Automatic External Defibrillators: the Potential for Widespread Prevention of Sudden Cardiac Death in the Community

The vast majority of witnessed sudden cardiac death is due to the unpredictable occurrence of ventricular fibrillation, which is almost uniformly reversed by the immediate application of defibrillation. Thus, there is dire need for development of the appropriate conditions for early defibrillation in places where the likelihood of an unexpected sudden death event is deemed probable. In this setting, the automatic external defibrillators (AED) in the hands of even trained lay persons has been considered to have the potential to be the single greatest advance in the treatment of cardiac arrest due to ventricular fibrillation since the development of cardiopulmonary resuscitation. Several studies suggest that the use of publicly accessible AEDs by lay persons is feasible and that organized AED training should also focus on community and on-site responders. The potential for widespread prevention of sudden cardiac death in the community with the use of AEDs is discussed in this brief overview

Cardiac Resynchronisation Therapy and Cellular Bioenergetics: Effects Beyond Chamber Mechanics

Cardiac resynchronisation therapy is a cornerstone in the treatment of advanced dyssynchronous heart failure. However, despite its widespread clinical application, precise mechanisms through which it exerts its beneficial effects remain elusive. Several studies have pointed to a metabolic component suggesting that, both in concert with alterations in chamber mechanics and independently of them, resynchronisation reverses detrimental changes to cellular metabolism, increasing energy efficiency and metabolic reserve. These actions could partially account for the existence of responders that improve functionally but not echocardiographically. This article will attempt to summarise key components of cardiomyocyte metabolism in health and heart failure, with a focus on the dyssynchronous variant. Both chamber mechanics-related and -unrelated pathways of resynchronisation effects on bioenergetics – stemming from the ultramicroscopic level – and a possible common underlying mechanism relating mechanosensing to metabolism through the cytoskeleton will be presented. Improved insights regarding the cellular and molecular effects of resynchronisation on bioenergetics will promote our understanding of non-response, optimal device programming and lead to better patient care

Cardiac Resynchronization Therapy and Proarrhythmia: Weathering the Storm

In patients with significant left ventricular (LV) dysfunction and congestive heart failure despite optimal medical therapy, implantation of cardiac resynchronization therapy-defibrillator (CRT-D) devices has been shown to improve symptoms and diminish ventricular tachyarrhythmia susceptibility.We describe the case of a patient with dilated cardiomyopathy who developed ventricular tachycardia storm (VTS) one month after the implantation of a CRT-D device. VTS was initially controlled with pharmacotherapy, allowing the patient to continue with biventricular pacing. Two months later the patient was readmitted due to multiple episodes of polymorphic ventricular tachycardia. VTS was refractory to various intravenous antiarrhythmic drugs and it was finally controlled only when LV pacing was turned off.In patients with heart failure treated with CRT-D, VTS can occur and is best managed by turning off LV pacing. Our report raises an important and concerning issue of biventricular pacing causing ‘proarrhythmia’ in rare instances

Effect of Transient Myocardial Ischemia on QT Interval Dispersion Among Patients with Unstable Angina

Objective: Our aim was to examine the effect of transient myocardial ischemia on QT interval and QT interval dispersion in patients presenting with unstable angina.Methods: We studied 31 patients (mean age 64±10, 22 men, 16 with an old myocardial infarction, 6 with previous coronary bypass surgery) admitted with unstable angina manifestations. Patients with a history of complex ventricular ectopy, malignant ventricular arrhythmias, advanced congestive heart failure or antiarrhythmic drug therapy were excluded. The uncorrected and corrected QT interval and QT dispersion were measured during angina as well as after the relief of pain.Results: The RR intervals were not significantly changed by the ischemic event (879±121 ms at rest to 877±173 ms during angina). However, both the uncorrected and corrected QT intervals were significantly increased during angina (from 410±45 ms and 440±41 ms at rest to 425±53 ms and 460±42 ms during angina respectively, p<0.05 for both). Similarly, both the uncorrected (QTd) and the corrected (QTcd) QT dispersion values were significantly prolonged during ischemia (QTd: 58±23 ms at rest to 83±33 ms during ischemia, p<0.001, QTcd: 63±26 ms at rest to 95±36 ms during ischemia, p<0.001). The observed increment in the QTd and QTcd provoked by ischemia was not different among the unstable angina patients with and without old myocardial infarction.Conclusion: Transient myocardial ischemia besides an increase in the QT and QTc intervals provokes an increase in both the corrected and uncorrected QT interval dispersion. Under certain circumstances, this may contribute to the genesis of serious reentry ventricular arrhythmias

COVID-19 in congenital heart disease (COaCHeD) study

Background: COVID-19 has caused significant worldwide morbidity and mortality. Congenital heart disease (CHD) is likely to increase vulnerability and understanding the predictors of adverse outcomes is key to optimising care.// Objective: Ascertain the impact of COVID-19 on people with CHD and define risk factors for adverse outcomes.// Methods: Multicentre UK study undertaken 1 March 2020–30 June 2021 during the COVID-19 pandemic. Data were collected on CHD diagnoses, clinical presentation and outcomes. Multivariable logistic regression with multiple imputation was performed to explore predictors of death and hospitalisation.// Results: There were 405 reported cases (127 paediatric/278 adult). In children (age <16 years), there were 5 (3.9%) deaths. Adjusted ORs (AORs) for hospitalisation in children were significantly lower with each ascending year of age (OR 0.85, 95% CI 0.75 to 0.96 (p<0.01)). In adults, there were 24 (8.6%) deaths (19 with comorbidities) and 74 (26.6%) hospital admissions. AORs for death in adults were significantly increased with each year of age (OR 1.05, 95% CI 1.01 to 1.10 (p<0.01)) and with pulmonary arterial hypertension (PAH; OR 5.99, 95% CI 1.34 to 26.91 (p=0.02)). AORs for hospitalisation in adults were significantly higher with each additional year of age (OR 1.03, 95% CI 1.00 to 1.05 (p=0.04)), additional comorbidities (OR 3.23, 95% CI 1.31 to 7.97 (p=0.01)) and genetic disease (OR 2.87, 95% CI 1.04 to 7.94 (p=0.04)).// Conclusions: Children were at low risk of death and hospitalisation secondary to COVID-19 even with severe CHD, but hospital admission rates were higher in younger children, independent of comorbidity. In adults, higher likelihood of death was associated with increasing age and PAH, and of hospitalisation with age, comorbidities and genetic disease. An individualised approach, based on age and comorbidities, should be taken to COVID-19 management in patients with CHD

COVID-19 in congenital heart disease (COaCHeD) study

BACKGROUND: COVID-19 has caused significant worldwide morbidity and mortality. Congenital heart disease (CHD) is likely to increase vulnerability and understanding the predictors of adverse outcomes is key to optimising care.OBJECTIVE: Ascertain the impact of COVID-19 on people with CHD and define risk factors for adverse outcomes.METHODS: Multicentre UK study undertaken 1 March 2020-30 June 2021 during the COVID-19 pandemic. Data were collected on CHD diagnoses, clinical presentation and outcomes. Multivariable logistic regression with multiple imputation was performed to explore predictors of death and hospitalisation.RESULTS: There were 405 reported cases (127 paediatric/278 adult). In children (age &lt;16 years), there were 5 (3.9%) deaths. Adjusted ORs (AORs) for hospitalisation in children were significantly lower with each ascending year of age (OR 0.85, 95% CI 0.75 to 0.96 (p&lt;0.01)). In adults, there were 24 (8.6%) deaths (19 with comorbidities) and 74 (26.6%) hospital admissions. AORs for death in adults were significantly increased with each year of age (OR 1.05, 95% CI 1.01 to 1.10 (p&lt;0.01)) and with pulmonary arterial hypertension (PAH; OR 5.99, 95% CI 1.34 to 26.91 (p=0.02)). AORs for hospitalisation in adults were significantly higher with each additional year of age (OR 1.03, 95% CI 1.00 to 1.05 (p=0.04)), additional comorbidities (OR 3.23, 95% CI 1.31 to 7.97 (p=0.01)) and genetic disease (OR 2.87, 95% CI 1.04 to 7.94 (p=0.04)).CONCLUSIONS: Children were at low risk of death and hospitalisation secondary to COVID-19 even with severe CHD, but hospital admission rates were higher in younger children, independent of comorbidity. In adults, higher likelihood of death was associated with increasing age and PAH, and of hospitalisation with age, comorbidities and genetic disease. An individualised approach, based on age and comorbidities, should be taken to COVID-19 management in patients with CHD.</p