Impact of artificial intelligence arrhythmia mapping on time to first ablation, procedure duration, and fluoroscopy use.

INTRODUCTION: Artificial intelligence (AI) ECG arrhythmia mapping provides arrhythmia source localization using 12-lead ECG data; whether this information impacts procedural efficiency is unknown. We performed a retrospective, case-control study to evaluate the hypothesis that AI ECG mapping may reduce time to ablation, procedural duration, and fluoroscopy. MATERIALS AND METHODS: Cases in which system output was used were retrospectively enrolled according to IRB-approved protocols at each site. Matched control cases were enrolled in reverse chronological order beginning on the last day for which the technology was unavailable. Controls were matched based upon physician, institution, arrhythmia, and a predetermined complexity rating. Procedural metrics, fluoroscopy data, and clinical outcomes were assessed from time-stamped medical records. RESULTS: The study group consisted of 28 patients (age 65 ± 11 years, 46% female, left atrial dimension 4.1 ± 0.9 cm, LVEF 50 ± 18%) and was similar to 28 controls. The most common arrhythmia types were atrial fibrillation (n = 10), premature ventricular complexes (n = 8), and ventricular tachycardia (n = 6). Use of the system was associated with a 19.0% reduction in time to ablation (133 ± 48 vs. 165 ± 49 min, p = 0.02), a 22.6% reduction in procedure duration (233 ± 51 vs. 301 ± 83 min, p < 0.001), and a 43.7% reduction in fluoroscopy (18.7 ± 13.3 vs. 33.2 ± 18.0 min, p < 0.001) versus controls. At 6 months follow-up, arrhythmia-free survival was 73.5% in the study group and 63.3% in the control group (p = 0.56). CONCLUSION: Use of forward-solution AI ECG mapping is associated with reductions in time to first ablation, procedure duration, and fluoroscopy without an adverse impact on procedure outcomes or complications.

NOD-like receptor protein 3 activation causes spontaneous inflammation and fibrosis that mimics human NASH.

BACKGROUND AND AIMS: The NOD-like receptor protein 3 (NLRP3) inflammasome is a central contributor to human acute and chronic liver disease, yet the molecular and cellular mechanisms by which its activation precipitates injury remain incompletely understood. Here, we present single cell transcriptomic profiling of livers from a global transgenic tamoxifen-inducible constitutively activated Nlrp3A350V mutant mouse, and we investigate the changes in parenchymal and nonparenchymal liver cell gene expression that accompany inflammation and fibrosis. APPROACH AND RESULTS: Our results demonstrate that NLRP3 activation causes chronic extramedullary myelopoiesis marked by myeloid progenitors that differentiate into proinflammatory neutrophils, monocytes, and monocyte-derived macrophages. We observed prominent neutrophil infiltrates with increased Ly6gHI and Ly6gINT cells exhibiting transcriptomic signatures of granulopoiesis typically found in the bone marrow. This was accompanied by a marked increase in Ly6cHI monocytes differentiating into monocyte-derived macrophages that express transcriptional programs similar to macrophages of NASH models. NLRP3 activation also down-regulated metabolic pathways in hepatocytes and shifted hepatic stellate cells toward an activated profibrotic state based on expression of collagen and extracellular matrix regulatory genes. CONCLUSIONS: These results define the single cell transcriptomes underlying hepatic inflammation and fibrosis precipitated by NLRP3 activation. Clinically, our data support the notion that NLRP3-induced mechanisms should be explored as therapeutic target in NASH-like inflammation.

SiglecF(HI) Marks Late-Stage Neutrophils of the Infarcted Heart: A Single-Cell Transcriptomic Analysis of Neutrophil Diversification.

Background Neutrophils are thought to be short-lived first responders to tissue injuries such as myocardial infarction (MI), but little is known about their diversification or dynamics. Methods and Results We permanently ligated the left anterior descending coronary arteries of mice and performed single-cell RNA sequencing and analysis of >28 000 neutrophil transcriptomes isolated from the heart, peripheral blood, and bone marrow of mice on days 1 to 4 after MI or at steady-state. Unsupervised clustering of cardiac neutrophils revealed 5 major subsets, 3 of which originated in the bone marrow, including a late-emerging granulocyte expressing SiglecF, a marker classically used to define eosinophils. SiglecFHI neutrophils represented ≈25% of neutrophils on day 1 and grew to account for >50% of neutrophils by day 4 post-MI. Validation studies using quantitative polymerase chain reaction of fluorescent-activated cell sorter sorted Ly6G+SiglecFHI and Ly6G+SiglecFLO neutrophils confirmed the distinct nature of these populations. To confirm that the cells were neutrophils rather than eosinophils, we infarcted GATA-deficient mice (∆dblGATA) and observed similar quantities of infiltrating Ly6G+SiglecFHI cells despite marked reductions of conventional eosinophils. In contrast to other neutrophil subsets, Ly6G+SiglecFHI neutrophils expressed high levels of Myc-regulated genes, which are associated with longevity and are consistent with the persistence of this population on day 4 after MI. Conclusions Overall, our data provide a spatial and temporal atlas of neutrophil specialization in response to MI and reveal a dynamic proinflammatory cardiac Ly6G+SigF+(Myc+NFÏ°B+) neutrophil that has been overlooked because of negative selection.

The myeloid type I interferon response to myocardial infarction begins in bone marrow and is regulated by Nrf2-activated macrophages.

Sterile tissue injury is thought to locally activate innate immune responses via damage-associated molecular patterns (DAMPs). Whether innate immune pathways are remotely activated remains relatively unexplored. Here, by analyzing ~145,000 single-cell transcriptomes at steady state and after myocardial infarction (MI) in mice and humans, we show that the type I interferon (IFN) response, characterized by expression of IFN-stimulated genes (ISGs), begins far from the site of injury, in neutrophil and monocyte progenitors within the bone marrow. In the peripheral blood of patients, we observed defined subsets of ISG-expressing neutrophils and monocytes. In the bone marrow and blood of mice, ISG expression was detected in neutrophils and monocytes and their progenitors, intensified with maturation at steady-state and after MI, and was controlled by Tet2 and Irf3 transcriptional regulators. Within the infarcted heart, ISG-expressing cells were negatively regulated by Nrf2 activation in Ccr2- steady-state cardiac macrophages. Our results show that IFN signaling begins in the bone marrow, implicate multiple transcriptional regulators (Tet2, Irf3, and Nrf2) in governing ISG expression, and provide a clinical biomarker (ISG score) for studying IFN signaling in patients.

Characteristics and Outcomes of Methamphetamine Abuse Among Veterans With Heart Failure.

Methamphetamine is one of the most commonly abused illicit substances worldwide. Chronic methamphetamine abuse (MA) is associated with the development of a dilated cardiomyopathy. MA in patients with heart failure (MethHF) is increasingly reported yet poorly characterized. This was a retrospective cohort study of veterans treated at the VA Medical Center in San Diego between 2005 and 2015 with a diagnosis of HF and a history of MA. The incidence of MA each year was calculated, and clinical characteristics and outcomes of veterans with HF with and without MA were compared. Among 9,491 veterans with HF, 429 were identified as having a history of MA. Between 2006 and 2015, the incidence of MA in veterans with HF doubled from 3.44% to 6.70%. Of the 429 identified, 106 veterans had a hospitalization for HF and they were compared with veterans with HF without evidence of MA (HF). Compared with veterans with HF, veterans with MethHF were significantly younger (60.7 ± 7.3 vs 71.6 ± 11.6 years, p <0.001), with more frequent co-morbid post-traumatic stress disorder (16.8% vs 4.4%, p = 0.006), depression (28.7% vs 11.0%, p = 0.002), homelessness (27.9% vs 8.9%, p = 0.001), and unemployment (55.8% vs 30.0%, p <0.001). Despite their younger age, veterans with MethHF had high rates of HF readmission or emergency room visit (49% vs 38% in MethHF vs HF, p = 0.34) and mortality at 6 months (27% vs 38% in MethHF vs HF, p = 0.10) compared with HF. In conclusion, MA in veterans with HF is on the rise. Certain demographic and clinical characteristics of veterans with MethHF may contribute to their poor outcomes.

ST2 elevation in heart failure, predictive of a high early mortality.

BACKGROUND: Soluble suppression of tumorigenicity-2 (sST2) is a novel biomarker shown to be useful for prognostic assessment in heart failure (HF). However, very limited data exists about its prognostic utility in patients with HF in India. METHODS: We studied 150 patients [mean age 67.7 ± 13.3, 93 (62%) males], hospitalized with clinical HF, irrespective of their left ventricular ejection fraction (LVEF). HF was confirmed by N-terminal probrain natriuretic peptide (NT-proBNP) value above 125 ng/L. Primary end point was death or cardiac transplant at 1-year follow-up, with additional telephonic follow-up performed at 2 years. The clinical outcomes were correlated with the sST2 values obtained at the time of initial hospitalization. RESULTS: HF was ischemic in origin in 82.0% patients. The primary outcome occurred in 9.3% patients at the end of 1-year follow-up and in 16.7% patients at the end of 2 years. The patients who had events had significantly higher NT-proBNP and sST2 values, but there was no difference in the clinical characteristics, cause of HF, baseline LVEF, or serum creatinine. The patients with elevated sST2 levels (>35 ng/mL) had substantially higher event rates than those with normal sST2 levels (13.7% vs 0.0% at 1-year, P = 0.005; 22.5% vs 4.2% at 2-years, P = 0.004). On multivariate analysis, sST2 was the strongest predictor of adverse outcomes at both 1-year and 2-year follow-ups. CONCLUSION: In patients hospitalized for HF, elevated sST2 >35 ng/mL at the time of initial hospitalization was associated with significantly high mortality over a 2-year period. The prognostic value of sST2 was incremental to that of NT-proBNP. These findings suggest that a single elevated sST2 value at the time of hospitalization should alert the physicians about the high risk of adverse outcomes and should help facilitate timely intensification of HF treatment.

Clinical Applications of Biomarkers in Atrial Fibrillation.

While biomarkers have greatly impacted the diagnosis and management of myocardial infarction and heart failure, the use of biomarkers has been slow to permeate management of atrial fibrillation. Guideline recommendations on the use of biomarkers in atrial fibrillation were virtually nonexistent until the 2016 European Society of Cardiology guidelines on atrial fibrillation offered a class IIb recommendation to consider using biomarkers such as high-sensitivity troponin and natriuretic peptide to further refine stroke and bleeding risk in atrial fibrillation patients. Biomarker levels have been associated with incident atrial fibrillation, postoperative atrial fibrillation, acute atrial fibrillation, diagnosis of myocardial infarction and heart failure in atrial fibrillation, and prognosis in atrial fibrillation. This review will offer an in-depth survey of current evidence on the use of biomarkers in atrial fibrillation and propose clinical algorithms to aid the internist in using biomarkers in atrial fibrillation management.