Machine learned clusters explain heterogeneity in outcomes from map-guided ablation of Atrial Fibrillation results from the large PROspective STanford AF Registry (ProSTAR)

Background

Several mapping systems are being introduced to guide atrial fibrillation (AF) ablation to patient-specific regions of interest. However, results have been extremely heterogeneous between studies, ranging from very poor to very promising. It is unknown if this reflects specific patient characteristics or procedural factors because most prior series were middle sized (N∼30–100 patients).

Purpose

To study 1 year and 3 year very long-term outcomes from map guided AF-driver ablation in a large patient registry with multiple operators, to identify clinical and procedural features influencing outcomes. In real-world AF patients with diverse comorbidities, we applied a consistent patient-tailored AF mapping and ablation strategy, monitored outcomes carefully and applied statistical and unsupervised machine learning approaches to identify features of success and failure.

Method

We studied 632 consecutive patients (65±10 y, 178 F) undergoing ablation for drug-refractory AF. 59.7% had persistent AF, and 29.9% had prior unsuccessful ablation (median 1 procedure). All patients underwent pulmonary vein isolation (PVI), followed by ablation of AF regions of interest mapped from 64 pole baskets (RhythmView, Abbott, IL), by 11 operators. Patients were followed using ambulatory ECG monitors quarterly for one year, and at the time of symptoms for 3 years.

Results

Fig. 1A shows overall freedom from AF at 1-year of 77.5% (95% CI: 74.2%, 80.9%) and at 3 years of 55.5% (95% CI: 51.2%, 60.1%). Freedom from AF/AT at 1-year was 70.1% (95% CI: 66.5%, 73.8%), and at 3 years was 48.6% (95% CI: 44.3%, 53.3%). Success was higher in patients with procedural termination, first ablation versus prior unsuccessful procedures, for paroxysmal AF than non-paroxysmal AF (1 year: AT/AF freedom 74.9% versus 66.7%, p=0.006), and smaller left atrium. Three clusters (Fig 1B) were identified comprising CHA2DS2VASc score, enlarged LA, prior failed case, presenting rhythm and termination during the procedure (Table 2). At 1 year, freedom from AT/AF was 77.8% (95% CI: 72.2%, 82.1%) for cluster 3 and 56.2% (95% CI: 48.3%, 65.4%) for cluster 1 (Fig. 1B).

Conclusion

In our large registry of N=632 patients undergoing AF-map guided ablations, machine learned clusters identified cohorts with success of 56.2 to 77.8% at 1 year. Future studies should identify if lower success represents technical challenges, such as difficulties in mapping very large atria, or more difficult to treat mechanisms. These results may inform patient inclusion and ablation strategy in upcoming AF treatment trials.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National budget only - NIH, R01 HL149134, R01HL83359

Sleep apnea is associated with stroke in young patients with or without atrial fibrillation:A population study of >2 million individuals

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): NIH, R01 HL149134, R01HL83359

Background

Both Sleep Apnea (SA) and Atrial Fibrillation/flutter (AF) are known risk factors for stroke, and both are increasing in prevalence. They are both under-diagnosed in young adults <60 Y. There is an urgent need to define stroke risk portended by SA and AF yet there a paucity of data in adults aged 20-60 years.

Purpose

To define the relationship between stroke, SA, and AF in a very large cohort of 2 million young-middle aged adults aged 20-60 Y in Northern California.

Methods

We probed the Stanford Research Repository of electronic health data from 01/01/2008 to 11/30/2021 for the diagnoses of stroke, transient ischemic attacks, AF and SA using relevant codes (stroke: 433.X, 434.X, 436.X, I63.X, I65.X, I66.X, G45.X, G46.X; AF: I48.X; SA: G47.X, 327.27).

Results

We identified 2267485 patients aged 20-60Y (55% F; 32% White, 12% Asian, 3% Black), of whom SA was diagnosed in 52730 (2.3%), AF in 10230 (0.4%) and incident stroke in 10385 (0.4%) (Figure 1A)

In patients with SA, 1.5% developed incident stroke. Stroke was more common in patients with SA than those without, regardless of co-existing diagnosis of AF; OR with AF: 1.5 [1.3-1.7, p<0.001] and OR without AF: 3.0 [2.8-3.3 p<0.0001]. Risk of stroke with SA than without was noted to be higher in the younger age subgroups (Figure 1B) regardless of AF.

Although AF was more common in patients with SA than without (odds ratio, OR: 10.1 [9.6-10.6, p<0.0001]), the majority of SA patients (63% with CHADS2VASC ≥2) with stroke did not have a diagnosis of AF (75%), of whom 96% were not anticoagulated (Fig 1, left panel). Of the remaining patients with SA and incident stroke, who did have AF (25%), only 26% were taking OACs at the time of stroke despite median CHADS2 VASC score=3 (Fig 1A, left panel).

Finally, 7% of AF patients developed incident stroke. Of these, 73% had CHADS2VASC ≥2, yet 44% were not anticoagulated. Patients with SA comprised a third of all AF patients with stroke and, compared to AF patients with stroke and without SA, had higher CHADS2VASC (median 3 vs 2, p<0.001) and a similarly low use of anticoagulation (56% vs 54% on OAC) (Fig 1A, right panel).

Conclusions

In >2 million young individuals, we uncover a novel association between SA and incident stroke, regardless of the diagnosis of AF. Surprisingly, three quarters of patients with SA developed incident stroke in the absence of AF, and were not anticoagulated. These results underscore the need to screen for AF and sleep apnea in young adults.

A de novo GRIN1 Variant Associated With Myoclonus and Developmental Delay: From Molecular Mechanism to Rescue Pharmacology

N-Methyl-D-aspartate receptors (NMDARs) are highly expressed in brain and play important roles in neurodevelopment and various neuropathologic conditions. Here, we describe a new phenotype in an individual associated with a novel de novo deleterious variant in GRIN1 (c.1595C>A, p.Pro532His). The clinical phenotype is characterized with developmental encephalopathy, striking stimulus-sensitive myoclonus, and frontal lobe and frontal white matter hypoplasia, with no apparent seizures detected. NMDARs that contained the P532H within the glycine-binding domain of GluN1 with either the GluN2A or GluN2B subunits were evaluated for changes in their pharmacological and biophysical properties, which surprisingly revealed only modest changes in glycine potency but a significant decrease in glutamate potency, an increase in sensitivity to endogenous zinc inhibition, a decrease in response to maximally effective concentrations of agonists, a shortened synaptic-like response time course, a decreased channel open probability, and a reduced receptor cell surface expression. Molecule dynamics simulations suggested that the variant can lead to additional interactions across the dimer interface in the agonist-binding domains, resulting in a more open GluN2 agonist-binding domain cleft, which was also confirmed by single-molecule fluorescence resonance energy transfer measurements. Based on the functional deficits identified, several positive modulators were evaluated to explore potential rescue pharmacology.

Quercetin and Baicalein Act as Potent Antiamyloidogenic and Fibril Destabilizing Agents for SOD1 Fibrils

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that has been associated with the deposition of aggregates of superoxide dismutase 1 (SOD1). Effective therapeutics against SOD1 fibrillation is still an area of active research. Herein, we demonstrate the potential of two naturally occurring flavonoids (quercetin and baicalein) to inhibit fibrillation of wild-type SOD1 with the aid of a series of biophysical techniques. Our seeding experiments reveal that both of these flavonoids significantly affect the fibril elongation. Interestingly, our ThT binding assay, TEM, and SDS-PAGE experiments suggest that these flavonoids also disintegrate the fibrils into shorter fragments but do not completely depolymerize them into monomers. Binding parameters obtained from the analysis of UV-vis spectra suggest that these flavonoids bind moderately to native SOD1 dimer and have different binding sites. Docking of these flavonoids with a non-native monomer, non-native trimer, and oligomer derived from the 11-residue segment of SOD1 indicates that both quercetin and baicalein can bind to these species and thus can arrest the elongation of fibrils by blocking the fibrillar core regions on the intermediate species formed during aggregation of SOD1. MTT assay data revealed that both the flavonoids reduced the cytotoxicity of SOD1 fibrils. Experimental data also show the antiamyloidogenic potential of both flavonoids against A4V SOD1 mutant fibrillation. Thus, our findings may provide a direction for designing effective therapeutic agents against ALS which can act as promising antiamyloidogenic and fibril destabilizing agents.

Effect of pH and temperature on conformational equilibria and aggregation behaviour of curcumin in aqueous binary mixtures of ethanol

Conformational equilibria of curcumin, a potential therapeutic agent, can be modulated by changing pH, temperature and solvent composition.

Curcumin binds to the pre-fibrillar aggregates of Cu/Zn superoxide dismutase (SOD1) and alters its amyloidogenic pathway resulting in reduced cytotoxicity

Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disease that affects motor neurons. Unfortunately, effective therapeutics against this disease is still not available. Almost 20% of familial ALS (fALS) is suggested to be associated with pathological deposition of superoxide dismutase (SOD1). Evidences suggest that SOD1-containing pathological inclusions in ALS exhibit amyloid like properties. An effective strategy to combat ALS may be to inhibit amyloid formation of SOD1 using small molecules. In the present study, we observed the fibrillation of one of the premature forms of SOD1 (SOD1 with reduced disulfide) in the presence of curcumin. Using ThT binding assay, AFM, TEM images and FTIR, we demonstrate that curcumin inhibits the DTT-induced fibrillation of SOD1 and favors the formation of smaller and disordered aggregates of SOD1. The enhancement in curcumin fluorescence on the addition of oligomers and pre-fibrillar aggregates of SOD1 suggests binding of these species to curcumin. Docking studies indicate that putative binding site of curcumin may be the amyloidogenic regions of SOD1. Further, there is a significant increase in SOD1 mediated toxicity in the regime of pre-fibrillar and fibrillar aggregates which is not evident in curcumin containing samples. All these data suggest that curcumin reduces toxicity by binding to the amyloidogenic regions of the species on the aggregation pathway and blocking the formation of the toxic species. Nanoparticles of curcumin with higher aqueous solubility show similar aggregation control as that of curcumin bulk. This suggests a potential role for curcumin in the treatment of ALS.

Multicenter evaluation of individual donor nucleic acid testing (NAT) for simultaneous detection of human immunodeficiency virus -1 & hepatitis B & C viruses in Indian blood donors

BACKGROUND & OBJECTIVE

India has a high prevalence of HIV-1, hapatitis C and B virus (HCV and HBV) in the blood donors but has yet to implement nucleic acid testing (NAT) in blood screening. We undertook a multicentre evaluation of blood donor testing by NAT for simultaneous detection of HIV-1, HBV and HCV in a single tube and also to determine the feasibility of NAT implementation in India's low volume setting.

METHODS

A total of 12,224 unlinked samples along with their serological results were obtained from representative eight blood banks in India and were individually manually tested by the Procleix Ultrio Assay (Chiron Corp. Emeryville, CA) for simultaneous detection of HIV-1, HCV, and HBV.

RESULTS

Of the 12,224 samples tested, 209 (1.71%) were seroreactive. One hundred thirty three samples (1.09%) were reactive by Ultrio assay, 84 samples were seroreactive but NAT non reactive. There were eight NAT yield cases: 1 HIV, 1 HIV-HCV co-infection, and 6 HBV.

INTERPRETATION & CONCLUSION

Our observed NAT yield for all three viruses was 1 in 1528 (0.065%). We estimate NAT could interdict 3272 infectious donations a year among our approximate 5 million annual donations.

Suggestive evidence of association of C-159T functional polymorphism of the CD14 gene with atopic asthma in northern and northwestern Indian populations

CD14 is a lipopolysaccharide receptor known to be an important modulator of Th1-Th2 response during early childhood. Genetic association studies of the CD14 gene with asthma and atopic disorders have shown positive as well as negative results in different ethnic populations. The aim of this study was to test for association of C-159T functional promoter polymorphism with atopic asthma and serum IgE levels in northern and northwestern Indian populations. DNA was assayed for the CD14 C-159T polymorphism in a case-control study involving atopic asthmatics (n=187) and healthy normal controls (n=227), and in a family-based association study of 106 trios. The case-control study showed an association at the genotypic (P=0.0146) as well as the allelic level (P=0.0048). Moreover, we observed a deviation of allelic transmission from random proportions (P=0.024) in the transmission disequilibrium test analysis. When we analyzed our results for serum total IgE levels, against this polymorphism, we observed a difference at the genotypic (P=0.0026) as well as at the allelic level (P=0.0016) in a case-control study, whereas no association in the quantitative transmission disequilibrium test analysis was obtained. These findings provide suggestive evidence of association of the CD14 gene locus with atopic asthma in northern and northwestern Indian populations.