Objectives The aim of this study was to examine the effect of continuous positive airway pressure (CPAP) therapy on atrial fibrillation (AF) recurrence in patients with obstructive sleep apnea (OSA) ...undergoing pulmonary vein isolation (PVI). Background OSA is a predictor of AF recurrence following PVI. However, the impact of CPAP therapy on PVI outcome in patients with OSA is poorly known. Methods Among 426 patients who underwent PVI between 2007 and 2010, 62 patients had a polysomnography-confirmed diagnosis of OSA. While 32 patients were “CPAP users” the remaining 30 patients were “CPAP nonusers.” The recurrence of any atrial tachyarrhythmia, use of antiarrhythmic drugs, and need for repeat ablations were compared between the groups during a follow-up period of 12 months. Additionally, the outcome of patients with OSA was compared to a group of patients from the same PVI cohort without OSA. Results CPAP therapy resulted in higher AF-free survival rate (71.9% vs. 36.7%; p = 0.01) and AF-free survival off antiarrhythmic drugs or repeat ablation following PVI (65.6% vs. 33.3%; p = 0.02). AF recurrence rate of CPAP-treated patients was similar to a group of patients without OSA (HR: 0.7, p = 0.46). AF recurrence following PVI in CPAP nonuser patients was significantly higher (HR: 2.4, p < 0.02) and similar to that of OSA patients managed medically without ablation (HR: 2.1, p = 0.68). Conclusions CPAP is an important therapy in OSA patients undergoing PVI that improves arrhythmia free survival. PVI offers limited value to OSA patients not treated with CPAP.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
BACKGROUND:In vivo description of ventricular tachycardia (VT) circuits is limited by insufficient spatiotemporal resolution. We used a novel high-resolution mapping technology to characterize the ...electrophysiological properties of the postinfarction reentrant VT circuit.
METHODS:In 15 swine, myocardial infarction was induced by left anterior descending artery balloon occlusion. Animals were studied 6 to 8 weeks after myocardial infarction. Activation mapping of VTs was performed by using the Rhythmia mapping system. Activation time was based on a combination of bipolar and unipolar electrograms. The response to overdrive pacing from different zones of the circuit was examined.
RESULTS:A total of 56 monomorphic VTs were induced (3.8±2.1 per animal). Among these, 21 (37.5%) were hemodynamically stable and allowed mapping of the circuit. Isthmuses were 16.4±7.2 mm long and 7.4±2.8 mm wide. Conduction velocities were slowest at the inward curvature into the isthmus entrance (0.28±0.2 m/s), slightly faster at the outward curvature exit (0.40±0.3 m/s) and nearly normal at the central isthmus (0.62±0.2 m/s). In 3 animals, 2 VT morphologies with opposite axes sharing the same isthmus were mapped. Conduction velocities within the shared isthmus were dependent on the activation vector, consistently slower at the proximal curvature. Overdrive pacing from isthmus sites determined by activation mapping was consistent with entrainment criteria for isthmus. However, dimensions of the isthmus defined by entrainment exceeded dimensions of the isthmus measured by activation mapping by 32±18%.
CONCLUSIONS:In postinfarction reentrant VT, conduction velocities are slowest at the proximal and distal curvatures. Entrainment mapping overestimates the true size of the isthmus. High-resolution activation mapping of VT may better guide ablation therapy.
Introduction
PV reconnection is often the result of catheter instability and tissue edema. High‐power short‐duration (HP‐SD) ablation strategies have been shown to improve atrial linear continuity in ...acute pre‐clinical models. This study compares the safety, efficacy, and long‐term durability of HP‐SD ablation with conventional ablation.
Methods and results
In 6 swine, 2 ablation lines were performed anterior and posterior to the crista terminalis, in the smooth and trabeculated right atrium, respectively; and the right superior PV was isolated. In 3 swine, ablation was performed using conventional parameters (Thermocool‐Smarttouch® SF; 30 W/30 seconds) and in 3 other swine using HP‐SD parameters (QDOT‐MICRO™, 90 W/4 seconds). After 30 days, linear integrity was examined by voltage mapping and pacing, and the heart and surrounding tissues were examined by histopathology. Acute line integrity was achieved with both ablation strategies; however, HP‐SD ablation required 80% less RF time compared with conventional ablation (P ≤ 0.01 for all lines). Chronic line integrity was higher with HP‐SD ablation: all 3 posterior lines were continuous and transmural compared to only 1 line created by conventional ablation. In the trabeculated tissue, HP‐SD ablation lesions were wider and of similar depth with 1 of 3 lines being continuous compared to 0 of 3 using conventional ablation. Chronic PVI without stenosis was evident in both groups. There were no steam‐pops. Pleural markings were present in both strategies, but parenchymal lung injury was only evident with conventional ablation.
Conclusions
HP‐SD ablation strategy results in improved linear continuity, shorter ablation time, and a safety profile comparable to conventional ablation.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK, VSZLJ
The American Heart Association, in conjunction with the National Institutes of Health, annually reports the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk ...factors, including core health behaviors (smoking, physical activity, diet, and weight) and health factors (cholesterol, blood pressure, and glucose control) that contribute to cardiovascular health. The Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, congenital heart disease, rhythm disorders, subclinical atherosclerosis, coronary heart disease, heart failure, valvular disease, venous disease, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).
The American Heart Association, through its Epidemiology and Prevention Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States to provide the most current information available in the annual Statistical Update with review of published literature through the year before writing. The 2023 Statistical Update is the product of a full year's worth of effort in 2022 by dedicated volunteer clinicians and scientists, committed government professionals, and American Heart Association staff members. The American Heart Association strives to further understand and help heal health problems inflicted by structural racism, a public health crisis that can significantly damage physical and mental health and perpetuate disparities in access to health care, education, income, housing, and several other factors vital to healthy lives. This year's edition includes additional COVID-19 (coronavirus disease 2019) publications, as well as data on the monitoring and benefits of cardiovascular health in the population, with an enhanced focus on health equity across several key domains.
Each of the chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.
The Statistical Update represents a critical resource for the lay public, policymakers, media professionals, clinicians, health care administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.
The American Heart Association, in conjunction with the National Institutes of Health, annually reports the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk ...factors, including core health behaviors (smoking, physical activity, diet, and weight) and health factors (cholesterol, blood pressure, and glucose control) that contribute to cardiovascular health. The Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, congenital heart disease, rhythm disorders, subclinical atherosclerosis, coronary heart disease, heart failure, valvular disease, venous disease, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).
The American Heart Association, through its Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States to provide the most current information available in the annual Statistical Update. The 2022 Statistical Update is the product of a full year's worth of effort by dedicated volunteer clinicians and scientists, committed government professionals, and American Heart Association staff members. This year's edition includes data on the monitoring and benefits of cardiovascular health in the population and an enhanced focus on social determinants of health, adverse pregnancy outcomes, vascular contributions to brain health, and the global burden of cardiovascular disease and healthy life expectancy.
Each of the chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.
The Statistical Update represents a critical resource for the lay public, policymakers, media professionals, clinicians, health care administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.
BACKGROUNDRadiofrequency ablation using irrigated catheters is performed using a power-controlled mode. However, lesion size is dependent on current delivery at a particular impedance, such that a ...power value alone may not reflect actual energy delivery, resulting in lesion size variability at similar power settings. We hypothesized that modulating baseline impedance at fixed power settings affects ablation lesion dimensions.
METHODSIn 20 ex vivo swine hearts, radiofrequency ablation was performed using an irrigated catheter at a fixed power setting of 30 W per 20 seconds and a multistepped impedance load (100–210Ω). In 4 in vivo thigh muscle preparations and right atria, ablation was performed using similar power settings at 3 baseline impedanceslow (90–130Ω), intermediate (131–180Ω), and high (181–224Ω). The relationship between baseline impedance, current, and lesion dimensions was examined.
RESULTSBaseline impedance had a strong negative correlation with current squared (I) for all experimental modelsex vivo (R=−0.94; P<0.0001), thigh muscle (R=−0.93; P<0.0001), and right atria (R=−0.94; P<0.0001). Lesion dimensions at similar power settings were highly variable and directly related to I (width R=0.853, depth R=0.814). In the thigh muscle, lesion depth was 8.2±0.7, 6.5±0.8, and 4.2±0.5 mm for low, intermediate, and high impedance, respectively (P<0.0001). In right atria lines, low baseline impedance resulted in wider lines (7.2±1.4 mm) relative to intermediate (5.8±1.8 mm) and high impedance (4.7±1.7 mm; P<0.0001).
CONCLUSIONSRadiofrequency ablation in a power control mode results in variable lesion dimensions that are partially related to differences in baseline impedance and current output. Ablation at a lower baseline impedance results in increased current output and lesion dimensions.
Patients with acute MI and an ejection fraction of 35% or less were randomly assigned to receive a wearable cardioverter–defibrillator plus medical therapy or medical therapy alone. At 90 days, there ...was no significant between-group difference in the rate of arrhythmic death.
Abstract At this time, we find ourselves with an abundance of guidelines for management of patients with manifest ventricular tachyarrhythmias, or at risk for such arrhythmias, in patients with ...coronary heart disease (CHD). The guidelines are focused primarily on the “appropriate use” of the implantable cardioverter/defibrillator (ICD). Unfortunately, the bulk of the guidelines have very little basis in the underlying pathophysiology responsible for sudden cardiac death (SCD) in patients with CHD. Rather, they are based primarily on the results of randomized clinical trials that merely sought to take broad populations at elevated total mortality risk and determining whether the ICD can reduce overall mortality. The trials were not aimed at elucidating or exploiting the varying pathophysiology responsible for the ventricular arrhythmias responsible for most sudden deaths in this setting. The goal of the trials is appropriate – to improve the survival. The problem with promoting trials that solely determine whether a broad-based population (identified by one parameter such as ejection fraction that bears no direct relation to the pathogenesis of arrhythmias) derives a survival benefit from a therapy such as the ICD, is that many patients that could benefit from the ICD are missed (not covered by the guidelines), and many patients that will never benefit from the ICD are exposed to its risks and costs. How can we advance the use of potent, but expensive therapies that carry risk such as the ICD to improve survival of patients with CHD today? There are several avenues worth pursuing, both for short-term as well as long-term gain. First, there are several models shown to have the potential to identify patients currently covered by the guidelines for ICD use, that are highly unlikely to benefit, because of the existing co-morbidities. These models are likely to be valid because there is significant overlap in the parameters identified in each model, and they have been tested retrospectively in a variety of study populations. These models are not likely to be incorporated into use guidelines, until they have been tested prospectively in a randomized trial in a contemporary patient population. This can, and should be done. Use of such a model, based on noninvasive, readily available clinical markers offers the possibility of improving the efficiency with which ICDs are used to reduce the risk of SCD in CHD patients. Second, we need to recognize the fact that SCD in this population is a result of multiple potential mechanisms. And, the electrophysiologic substrates underlying these mechanisms are influenced by interactions with the autonomic nervous system and hemodynamic conditions. While most out-of-hospital cardiac arrests do not occur in persons with overt heart failure, the presence of heart failure clearly increases the risk for SCD, likely by a variety of mechanisms. There is increasing evidence that altered left ventricular geometry may not only reduce LV mechanical efficiency, but may also have direct effects on the electrophysiologic substrate. Although there is an abundance of evidence supporting the importance of autonomic interactions in the genesis of spontaneous arrhythmias, the utility of prospectively measuring autonomic indices to predict future arrhythmic events has to date not proven to be useful. Of course, that is not to discount the significant impact of beta-adrenergic blockade on survival and reducing arrhythmic events. Future works must focus more on both animal models of post-infarction arrhythmias, as well as integrating findings from such studies into human physiology, with subsequent testing in the form of randomized clinical trials.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Human ventricular tachycardia (VT) after myocardial infarction usually occurs because of subendocardial reentrant circuits originating in scar tissue that borders surviving myocardial bundles. ...Several preclinical large animal models have been used to further study postinfarct reentrant VT, but with varied experimental methodologies and limited evaluation of the underlying substrate or induced arrhythmia mechanism.
We aimed to develop and characterize a swine model of scar-related reentrant VT.
Thirty-five Yorkshire swine underwent 180-minute occlusion of the left anterior descending coronary artery. Thirty-one animals (89%) survived the 6-8-week survival period. These animals underwent cardiac magnetic resonance imaging followed by electrophysiology study, detailed electroanatomic mapping, and histopathological analysis.
Left ventricular (LV) ejection fraction measured using CMR imaging was 36% ± 6.6% with anteroseptal wall motion abnormality and late gadolinium enhancement across 12.5% ± 4.1% of the LV surface area. Low voltage measured using endocardial electroanatomic mapping encompassed 11.1% ± 3.5% of the LV surface area (bipolar voltage ≤1.5 mV) with anterior, anteroseptal, and anterolateral involvement. Reentrant circuits mapped were largely determined by functional rather than fix anatomical barriers, consistent with "pseudo-block" due to anisotropic conduction. Sustained monomorphic VT was induced in 28 of 31 swine (90%) (67 VTs; 2.4 ± 1.1; range 1-4) and characterized as reentry. VT circuits were subendocardial, with an arrhythmogenic substrate characterized by transmural anterior scar with varying degrees of fibrosis and myocardial fiber disarray on the septal and lateral borders.
This is a well-characterized swine model of scar-related subendocardial reentrant VT. This model can serve as the basis for further investigation in the physiology and therapeutics of humanlike postinfarction reentrant VT.
Sudden cardiac death (SCD) accounts for ∼50% of mortality after myocardial infarction (MI). Most SCDs result from ventricular tachyarrhythmias, and the tachycardias that precipitate cardiac arrest ...result from multiple mechanisms. As a result, it is highly unlikely that any single test will identify all patients at risk for SCD. Current guidelines for use of implantable cardioverter-defibrillators (ICDs) to prevent SCD are based primarily on measurement of left ventricular ejection fraction (LVEF). Although reduced LVEF is associated with increased total cardiac mortality after MI, the focus of current guidelines on LVEF omits ∼50% of patients who die suddenly. In addition, there is no evidence of a mechanistic link between reduced LVEF and arrhythmias. Thus, LVEF is neither sensitive nor specific as a tool for post-MI risk stratification. Newer tests to screen for predisposition to ventricular arrhythmias and SCD examine abnormalities of ventricular repolarization, autonomic nervous system function, and electrical heterogeneity. These tests, as well as older methods such as programmed stimulation, the signal-averaged electrocardiogram, and spontaneous ventricular ectopy, do not perform well in patients with LVEF ≤30%. Recent observational studies suggest, however, that these tests may have greater utility in patients with LVEF >30%. Because SCD results from multiple mechanisms, it is likely that combinations of risk factors will prove more precise for risk stratification. Prospective trials that evaluate the performance of risk stratification schema to determine ICD use are necessary for cost-effective reduction of the incidence of SCD after MI.
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