INTRODUCTION:In hypertrophic cardiomyopathy (HCM), atrial fibrillation (AF) has historically been regarded to have a deleterious impact on clinical course, strongly associated with progressive heart failure (HF) symptoms. However, there is a paucity of information regarding the impact of AF on HCM employing validated quality of life (QoL) surveys. Therefore, we evaluated the impact of AF on QoL utilizing patient reported outcome measures (PROMs). METHODS:218 consecutive HCM patients with or without AF at the Lahey HCM center in 2022 completed PROMs at their most recent visit evaluating HF (Kansas City Cardiomyopathy Questionnaire [KCCQ]) and AF symptoms (AF Effect on QoL [AFEQT]). RESULTS:Among the 218 patients, 50 (23%) had a history of AF and comprise the primary study cohort. AF was diagnosed at 55 ± 10 years of age, median of 5.5 years before PROM, with 66% of patients treated with a rhythm control strategy with antiarrhythmic drug and/or AF ablation. AFEQT indicated that 52% of patients experienced no or minimal AF-related disability, mild to moderate in 22%, and severe in 26%. There was no substantial difference in HCM phenotype in patients with no or minimal AF disability compared to those with severe disability. HF symptoms for most HCM patients with prior AF history was consistent with no or minimal (59%) or only mild (27%) disability as measured by KCCQ overall summary scores. In addition, with multivariate analysis, AF history was associated with less HF symptoms and improved QoL (OR 0.4, p = 0.02). CONCLUSION:In contrast to prior perceptions, HCM patients with prior AF history were less likely to incur HF symptoms impairing QoL compared to HCM patients without AF. After treatment, prior history of AF did not substantially impact current QoL. These data provide a realistic appraisal for the impact that AF has on HCM patients and also offers a measure of reassurance for this patient subgroup.

There is a significant amount of pressure in EP labs across the country to maximize lab efficiency. Elective pulmonary vein isolation (PVI) and left atrial appendage occlusion (LAAO) devices such as Watchman are being scheduled out several months at most centers. To that end, we have sought to reduce the amount of repeat procedures in select patients by combining cryo PVI ablation with LAAO device implant. This is also beneficial from a patient satisfaction perspective and a safety perspective (e.g.

Intracellular cargos are often membrane-enclosed and transported by microtubule-based motors in the presence of microtubule-associated proteins (MAPs). Whereas increasing evidence reveals how MAPs impact the interactions between motors and microtubules, critical questions remain about the impact of the cargo membrane on transport. Here we combined in vitro optical trapping with theoretical approaches to determine the effect of a lipid cargo membrane on kinesin-based transport in the presence of MAP tau. Our results demonstrate that attaching kinesin to a fluid lipid membrane reduces the inhibitory effect of tau on kinesin. Moreover, adding cholesterol, which reduces kinesin diffusion in the cargo membrane, amplifies the inhibitory effect of tau on kinesin binding in a dosage-dependent manner. We propose that reduction of kinesin diffusion in the cargo membrane underlies the effect of cholesterol on kinesin binding in the presence of tau, and we provide a simple model for this proposed mechanism. Our study establishes a direct link between cargo membrane cholesterol and MAP-based regulation of kinesin-1. The cholesterol effects uncovered here may more broadly extend to other lipid alterations that impact motor diffusion in the cargo membrane, including those associated with aging and neurological diseases.

In hypertrophic cardiomyopathy (HCM) atrial fibrillation (AF) has been historically described as unrelenting, a driver for heart failure, with a decisive impact on quality of life. AF treatment has been deemed less effective in HCM due to high rates of AF recurrence. However, AF has predominantly been characterized from physicians perspective and there is no data on impact on patient reported outcome measures (PROMs).

Intracellular cargos are often membrane-bound and transported by microtubule-based motors in the presence of microtubule-associated proteins (MAPs). Whereas increasing evidence reveals how MAPs impact the interactions between motors and microtubules, critical questions remain about the impact of the cargo membrane on transport. Here we combined in vitro optical trapping with theoretical approaches to determine the effect of a lipid cargo membrane on kinesin-based transport in the presence of MAP tau. Attaching kinesins to a fluid lipid membrane decreases the inhibitory effect of tau in comparison to membrane-free cargos. Adding cholesterol, which reduces kinesin diffusion in the cargo membrane, amplifies the inhibitory effect of tau on kinesin in a dosage-dependent manner. Our findings can be understood in a framework in which kinesin diffusion in the cargo membrane counteracts binding-site occlusion by tau. Our study establishes a direct link between the physical properties of cargo membrane and MAP-based regulation of kinesin-1.

The slow conduction (SC) area in perimitral flutter (PMLF) is not well defined but often is not in the mitral isthmus where ablation is typically performed. We characterized the SC area in reentrant circuits of PMFL and investigated the role of the SC area as a target for ablation. We included 24 patients (age 70 ± 7, 20 male) with PMFL mapped with the Rhythmia high-density mapping system (Boston Scientific). PMFL was defined as a continuous and uninterrupted wavefront circulating along the mitral annulus with total conduction time equal to tachycardia cycle length (TCL). SC zone was defined as narrowing of isochronal line intervals of >60% on a color-coded isochronal map, where each color represented 10% of TCL. Scar was defined as voltage <0.1 mV. We also identified three types of SC area according to structural and functional aspects: closed type as classic isthmus bordered by electrically silent tissue, epicardial type as a short gap of absent electrical activity in otherwise continuous reentrant circuit, and open type as all others. All 24 reentrant circuits in PMFL contained at least one or two SC areas (total 43, mean 1.8). The SC area was observed in the anterior wall (17, 40%), lateral wall (13, 30%), septum (10, 23%), and posterior wall (3, 7%). Open type SC area was most common (25, 58%), with 11 (26%) closed type, and 7 (16%) epicardial type. The open type was predominantly in the anterior wall (13/25, 52%), the closed type was in the lateral wall (5/11, 45%), and the epicardial type also in the lateral wall (7/7, 100%). Percentage conduction slowing relative to the remainder of the circuit was similar in open and closed type (89% in both), and slightly less in the epicardial type (76%). In 21/24 PMFL, the SC area(s) was targeted for ablation and all 21 PMFLs were successfully terminated when ablation was delivered near or in the SC area (8 open type, 9 closed type, and 4 epicardial type). The presence of SC area was seen in all PMFL. Ablation targeting the SC zone may be a promising ablation strategy and more efficient than purely anatomically-based mitral isthmus ablation.

Perimitral flutter (PMFL) with additional attached loops has not been well described. We characterized PMFL with multiple loops and identified leading and subsidiary circuits within each tachycardia. Between 2016 and 2020, 24 patients were diagnosed with PMFL using the Rhythmia high-density mapping system (Boston Scientific). This study included 13 PMFL patients (age 71 ± 8, 11 male) with multiple reentrant loops on the activation map. A single leading loop was defined when ablation in a single loop terminated tachycardia directly to sinus rhythm. Multiple leading loops were defined when ablation in more than one loop was required to restore sinus rhythm. Double loops were observed in 9 patients and triple loops in 4. The average TCL was 270 ms in PMFL with double loops and 227 ms in those with triple loops. In 9 PMFL with double loops, co-loops were found traversing left PVs (n=5), anterior wall (n=3; Fig.1A), and right PVs (n=1). In 4 PMFL with triple loops, co-loops were found around left PVs (n=3; Fig.1B), LSPV (n=3; Fig.1B), anterior wall (n =1), and RSPV (n =1). We found that in 9 (6 double, 3 triple loops) of 13, PMFL was terminated with ablation in a single loop, confirming “single leading loop” and in 2 of 13, ablation converted PMFL to a different tachycardia, suggesting “multiple leading loops''. Two tachycardias were undetermined due to failed ablation (n=1) and successful ablation at the shared pathway (n=1). When multiple loops co-exist in PMFL they may be dominant or subsidiary. Successful ablation targeting only a single loop suggests that many of these additional loops are subsidiary, and not critical to maintaining tachycardia.

Motor protein-based transport underlies all eukaryotic cell function and survival; dysfunctions are implicated in many diseases including neurodegeneration. Whereas motor proteins have been extensively studied both in vivo and in vitro, many important questions remain. Chief among these is whether and how the composition of the cargo membrane impacts transport. To address this question, we combined advances in membrane biophysics with established single-molecule optical-trapping assays to characterize the transport of membrane-enclosed cargos in vitro. Our study employed the major microtubule-based kinesin-1 motor and tau, an important microtubule-associated protein (MAP). Tau sterically hinders the binding of individual kinesins to the microtubule and significantly inhibits kinesin-based transport of membrane-free cargos. Remarkably, we found that coupling kinesins via a biomimetic membrane reduces the inhibitory effect of tau, significantly enhancing the transport of membrane-enclosed cargos on tau-decorated microtubules. Further, adding cholesterol to the cargo membrane amplifies the inhibitory effect of tau on kinesin. Combing simulation and modeling approaches, we found that cholesterol hinders the ability of individual motors to search for available binding sites on the microtubule (on-rate), thereby amplifying tau's steric inhibition of transport. Our study establishes a direct link between cargo-membrane composition and MAP-based regulation of kinesin-1. The combination of experimental and theoretical approaches we developed is generally applicable for interrogating the regulation of motor proteins in a context directly relevant to in vivo scenarios.

IL-33 is an alarmin required for resistance to the parasite Toxoplasma gondii, but its role in innate resistance to this infection is unclear. T. gondii infection promotes increased stromal cell expression of IL-33 and levels of parasite replication correlate with IL-33 release. In response to infection, a subset of innate lymphoid cells (ILC) emerges composed of IL-33R+ NK cells and ILC1s. In Rag-/- mice, where NK cells and ILC1 provide an innate mechanism of resistance to T. gondii, the loss of IL-33R reduced ILC responses and increased parasite replication. Furthermore, administration of IL-33 to Rag-/- mice resulted in a marked decrease in parasite burden, increased production of IFN-γ and the recruitment and expansion of inflammatory monocytes associated with parasite control. These protective effects of exogenous IL-33 were dependent on endogenous IL-12p40 and the ability of IL-33 to enhance ILC production of IFN-γ. These results highlight that IL-33 synergizes with IL-12 to promote ILC-mediated resistance to T. gondii.

Testing people without symptoms for SARS-CoV-2 followed by isolation of those who test positive could mitigate the covid-19 epidemic pending arrival of an effective vaccine. Key questions for such programs are who should be tested, how often, and when should such testing stop. Answers to these questions depend on test and population characteristics. A cost-effectiveness model that provides answers depending on user-adjustable parameter values is described. Key parameters are the value ascribed to preventing a death and the reproduction number (roughly, rate of spread) at the time surveillance testing is initiated. For current rates of spread, cost-effectiveness usually requires a value per life saved greater than $100,000 and depends critically on the extent and frequency of testing.

Innate lymphoid cells (ILCs) are lymphocytes with critical roles in homeostasis, inflammation, and immunity to pathogens. ILCs are rare relative to other immune cell populations and are primarily defined by lack of expression of markers associated with other immune cell lineages and are predominantly found in mucosal tissues like the gut, lung and skin. They are classified into distinct subsets, ILC1, ILC2, and ILC3, which mirror subsets of CD4+ helper T cells. ILC subsets have distinct cytokine and transcription factor profiles which align with their biological functions, although recently it has emerged that ILC subsets are not phenotypically fixed and exhibit considerable heterogeneity and plasticity in different contexts. Here, we describe protocols for the maintenance, expansion, and induction of plasticity in mouse and human ILC2s. The resulting cells can be used for molecular interrogation of ILC function and biology, both in vivo and in vitro.

We present the case of a 57-year-old man with a primary prevention internal cardioverter-defibrillator for severe nonischemic cardiomyopathy. At the time of elective replacement indicator, systolic function had fully recovered, and his generator was not changed. Nearly 5 years post–elective replacement indicator he received appropriate internal cardioverter-defibrillator therapies during a myocardial infarction. (Level of Difficulty: Intermediate.)