk. The use of coronary artery calcium score can further accurately delineate risk in these women, leading to an appropriate matching of therapy to underlying risk. This review discusses implementation strategies that are essential to mitigate disparities in CVD outcomes and optimizing CVD risk in women.

Sex Differences in Outcomes of Patients with an Implantable Cardioverter-Defibrillator for the Secondary Prevention of Sudden Cardiac Death

Background: In patients with an implantable cardioverter-defibrillator (ICD) for secondary prevention, sex differences may exist in clinical outcomes. We sought to investigate sex differences in appropriate ICD therapy, appropriate and inappropriate shock, and all-cause mortality in this patient population. Methods: A total of 257 patients who received an ICD for a secondary prevention indication in the University Medical Centre Groningen (UMCG) between 1 January 2012 and 31 December 2018 were retrospectively included in a consecutive manner. Appropriate ICD therapy, comprising shock and antitachycardia pacing (ATP) for ventricular fibrillation (VF) or ventricular tachycardia (VT), was the primary outcome. Results: The patient population included 257 patients, of whom 45 (18%) were women and 212 (82%) were men. The median of the age was 64 (interquartile range (IQR) 53-72) years. During follow-up (median duration 6.2 (IQR 4.8-7.8) years), first appropriate device therapy took place in 10 (22%) patients for women and 85 (40%) patients for men. Female sex was negatively associated with the rate of appropriate ICD therapy, univariably (hazard ratio (HR) 0.48 [95% confidence interval (CI) 0.25-0.93]; p = 0.030) and multivariably (HR 0.44 [95% CI 0.20-0.95]; p = 0.036). Conclusions: Women with secondary prevention ICDs were less likely than men to receive appropriate ICD therapy.

Role of low-density lipoprotein electronegativity and sexual dimorphism in contributing early ventricular tachyarrhythmias following ST-elevation myocardial infarction

Background

Early ventricular tachycardia/fibrillation (VT/VF) in patients with ST-elevation myocardial infarction (STEMI) has higher morbidity and mortality. This study examines gender-differentiated risk factors and underlying mechanisms for early onset VT/VF in STEMI.

Methods

We analyzed data from 2,964 consecutive STEMI patients between January 1, 2008 and December 31, 2021. Early VT/VF was defined as occurrence of spontaneous VT/VF of ≥30 s or requirement of immediate cardioversion/defibrillation within the first 48 h after symptoms. An ex vivo ischemic-reperfusion experiments were conducted in 8-week-old ApoE-/- mice fed a high-fat diet to explore the underlying mechanisms of early VT/VF.

Results

In 255 of out 2,964 STEMI patients who experienced early VT/VF, the age was younger (58.6 ± 13.8 vs. 61.0 ± 13.0 years old, P = 0.008) with a male predominance. The plasma levels of L5, the most electronegative subclass of low-density lipoprotein, was higher in early VT/VF patients compared to those without early VT/VF (n = 21, L5: 14.1 ± 22.6% vs. n = 46, L5: 4.3 ± 9.9%, P = 0.016). In the experimental setup, all male mice (n = 4) developed VT/VF post sham operation, whereas no such incidence was observed in the female mice (n = 3). Significantly, male mice exhibited considerably slower cardiac conduction velocity as compared to their female counterparts in whole heart preparations (25.01 ± 0.93 cm/s vs.42.32 ± 5.70 cm/s, P < 0.001), despite analogous action potential durations. Furthermore, isolated ventricular myocytes from male mice showed a distinctly lower sodium current density (-29.20 ± 3.04 pA/pF, n = 6) in comparison to female mice (-114.05 ± 6.41 pA/pF, n = 6, P < 0.001). This decreased sodium current density was paralleled by a reduced membrane expression of Nav1.5 protein (0.38 ± 0.06 vs. 0.89 ± 0.09 A.U., P < 0.001) and increased cytosolic Nav1.5 levels (0.59 ± 0.06 vs. 0.29 ± 0.04 A.U., P = 0.001) in male mice. Furthermore, it was observed that the overall expressions of sorting nexin 27 (SNX27) and vacuolar protein sorting 26 (VPS26) were significantly diminished in male mice as compared to female littermates (0.91 ± 0.15 vs. 1.70 ± 0.28, P = 0.02 and 0.74 ± 0.09 vs. 1.57 ± 0.13, P < 0.01, respectively).

Conclusions

Our findings reveal that male STEMI patients with early VT/VF are associated with elevated L5 levels. The gender-based discrepancy in early VT/VF predisposition might be due to compromised sodium channel trafficking, possibly linked with increased LDL electronegativity.

Sex disparities in bystander defibrillation for out-of-hospital cardiac arrest

Background

Previous studies have suggested that females experiencing out-of-hospital cardiac arrest (OHCA) receive lower rates of both bystander cardiopulmonary resuscitation (CPR) and defibrillation compared to males. Whether this disparity has improved over time is unknown.

Methods

A state-wide OHCA registry in Victoria, Australia collected data over twenty years (2002-2021) regarding rates of bystander interventions in OHCA. Characteristics and outcomes of each OHCA were compared with logistic regression according to sex and time (defined in two-year periods).

Results

32,502 OHCAs were included (69.7% male). Both bystander CPR and defibrillation rates increased for females over time (p < 0.0001). There was no sex disparity in receipt of bystander CPR after adjustment for baseline differences. Females were less likely than males to receive bystander defibrillation, with sex disparity increasing from 2010 onwards (adjOR 0.26 (95%CI 0.09-0.80) in 2020-21 for females compared to males).

Conclusion

Initiatives to increase bystander CPR and defibrillation have resulted in higher overall rates of bystander interventions in the last two decades and no significant sex differences in provision of bystander CPR. However, females receive less bystander defibrillation than males, and sex disparity is increasing. Strategies to promote bystander defibrillation in females experiencing OHCA with a shockable rhythm should be a priority.

Current Trends in Biohumoral Screening for the Risk of Sudden Cardiac Death: A Systematic Review

Background and Objectives: Sudden cardiac death (SCD) represents a challenge to health systems globally and is met with increased frequency in the population. Over time, multiple screening methods have been proposed, including the analysis of various plasma biomarkers. This article aims to analyze for illustrative purposes the specialized literature in terms of current biomarkers and testing trends, in the case of cardiovascular diseases and implicitly sudden cardiac death. Materials and Methods: In this regard, we searched the PubMed database from 2010 to the present time using the keywords "sudden cardiac death" and "biomarkers". The inclusion criteria were clinical trials that analyzed the effectiveness of screening methods in terms of biomarkers used in stratifying the risk of cardiac distress and/or sudden cardiac death. We excluded reviews, meta-analyses, and studies looking at the effectiveness of treatments. Results: An extended approach was found, through studies that brought to the forefront both classical markers analyzed by new, more performant methods, markers for other pathologies that also determined cardiovascular impact, non-specific molecules with effects on the cardiovascular system, and state-of-the-art markers, such as microRNA. Some molecules were analyzed simultaneously in certain groups of patients. Conclusion: The observed current trend revealed the tendency to define the clinical-biological particularities of the person to be screened.

Provision of bystander CPR for out-of-hospital cardiac arrest in the Middle East: a retrospective gender-based analysis

BACKGROUND

Previous studies conducted in North America, Europe, and East Asia (Liu et al., EClinicalMedicine 44:101293, 2022; Matsui et al., JAMA Netw Open 2:e195111, 2019; Awad et al., J Am Coll Emerg Physicians Open 4:e12957, 2023; Yoon et al., Prehosp Emerg Care :1-7, 2022) reported gender disparities in the provision of bystander CPR for patients with out-of-hospital cardiac arrest (OHCA). However, it remains unknown whether similar disparities exist in the Middle Eastern and Gulf regions. The primary objective of this study is to evaluate gender differences in the provision of bystander CPR for patients with OHCA in Qatar.

METHODS

Retrospective analysis of data obtained from Hamad Medical Corporation OHCA registry in the State of Qatar (2016-2022). We included adults with non-traumatic and EMS-attended OHCA. We used multilevel logistic regression to examine the association between gender and provision of bystander CPR.

RESULTS

In total, 4283 patients were included. Of those, 3414 (79.7%) were males, 1639 (38.3%) arrested in public locations, and 1463 (34.2%) received bystander CPR. Unadjusted comparisons showed that females were significantly older than males (mean age: 62.2 vs. 52.7). Females had a lower proportion of OHCA occurring in public locations (15.1% vs. 44.2%) and a lower proportion of shockable rhythm (11.9 vs. 27.5%). Regarding the outcome variable (provision of bystander CPR), the unadjusted analysis showed that the proportion of females who received bystander CPR was lower than that of males (29.2% vs. 35.4%, p < 0.001). However, after adjustment, we found no significant difference in provision of bystander CPR by gender (adjusted OR female vs. male 0.99, 95% CI 0.84-1.20, p = 0.97). In the subgroup who arrested in public locations, the analysis revealed females had greater odds of receiving bystander CPR (adjusted OR female vs. male 1.47, 95% CI 1.10-1.82, p = 0.04).

CONCLUSIONS

Overall, bystander CPR was less common in female gender; after adjustment for other covariates, including arrest location, we found no significant gender differences in provision of bystander CPR. We also observed that females were found to have a lower incidence of cardiac arrest in public locations. Nevertheless, if females were to experience cardiac arrest in a public location, they would be more likely to receive CPR. Further research is required to explain the observed differences in provision of bystander CPR.

Cardiac Magnetic Resonance as an Etiological Diagnosis Tool in Recovered Sudden Cardiac Death or Unstable Ventricular Arrhythmia Patients

BACKGROUND

Cardiac magnetic resonance (CMR) has an increasing diagnostic relevance in survivors of sudden cardiac death (SCD) or unstable ventricular arrhythmia (UVA) in developed countries.

OBJECTIVE

To evaluate retrospectively the additional role of CMR in a developing country where few resources are available, and should be used more effectively.

METHODS

The study included SCD or UVA survivors admitted between 2009 and 2019 at a tertiary academic institution referred to CMR. Demographic, clinical, and laboratory data were collected from the medical records. CMR images and reports were reviewed and their impact on the final etiological diagnosis was determined. A descriptive analysis was performed and p<0.05 established as significant.

RESULTS

Sixty-four patients, 54.9±15.4 years old, and 42 (71.9%) males. Most events (81.3%) were out of the hospital and ventricular tachycardia was the most common rhythm. Cardiovascular medications were previously used by 55 patients, and beta-blockers were the most used medications (37.5%). Electrocardiogram had electrical inactive areas in 21.9% and all of them had fibrosis at CMR. Mean left ventricular ejection fraction (LVEF) was 44±14%, with 60.9% ≤50% and only 29.7% ≤35%. Late gadolinium enhancement was identified in 71.9%, with a transmural pattern in 43.8%. Chagas cardiomyopathy was the most common etiology (28.1%), followed by ischemic cardiomyopathy (17.2%). Among 26 without a previously identified etiology, CMR could define it (15 patients - 57%).

CONCLUSION

In accordance with previous studies in developed countries, CMR was capable of increasing etiological diagnosis and identifying the arrhythmogenic substrate, allowing better care in half of the underdiagnosed patients.

Sudden Cardiac Death: An Update on Commotio Cordis

Sudden cardiac death (SCD) is one of the leading causes of cardiovascular mortality, and it is caused by a diverse array of conditions. Among these is commotio cordis, a relatively infrequent but still significant cause, often seen in young athletes involved in competitive or recreational sports. It is known to be caused by blunt trauma to the chest wall resulting in life-threatening arrhythmia (typically ventricular fibrillation). The current understanding pertains to blunt trauma to the precordium, with an outcome depending on factors such as the type of stimulus, the force of impact, the qualities of the projectile (shape, size, and density), the site of impact, and the timing of impact in relation to the cardiac cycle. In the management of commotio cordis, a history of preceding blunt chest trauma is usually encountered. Imaging is mostly unremarkable except for ECG, which may show malignant ventricular arrhythmias. Treatment is focused on emergent resuscitation with the advanced cardiac life support protocol algorithm, with extensive workup following the return of spontaneous circulation. In the absence of underlying cardiovascular pathologies, implantable cardiac defibrillator insertion is not beneficial, and patients can even resume physical activity if the workup is unremarkable. Proper follow-up is also key in the management and monitoring of re-entrant ventricular arrhythmias, which are amenable to ablative therapy. Prevention of this condition involves protecting the chest wall against blunt trauma, especially with the use of safety balls and chest protectors in certain high-risk sporting activities.  This study aims to elucidate the current epidemiology and clinical management of SCD with a particular focus on a rarely explored etiology, commotio cordis.

Sudden Cardiac Death Among Adolescents in the United Kingdom

BACKGROUND

Causes and precipitating factors of sudden cardiac death (SCD) in adolescents are poorly understood.

OBJECTIVES

The authors sought to investigate the etiologies of SCD and their association with physical activity in a large cohort of adolescents.

METHODS

Between 1994 and June 2022, 7,675 cases of SCD were consecutively referred to our national cardiac pathology center; 756 (10%) were adolescents. All cases underwent detailed autopsy evaluation by expert cardiac pathologists. Clinical information was obtained from referring coroners.

RESULTS

A structurally normal heart, indicative of sudden arrhythmic death syndrome was the most common autopsy finding (n = 474; 63%). Myocardial diseases were detected in 163 cases (22%), including arrhythmogenic cardiomyopathy (n = 36; 5%), hypertrophic cardiomyopathy (n = 31; 4%), idiopathic left ventricular hypertrophy (n = 31; 4%), and myocarditis (n = 30; 4%). Coronary artery anomalies were identified in 17 cases (2%). Decedents were competitive athletes in 128 cases (17%), and 159 decedents (21%) died during exercise. Arrhythmogenic cardiomyopathy was diagnosed in 8% of athletes compared with 4% of nonathletes (P = 0.05); coronary artery anomalies were significantly more common in athletes (9% vs 1%; P < 0.001), as well as commotio cordis (5% compared with 1% in nonathletes; P = 0.001). The 3 main comorbidities were asthma (n = 58; 8%), epilepsy (n = 44; 6%), and obesity (n = 40; 5%).

CONCLUSIONS

Sudden arrhythmic death syndrome and myocardial diseases are the most common conditions diagnosed at autopsy in adolescent victims of SCD. Among causes of SCD, arrhythmogenic cardiomyopathy, coronary artery anomalies, and commotio cordis are more common in young athletes than in similar age sedentary individuals.

Sex differences in ventricular arrhythmias epidemiology, risk factors, and mortality in congestive heart failure

BACKGROUND

Female patients are underrepresented in randomized controlled clinical trials and registries of ventricular arrhythmia (VA). Personalized prevention and therapies require an understanding of sex differences in risk factors and prognosis of VA.

OBJECTIVE

We aimed to assess sex differences in the incidence, risk factors, and mortality of VA in congestive heart failure (HF) patients.

METHODS

This study included 10,889 patients (mean [SD] age, 73.8 [13.4] years; 5917 [53.8%] male) with congestive HF, of which 1555 (14.3%) patients developed VA during hospitalization. VA incidence, potential risk factors, and in-hospital mortality were evaluated in both sexes.

RESULTS

Men were more strongly associated with incident VA compared with women (odds ratio [OR]: 2.006, 95% CI: 1.790-2.248, p < 0.001). Thirteen potential predictors, which accounted for 91.0% of the risk of VA in men and 88.2% in women, were included in this study. There were significant interactions by sex in the association between incident VA, atrial fibrillation (AF) (relative risk ratio = 0.730, 95% CI: 0.571-0.933, interaction p = 0.012), and non-ischemic cardiomyopathy (NICM) (relative risk ratio = 1.391, 95% CI: 1.029-1.872, interaction p = 0.030). Congestive HF patients developed with VA had an approximately 1.5-fold risk of in-hospital mortality, which was not affected by sex.

CONCLUSIONS

In congestive HF patients, incident VA was an independent risk factor of in-hospital mortality, and male sex was strongly associated with an increased risk of VA. Awareness of sex differences in the association of AF and NICM with VA may enhance therapeutic decisions, thus improving their clinical outcomes.

Two decades of implantable cardioverter defibrillator implantation and follow-up at a South African referral centre: trends, indications and long-term outcomes in a resource-limited setting

Background

More than two-thirds of cardiovascular deaths occur in low- and middle-income countries. Sudden cardiac deaths (SCD) from ventricular arrhythmias are an important cause of cardiovascular deaths. Implantable cardioverter defibrillators (ICD) are an important therapeutic strategy for detecting and terminating ventricular arrhythmias in patients at risk of SCD. The profile of patients treated with ICDs in South Africa is unknown. Further, with changing lines of evidence, the implantation trends are undetermined. The objectives of this study were to determine the profile of ICD recipients and implantation trends in a South African quaternary hospital.

Methods

This was a retrospective review of all patients implanted with ICDs at Groote Schuur Hospital from 01 January 1998 to 31 December 2020. A standardised data collection form was used to collect baseline demographic data, information on clinical presentation and ICD follow-up data for the history of ICD shock therapies.

Results

A total of 253 ICDs were implanted; 75% for secondary prevention and 25% for primary prevention. 67.2% of the implanted ICDs were single-chamber ICDs, dual-chamber ICDs were implanted in 12.3% and Cardiac resynchronisation with a defibrillator (CRT-D) in 20.6%. There was an upward trajectory of ICD implantations during the study period. Increasing numbers of dual-chamber devices and CRT-D were implanted over time. ICD recipients had a mean (standard deviation) age of 50 (14) years and were predominantly male (69%). Primary prevention ICD recipients were younger than secondary prevention recipients, with a mean (SD) age of 46 (14) years versus 51 (14) years, p = 0.019. The secondary prevention group presented with ventricular tachycardia in 81%, ventricular fibrillation in 13% and cardiopulmonary resuscitation without documented heart rhythm in 5.3% (10/190). After a median (interquartile range) follow-up of 44 (15; 93) months, there was an overall mortality rate of 16.2%, with no mortality difference between the primary and secondary prevention patient groups.

Conclusion

There is an increase in the annual number of ICDs implanted at a South African referral centre. ICDs are predominantly implanted for secondary prevention. However, over time the number of devices implanted for primary prevention is steadily increased. During follow-up, there was no mortality difference between the primary prevention and the secondary prevention groups.

The DIVERSE Study: Determining the Importance of Various gEnders, Races, and body Shapes for CPR Education using manikins

Certain demographic groups are less likely to receive efficient CPR, and poor representation of these groups in the manikins used for CPR simulation may play a role. The aim of the DIVERSE Study was to survey organizations that teach CPR to determine the demographic characteristics of the manikins they utilize for simulations. Institutions, businesses, and non-governmental organizations which provide CPR certification in North and Latin America were surveyed through a collaboration with the Emerging Leaders group of the Interamerican Society of Cardiology (SIAC). A total of 56 survey responses were received from North America (n=18; 869 total manikins) and Latin America (n=38; 1514 total manikins). Of the total manikins (n=2,383), 12% were non-white, 6% represented women, <1% represented a non-lean body habitus, and 1% represented pregnant individuals. Despite the importance of diverse manikin representation in simulation training, diverse representation is lacking in manikins used in North and Latin America.