The past 3 decades have been characterized by an exponential growth in knowledge and advances in the clinical treatment of atrial fibrillation (AF). It is now known that AF genesis requires a ...vulnerable atrial substrate and that the formation and composition of this substrate may vary depending on comorbid conditions, genetics, sex, and other factors. Population-based studies have identified numerous factors that modify the atrial substrate and increase AF susceptibility. To date, genetic studies have reported 17 independent signals for AF at 14 genomic regions. Studies have established that advanced age, male sex, and European ancestry are prominent AF risk factors. Other modifiable risk factors include sedentary lifestyle, smoking, obesity, diabetes mellitus, obstructive sleep apnea, and elevated blood pressure predispose to AF, and each factor has been shown to induce structural and electric remodeling of the atria. Both heart failure and myocardial infarction increase risk of AF and vice versa creating a feed-forward loop that increases mortality. Other cardiovascular outcomes attributed to AF, including stroke and thromboembolism, are well established, and epidemiology studies have championed therapeutics that mitigate these adverse outcomes. However, the role of anticoagulation for preventing dementia attributed to AF is less established. Our review is a comprehensive examination of the epidemiological data associating unmodifiable and modifiable risk factors for AF and of the pathophysiological evidence supporting the mechanistic link between each risk factor and AF genesis. Our review also critically examines the epidemiological data on clinical outcomes attributed to AF and summarizes current evidence linking each outcome with AF.
The efficacy of cardiac resynchronization therapy (CRT) depends on placement of the left ventricular lead within the late-activated territory. The geographic extent and 3-dimensional distribution of ...left ventricular (LV) locations yielding optimal CRT remain unknown.
Normal or tachypacing-induced failing canine hearts made dyssynchronous by right ventricular free wall pacing or chronic left bundle-branch ablation were acutely instrumented with a nonconstraining epicardial elastic sock containing 128 electrodes interfaced with a computer-controlled stimulation/recording system. Biventricular CRT was performed using a fixed right ventricular site and randomly selected LV sites covering the entire free wall. For each LV site, global cardiac function (conductance catheter) and mechanical synchrony (magnetic resonance imaging tagging) were determined to yield 3-dimensional maps reflecting CRT impact. Optimal CRT was achieved from LV lateral wall sites, slightly more anterior than posterior and more apical than basal. LV sites yielding > or = 70% of the maximal dP/dtmax increase covered approximately 43% of the LV free wall. This distribution and size were similar in both normal and failing hearts. The region was similar for various systolic and diastolic parameters and correlated with 3-dimensional maps based on mechanical synchrony from magnetic resonance imaging strain analysis.
In hearts with delayed lateral contraction, optimized CRT is achieved over a fairly broad area of LV lateral wall in both nonfailing and failing hearts, with modest anterior or posterior deviation still capable of providing effective CRT. Sites selected to achieve the most mechanical synchrony are generally similar to those that most improve global function, confirming a key assumption underlying the use of wall motion analysis to optimize CRT.
Subcutaneous implantable cardioverter defibrillators (S‐ICDs) provide reliable defibrillation and have enhanced supraventricular tachycardia discrimination and fewer infection rates compared with ...traditional transvenous systems. However, inappropriate shocks remain a frequent problem. Herein, we review the various mechanisms of these inappropriate therapies, some of which are unique to S‐ICDs, and propose an algorithm for preventing recurrences. Proper screening of preimplants is essential to help minimize inappropriate therapies, but patients with hypertrophic cardiomyopathy, Brugada syndrome, and arrhythmogenic right ventricular cardiomyopathy are at particular risk and may require additional measures.
Cardiac Magnetic Resonance Assessment of Dyssynchrony and Myocardial Scar Predicts Function Class Improvement Following Cardiac Resynchronization Therapy Kenneth C. Bilchick, Veronica Dimaano, ...Katherine C. Wu, Robert H. Helm, Robert G. Weiss, Joao A. Lima, Ronald D. Berger, Gordon F. Tomaselli, David A. Bluemke, Henry R. Halperin, Theodore Abraham, David A. Kass, Albert C. Lardo There remains a significant nonresponse rate to cardiac resynchronization therapy (CRT), with recent data also questioning the reproducibility of standard echocardiography-based dyssynchrony metrics. A circumferential mechanical dyssynchrony index (circumferential uniformity ratio estimate CURE) derived from cardiac magnetic resonance (CMR) myocardial tagging was tested for predicting clinical function class improvement following CRT. The CURE index predicted improved functional class in CRT patients with 90% accuracy (positive predictive value: 87%; negative predictive value: 100%). Adding late gadolinium-enhanced data improved accuracy further. Combined CMR tagging and late enhancement data offers promise in the prediction of functional improvement after CRT. As pointed out by Dr. Gorcsan in the accompanying editorial, further studies in larger prospective cohorts will be useful to confirm these findings.
Cognitive impairment is strongly associated with atrial fibrillation (AF). Rate and rhythm control are the two treatment strategies for AF and the effect of treatment strategy on risk of cognitive ...decline and frailty is not well established. We sought to determine how treatment strategy affects geriatric-centered outcomes.
The Systematic Assessment of Geriatric Elements-AF (SAGE-AF) was a prospective, observational, cohort study. Older adults with AF were prospectively enrolled between 2016 and 2018 and followed longitudinally for 2 years. In a non-randomized fashion, participants were grouped by rate or rhythm control treatment strategy based on clinical treatment at enrollment. Baseline characteristics were compared. Longitudinal binary mixed models were used to compare treatment strategy with respect to change in cognitive function and frailty status. Cognitive function and frailty status were assessed with the Montreal Cognitive Assessment Battery and Fried frailty phenotype tools.
972 participants (mean age = 75, SD = 6.8; 49% female, 87% non-Hispanic white) completed baseline examination and 2-year follow-up. 408 (42%) were treated with rate control and 564 (58%) with rhythm control. The patient characteristics of the two groups were different at baseline. Participants in the rate control group were older, more likely to have persistent AF, prior stroke, be treated with warfarin and have baseline cognitive impairment. After adjusting for baseline differences, participants treated with rate control were 1.5 times more likely to be cognitively impaired over 2 years (adjusted OR: 1.47, 95% CI:1.12, 1.98) and had a greater decline in cognitive function (adjusted estimate: -0.59 (0.23), p < 0.01) in comparison to rhythm control. Frailty did not vary between the treatment strategies.
Among those who had 2-year follow-up in non-randomized observational cohort, the decision to rate control AF in older adults was associated with increased odds of decline in cognitive function but not frailty.
Most prior studies on the prognostic significance of newly-diagnosed atrial fibrillation (AF) in COVID-19 did not differentiate newly-diagnosed AF from pre-existing AF. To determine the association ...between newly-diagnosed AF and in-hospital and 30-day mortality among regular users of Veterans Health Administration using data linked to Medicare. We identified Veterans aged ≥ 65 years who were hospitalized for ≥ 24 h with COVID-19 from 06/01/2020 to 1/31/2022 and had ≥ 2 primary care visits within 24 months prior to the index hospitalization. We performed multivariable logistic regression analyses to estimate adjusted risks, risk differences (RD), and odds ratios (OR) for the association between newly-diagnosed AF and the mortality outcomes adjusting for patient demographics, baseline comorbidities, and presence of acute organ dysfunction on admission. Of 23,299 patients in the study cohort, 5.3% had newly-diagnosed AF, and 29.2% had pre-existing AF. In newly-diagnosed AF adjusted in-hospital and 30-day mortality were 16.5% and 22.7%, respectively. Newly-diagnosed AF was associated with increased mortality compared to pre-existing AF (in-hospital: OR 2.02, 95% confidence interval CI 1.72-2.37; RD 7.58%, 95% CI 5.54-9.62) (30-day: OR 1.86; 95% CI 1.60-2.16; RD 9.04%, 95% CI 6.61-11.5) or no AF (in-hospital: OR 2.24, 95% CI 1.93-2.60; RD 8.40%, 95% CI 6.44-10.4) (30-day: 2.07, 95% CI 1.80-2.37; RD 10.2%, 95% CI 7.89-12.6). There was a smaller association between pre-existing AF and the mortality outcomes. Newly-diagnosed AF is an important prognostic marker for patients hospitalized with COVID-19. Whether prevention or treatment of AF improves clinical outcomes in these patients remains unknown.
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