Sex Differences in Electrophysiology, Ventricular Tachyarrhythmia, Cardiac Arrest and Sudden Cardiac Death Following Acute Myocardial Infarction

Sex Differences in Ventricular Arrhythmias and Adverse Outcomes Following Acute Myocardial Infarction

Background

Ventricular arrhythmias (VAs) are a common cause of death in patients with acute myocardial infarction (AMI). Studies have shown sex differences in the incidence, presentation, and outcomes of AMI. However, less is known about sex differences in patients with AMI who develop VAs.

Objectives

The authors assessed sex differences in incidence and in-hospital outcomes of patients with AMI and VAs.

Methods

Using the National Inpatient Sample 2016 to 2020, we conducted a retrospective analysis of patients admitted for AMI with a secondary diagnosis of VAs. Multivariable logistic regression was performed to estimate the sex-specific differences in the rates and in-hospital outcomes of VAs post-AMI.

Results

We identified 1,543,140 patients admitted with AMI. Of these, (11.3%) 174,565 patients had VAs after AMI. The odds of VAs after AMI were higher among men (12.6% vs 8.8% adjusted odds ratio [AOR]: 1.72; CI: 1.67-1.78; P < 0.001). Women had significantly higher odds of in-hospital mortality (AOR: 1.32; CI: 1.21-1.42; P < 0.001), cardiogenic shock (AOR: 1.08; CI: 1.01-1.15; P < 0.022), and cardiac arrest (AOR: 1.11; CI: 1.03-1.18; P < 0.002). Women were less likely to receive an implantable cardioverter-defibrillator (ICD) (AOR: 0.57; CI: 0.47-0.68; P < 0.001) or undergo catheter ablation (AOR: 0.51; CI: 0.27-0.98; P < 0.001) during the index admission.

Conclusions

We found important sex differences in the incidence and outcomes of VAs among patients with AMI. Women had lower odds of VAs but worse hospital outcomes overall. In addition, women were less likely to receive ICD. Further studies to address these sex disparities are needed.

Influence of standard modifiable risk factors on ventricular tachycardia after myocardial infarction

Background

Inducible ventricular tachycardia (VT) at electrophysiology study (EPS) predicts sudden cardiac death because of ventricular tachyarrhythmia, the single greatest cause of death within 2 years after myocardial infarction (MI).

Objectives

We aimed to assess the association between standard modifiable risk factors (SMuRFs) and inducible VT at EPS early after MI.

Methods

Consecutive patients with left ventricle ejection fraction ≤40% on days 3-5 after ST elevation MI (STEMI) who underwent EPS were prospectively recruited. Positive EPS was defined as induced sustained monomorphic VT cycle length ≥200 ms for ≥10 s or shorter if hemodynamically compromised. The primary outcome was inducibility of VT at EPS, and the secondary outcome was all-cause mortality on follow-up.

Results

In 410 eligible patients undergoing EPS soon (median of 9 days) after STEMI, 126 had inducible VT. Ex-smokers experienced an increased risk of inducible VT [multivariable logistic regression adjusted odds ratio (OR) 2.0, p = 0.033] compared with current or never-smokers, with comparable risk. The presence of any SMuRFs apart from being a current smoker conferred an increased risk of inducible VT (adjusted OR 1.9, p = 0.043). Neither the number of SMuRFs nor the presence of any SMuRFs was associated with mortality at a median follow-up of 5.4 years.

Conclusions

In patients with recent STEMI and impaired left ventricular function, the presence of any SMuRFs, apart from being a current smoker, conferred an increased risk of inducible VT at EPS. These results highlight the need to modify SMuRFs in this high-risk subset of patients.

Impact of sex on clinical, procedural characteristics and outcomes of catheter ablation for ventricular arrhythmias according to underlying heart disease

BACKGROUND

Women are under-represented in many key studies and trials examining outcomes of catheter ablation (CA) for ventricular arrhythmias (VA). We compared characteristics between men and women undergoing their first catheter ablation for VA at a single centre over 10 years.

METHODS

The clinical, procedural characteristics and outcomes of 287 consecutive patients (male = 182, female = 105), undergoing their first CA at our centre over 10 years were compared according to sex and underlying heart disease.

RESULTS

In the ablation population, women were younger, had fewer co-morbidities, were less likely to have ischemic cardiomyopathy (ICM) and VA storm and were more likely to have idiopathic VA and premature ventricular complexes as the indication for ablation (P < 0.05 for all). Amongst idiopathic and non-ischemic cardiomyopathy (NICM) subgroups, baseline characteristics were similar; amongst ICM, women were younger and had higher numbers of drug failure pre-ablation (P = 0.05). Women were similar to men in all procedural characteristics, acute procedural success and complications, regardless of underlying heart disease. At median follow-up of 666 days, VA-free survival, overall mortality and survival free of death or transplant were comparable in both groups. Sex was not a predictor of these outcomes, after accounting for clinical and procedural characteristics.

CONCLUSION

Women represented 36% of the real-world population at our centre referred for CA of VA. There are key differences in clinical features of women versus men referred for VA ablation. Despite these differences, VA ablation in women can be accomplished with similar success and complication rates to men, regardless of underlying heart disease.

Factors predicting cardiac arrest in acute coronary syndrome patients under 50: a state-wide angiographic and forensic evaluation of outcomes

BACKGROUND

An uncertain proportion of patients with acute coronary syndrome (ACS) also experience out-of-hospital cardiac arrest (OHCA). Predictors of OHCA in ACS remain unclear and vulnerable to selection bias as pre-hospital deceased patients are usually not included.

METHODS

Data on patients aged 18-50 years from a percutaneous coronary intervention (PCI) and OHCA registry were combined to identify all patients experiencing OHCA due to ACS (not including those managed medically or who proceeded to cardiac surgery). Clinical, angiographic and forensic details were collated. In-hospital and post-discharge outcomes were compared between OHCA survivors and non-OHCA ACS patients.

RESULTS

OHCA occurred in 6.0% of ACS patients transported to hospital and 10.0% of all ACS patients. Clinical predictors were non-diabetic status (p=0.015), non-obesity (p=0.004), ST-elevation myocardial infarction (p<0.0001) and left main (p<0.0002) or left anterior descending (LAD) coronary artery (p<0.0001) as culprit vessel. OHCA patients had poorer in-hospital clinical outcomes, including longer length of stay and higher pre-procedural intubation, cardiogenic shock, major adverse cardiovascular events, bleeding, and mortality (p<0.0001 for all). At 30 days, OHCA survivors had equivalent cardiac function and return to premorbid independence but higher rates of anxiety/depression (p=0.029).

CONCLUSION

OHCA complicates approximately 10% of ACS in the young. Predictors of OHCA are being non-diabetic, non-obese, having a STEMI presentation, and left main or LAD coronary culprit lesion. For OHCA patients surviving to PCI, higher rates of in-hospital complications are observed. Despite this, recovery of pre-morbid physical and cardiac function is equivalent to non-OHCA patients, apart from higher rates of anxiety/depression.

Comparison of Frequency of Ventricular Tachyarrhythmia in Men-Versus-Women in Patients with Implantable Cardioverter-Defibrillator for Primary Prevention

Current guidelines do not account for possible sex differences in the risk of ventricular tachyarrhythmia (VTA). We sought to identify specific factors associated with increased risk for VTA in women implanted with a primary prevention implantable cardioverter-defibrillator (ICD). Our study cohort consisted of 4,506 patients with an ICD or cardiac resynchronization therapy-defibrillator who were enrolled in the 4 landmark MADIT studies - MADIT-II, MADIT-RISK, MADIT-CRT and MADIT-RIT (1,075 women [24%]). Fine and Gray regression models were used to identify female-specific risk factors for the primary end point of VTA, defined as ICD-recorded, treated, or monitored, sustained ventricular tachycardia ≥170 beats per minute or ventricular fibrillation. At 3.5 years of follow-up, the cumulative incidence of VTA was significantly lower in women than men (17% vs 26%, respectively; p <0.001 for the entire follow-up). Use of amiodarone at enrollment, Black race, and history of previous myocardial infarction without previous revascularization was found to be independent risk factors of VTA in women. Of these factors, only Black race was associated with a statistically significant risk increase in men. At 3.5 years, the cumulative incidence of VTA in women with one or more of these risk factors was 27% compared with 14% in women with none of the risk factors (hazard ratio [confidence interval] = 2.08 [1.49 to 2.91]). In conclusion, our study, comprising 4 landmark ICD clinical trials, shows that sex and race have the potential to be used for improved risk stratification of patients who are candidates for primary prevention ICD.

Sex Differences in the Risk of First and Recurrent Ventricular Tachyarrhythmias Among Patients Receiving an Implantable Cardioverter-Defibrillator for Primary Prevention

Importance

Current guidelines for primary implantable cardioverter-defibrillator (ICD) therapy do not account for sex differences in arrhythmic risk in ICD candidates.

Objective

To evaluate the association between sex and risk of ventricular tachyarrhythmia (VTA) and mortality.

Design, Setting, and Participants

This cohort study compared differences in the risk of VTA and mortality between 4506 men and women enrolled in the 4 Multicenter Automatic Defibrillator Implantation Trials (MADIT) between July 1, 1997, and December 31, 2011. Data from prospective randomized controlled multicenter studies were analyzed retrospectively. Men and women with an ICD or cardiac resynchronization therapy defibrillator who were enrolled in all MADIT studies were included. Data were analyzed between January 10 and June 10, 2021.

Exposures

ICD implant.

Main Outcomes and Measures

The primary end point was sustained VTA, defined as ICD-recorded, treated or monitored VTA at least 170/min or ventricular fibrillation. Secondary VTA end points included VTA at least 200/min, appropriate ICD shocks, and appropriate antitachycardia pacing. All end points were included in a first and recurrent event analysis.

Results

Of the 4506 study participants, 3431 were men (76%). Mean (SD) age of the cohort was 64 (12) years. For women vs men, the mean (SD) age (64 [12] years vs 64 [11] years) and left ventricular ejection fraction (24% vs 25%) were similar, but women exhibited a higher frequency of nonischemic cardiomyopathy (454 of 1075 women [42%] vs 2535 of 3431 men [74%]). Women had significantly lower 3-year cumulative probability of sustained VTA (16% vs 26%), fast VTA (9% vs 17%), and appropriate ICD shocks (7% vs 15%) compared with men (P < .001 for all). Multivariable analysis showed that female sex was independently associated with at least 40% lower risk of all first and recurrent VTA end points (P < .001 for all), including the primary end point (first event, HR = 60 [95% CI, 50-73], P < .001; recurrent event, HR = 49 [95% CI, 43-55], P < .001), after accounting for the competing risk of all-cause mortality and nonarrhythmic mortality. The lower VTA risk associated with female sex was consistent in risk subsets but was significantly more pronounced in patients with nonischemic cardiomyopathy (female vs male in the ischemic group: hazard ratio, 0.73 [95% CI, 0.56-0.95], P = .02; nonischemic group: hazard ratio, 0.50 [95% CI, 0.38-0.66], P < .001; P = .03 for interaction between female sex and cardiomyopathy).

Conclusions and Relevance

Findings suggest that women display a significantly lower risk of first and recurrent life-threatening VTA events than men, and that it is more pronounced in patients with nonischemic cardiomyopathy, suggesting a need for sex-specific risk assessment for primary prevention ICD therapy.

Catheter Ablation for Ventricular Tachycardia in Ischaemic Versus Non-Ischaemic Cardiomyopathy: A Systematic Review and Meta-Analysis

BACKGROUND

There are differences in substrate and ablation approaches for ventricular tachycardia (VT) in ischaemic (ICM) and non-ischaemic cardiomyopathy (NICM).

OBJECTIVE

To perform a systematic review and meta-analysis comparing clinical and procedural characteristics/outcomes of VT ablation in ICM versus NICM.

METHODS

Electronic databases were searched for comparative studies reporting outcomes of VT ablation in patients with ICM and NICM. Primary outcomes were acute procedural success, VT recurrence and long-term mortality. Meta-analyses were performed using random-effects modelling.

RESULTS

Thirty-one (31) studies (7,473 patients; 4,418 ICM and 3,055 NICM) were included. Patients with ICM were significantly older (67.0 vs 55.3 yrs), more commonly male (89% vs 79%), had lower left ventricular ejection fraction (29% vs 38%) were less likely to undergo epicardial access (11% vs 36%) and were more likely to require haemodynamic support during ablation (relative risk [RR] 1.30; 95% CI 1.01-1.69). Acute procedural success (i.e. non-inducibility of VT) was higher in the ICM cohort (RR 1.10, 95% CI 1.05-1.15). Recurrence of VT at follow-up was significantly lower in the ICM cohort (RR 0.77; 95% CI 0.70-0.84). Peri-procedural mortality, incidence of procedural complications and long-term mortality were not significantly different between the cohorts.

CONCLUSIONS

NICM and ICM patients undergoing VT ablation are fundamentally different in their clinical characteristics, ablation approaches, acute procedural outcomes and likelihood of VA recurrence. VT ablation in NICM has a lower likelihood of procedural success with increased risk of VA recurrence, consistent with known challenging arrhythmia substrate.

Arrhythmia in Cardiomyopathy: Sex and Gender Differences

PURPOSE OF REVIEW

There is emerging evidence for important sex differences in cardiac arrhythmias. In this up-to-date review, we summarise the differences in incidence, aetiology, treatment and prevention of ventricular arrhythmias (VAs) and sudden cardiac death (SCD) in women versus men, in the context of ischaemic and nonischaemic cardiomyopathies.

RECENT FINDINGS

The incidence of ventricular tachyarrhythmia and SCD is significantly lower in women than in men with ischaemic cardiomyopathy, whereas sex differences in nonischaemic cardiomyopathy are less clear. Women who receive a primary prevention implantable cardioverter-defibrillator (ICD) are less likely to receive appropriate activations, compared to men; however, such findings are limited by under-representation of women. Women with ischaemic cardiomyopathy have significantly lower incidence of VA and SCD compared to men and may not derive the same benefit from a primary prevention ICD. However, further clinical ICD studies are needed that ensure adequate female participation, in order to examine sex differences in outcomes in both ischaemic and nonischaemic cardiomyopathies.

Effect of age and sex on the incidence of ventricular arrhythmia in a rat model of acute ischemia

BACKGROUND

The impact of sex and age on the arrhythmic susceptibility within the setting of acute ischemia is masked by the fact that acute coronary events result from coronary artery disease appearing with age much earlier among men than among women.

METHODS AND RESULTS

LAD ligation or sham operations were performed in rats of both sexes at the age 3 and 24 months. An ECG was recorded continuously for 6 h after the operation. The number of early and late premature ventricular beats (PVBs), episodes of ventricular tachycardia (VT) and fibrillation (VF), heart rate, QRS, QT and Tpeak-Tend duration were analysed. Epicardial action potentials were recorded in vivo, Ca²⁺ signaling was evaluated in isolated cardiomyocytes, fibrosis and connexin-43 expression and localization were measured in the septum. PVBs, VT and VF episodes are much more common in older males than in young males and females independently from their age. Fibrosis with varying intensity in different muscle layers, hypertrophy of cardiomyocytes, reduced number of gap junctions and their appearance on the lateral myocyte membrane, QT prolongation, increase transmural dispersion of repolarisation and a decreased function of SERCA2a may increase the propensity to arrhythmia within the setting of acute ischemia.

CONCLUSION

We show that the male sex, especially in case of older individuals is a strong predictor of increased arrhythmic susceptibility within the acute ischemia setting regardless of its impact on the occurrence of cardiovascular diseases. A personalized sex-dependent prevention treatment is needed to reduce the mortality in acute phases of myocardial infarction.

Higher 1-year mortality in women admitted to intensive care units after cardiac arrest: A nationwide overview from the Netherlands between 2010 and 2018

PURPOSE

We study sex differences in 1-year mortality of out-of-hospital cardiac arrest (OHCA) and in-hospital cardiac arrest (IHCA) patients admitted to the intensive care unit (ICU).

DATA

A retrospective cohort analysis of OHCA and IHCA patients registered in the NICE registry in the Netherlands. The primary and secondary outcomes were 1-year and hospital mortality, respectively.

RESULTS

We included 19,440 OHCA patients (5977 women, 30.7%) and 13,461 IHCA patients (4889 women, 36.3%). For OHCA, 1-year mortality was 63.9% in women and 52.6% in men (Hazard Ratio [HR] 1.28, 95% Confidence Interval [95% CI] 1.23-1.34). For IHCA, 1-year mortality was 60.0% in women and 57.0% in men (HR 1.09, 95% CI 1.04-1.14). In OHCA, hospital mortality was 57.4% in women and 46.5% in men (Odds Ratio [OR] 1.42, 95% CI 1.33-1.52). In IHCA, hospital mortality was 52.0% in women and 48.2% in men (OR 1.11, 95% CI 1.03-1.20).

CONCLUSION

Women admitted to the ICU after cardiac arrest have a higher mortality rate than men. After left-truncation, we found that this sex difference persisted for OHCA. For IHCA we found that the effect of sex was mainly present in the initial phase after the cardiac arrest.

Risk of in-hospital life-threatening ventricular arrhythmia or death after ST-elevation myocardial infarction vs. the Takotsubo syndrome

AIMS

The risk of life-threatening ventricular arrhythmias (LTVA) has been reported to be lower in Takotsubo syndrome (TS) compared with ST-elevation myocardial infarction (STEMI). However, the extent to which these differences relate to the fact that most patients with TS are women (who have a lower risk of LTVA) and a relatively larger proportion of patients with STEMI are men is incompletely understood. We aimed to investigate the risk of LTVA or death in sex-matched and age-matched patients with TS, anterior STEMI, and non-anterior STEMI.

METHODS AND RESULTS

We systematically reviewed the charts of all patients with TS who were treated at Sahlgrenska University Hospital (Gothenburg, Sweden) between 2008 and 2019. A total of 155 patients with confirmed TS (according to the European Society of Cardiology diagnostic criteria for TS) were sex-matched and age-matched 1:1:1 to patients with anterior and non-anterior STEMI. Baseline characteristics and in-hospital outcomes were recorded directly from the patient charts for all patients, and all admission electrocardiographs were analysed. The primary outcome was the composite of death or LTVA [defined as sustained ventricular tachycardia (>30 s) or ventricular fibrillation] within 72 h. The risk of LTVA or death within 72 h after admission was considerably lower in TS (2.6%) vs. anterior STEMI (14%; P = 0.002) and non-anterior STEMI (9.0%; P = 0.02), despite similar or greater risks of acute heart failure, and similar risks of cardiogenic shock. Compared with STEMI, TS was associated with a lower risk of sustained and non-sustained ventricular tachycardia and ventricular fibrillation.

CONCLUSIONS

In a predominantly female age-matched and sex-matched cohort of patients with TS, anterior STEMI, and non-anterior STEMI, the adjusted risk of in-hospital LTVA or death was considerably lower in TS compared with STEMI, despite similar or greater risk of acute heart failure and similar risk of cardiogenic shock.

Spatial distribution of physiologic 12-lead QRS complex

The normal physiologic range of QRS complex duration spans between 80 and 125 ms with known differences between females and males which cannot be explained by the anatomical variations of heart sizes. To investigate the reasons for the sex differences as well as for the wide range of normal values, a technology is proposed based on the singular value decomposition and on the separation of different orthogonal components of the QRS complex. This allows classification of the proportions of different components representing the 3-dimensional representation of the electrocardiographic signal as well as classification of components that go beyond the 3-dimensional representation and that correspond to the degree of intricate convolutions of the depolarisation sequence. The technology was applied to 382,019 individual 10-s ECG samples recorded in 639 healthy subjects (311 females and 328 males) aged 33.8 ± 9.4 years. The analyses showed that QRS duration was mainly influenced by the proportions of the first two orthogonal components of the QRS complex. The first component demonstrated statistically significantly larger proportion of the total QRS power (expressed by the absolute area of the complex in all independent ECG leads) in females than in males (64.2 ± 11.6% vs 59.7 ± 11.9%, p < 0.00001—measured at resting heart rate of 60 beats per minute) while the second component demonstrated larger proportion of the QRS power in males compared to females (33.1 ± 11.9% vs 29.6 ± 11.4%, p < 0.001). The analysis also showed that the components attributable to localised depolarisation sequence abnormalities were significantly larger in males compared to females (2.85 ± 1.08% vs 2.42 ± 0.87%, p < 0.00001). In addition to the demonstration of the technology, the study concludes that the detailed convolution of the depolarisation waveform is individual, and that smoother and less intricate depolarisation propagation is the mechanism likely responsible for shorter QRS duration in females.