Cardiac fibroblasts : Active players in (atrial) electrophysiology?

Body Surface Potential Mapping during Atrial Depolarization in Rats with Post-Infarction Chronic Heart Failure against the Background of Fabomotizole Therapy

Cardiac remodeling in rats with post-infarction chronic heart failure caused by anterior transmural myocardial infarction leads to an atypical location of areas of positive and negative cardioelectric potentials on the body surface before the onset of the PII-wave on the ECG in the limb leads, which is a sign of increased heterogeneity of atrial depolarization associated with the appearance of additional excitation focus in the left atrium. A course of therapy with fabomotizole leads to a decrease in the heterogeneity of atrial depolarization at the initial stages of the formation of the cardioelectric field of the atria on the body surface before the onset of the PII-wave, thereby producing an antiarrhythmic effect.

Implications for neutrophils in cardiac arrhythmias

Cardiac arrhythmias commonly occur as a result of aberrant electrical impulse formation or conduction in the myocardium. Frequently discussed triggers include underlying heart diseases such as myocardial ischemia, electrolyte imbalances, or genetic anomalies of ion channels involved in the tightly regulated cardiac action potential. Recently, the role of innate immune cells in the onset of arrhythmic events has been highlighted in numerous studies, correlating leukocyte expansion in the myocardium to increased arrhythmic burden. Here, we aim to call attention to the role of neutrophils in the pathogenesis of cardiac arrhythmias and their expansion during myocardial ischemia and infectious disease manifestation. In addition, we will elucidate molecular mechanisms associated with neutrophil activation and discuss their involvement as direct mediators of arrhythmogenicity.

Cardiac PDGFRα+ interstitial cells generate spontaneous inward currents that contribute to excitability in the heart

The cell types and conductance that contribute to normal cardiac functions remain under investigation. We used mice that express an enhanced green fluorescent protein (eGFP)-histone 2B fusion protein driven off the cell-specific endogenous promoter for Pdgfra to investigate the distribution and functional role of PDGFRα+ cells in the heart. Cardiac PDGFRα+ cells were widely distributed within the endomysium of atria, ventricle, and sino-atrial node (SAN) tissues. PDGFRα+ cells formed a discrete network of cells, lying in close apposition to neighboring cardiac myocytes in mouse and Cynomolgus monkey (Macaca fascicularis) hearts. Expression of eGFP in nuclei allowed unequivocal identification of these cells following enzymatic dispersion of muscle tissues. FACS purification of PDGFRα+ cells from the SAN and analysis of gene transcripts by qPCR revealed that they were a distinct population of cells that expressed gap junction transcripts, Gja1 and Gjc1. Cardiac PDGFRα+ cells generated spontaneous transient inward currents (STICs) and spontaneous transient depolarizations (STDs) that reversed at 0 mV. Reversal potential was maintained when ECl  = -40 mV. [Na+ ]o replacement and FTY720 abolished STICs, suggesting they were due to a non-selective cation conductance (NSCC) carried by TRPM7. PDGFRα+ cells also express β2 -adrenoceptor gene transcripts, Adrb2. Zinterol, a selective β2 -receptor agonist, increased the amplitude and frequency of STICs, suggesting these cells could contribute to adrenergic regulation of cardiac excitability. PDGFRα+ cells in cardiac muscles generate inward currents via an NSCC. STICs generated by these cells may contribute to the integrated membrane potentials of cardiac muscles, possibly affecting the frequency of pacemaker activity.

Advancing Engineered Heart Muscle Tissue Complexity with Hydrogel Composites

A heart attack results in the permanent loss of heart muscle and can lead to heart disease, which kills more than 7 million people worldwide each year. To date, outside of heart transplantation, current clinical treatments cannot regenerate lost heart muscle or restore full function to the damaged heart. There is a critical need to create engineered heart tissues with structural complexity and functional capacity needed to replace damaged heart muscle. The inextricable link between structure and function suggests that hydrogel composites hold tremendous promise as a biomaterial-guided strategy to advance heart muscle tissue engineering. Such composites provide biophysical cues and functionality as a provisional extracellular matrix that hydrogels cannot on their own. This review describes the latest advances in the characterization of these biomaterial systems and using them for heart muscle tissue engineering. The review integrates results across the field to provide new insights on critical features within hydrogel composites and perspectives on the next steps to harnessing these promising biomaterials to faithfully reproduce the complex structure and function of native heart muscle.

Wnt Signaling in Heart Development and Regeneration

PURPOSE OF REVIEW

Cardiovascular diseases are the leading cause of death worldwide, largely due to the limited regenerative capacity of the adult human heart. In contrast, teleost zebrafish hearts possess natural regeneration capacity by proliferation of pre-existing cardiomyocytes after injury. Hearts of mice can regenerate if injured in a few days after birth, which coincides with the transient capacity for cardiomyocyte proliferation. This review tends to elaborate the roles and mechanisms of Wnt/β-catenin signaling in heart development and regeneration in mammals and non-mammalian vertebrates.

RECENT FINDINGS

Studies in zebrafish, mice, and human embryonic stem cells demonstrate the binary effect for Wnt/β-catenin signaling during heart development. Both Wnts and Wnt antagonists are induced in multiple cell types during cardiac development and injury repair. In this review, we summarize composites of the Wnt signaling pathway and their different action routes, followed by the discussion of their involvements in cardiac specification, proliferation, and patterning. We provide overviews about canonical and non-canonical Wnt activity during heart homeostasis, remodeling, and regeneration. Wnt/β-catenin signaling exhibits biphasic and antagonistic effects on cardiac specification and differentiation depending on the stage of embryogenesis. Inhibition of Wnt signaling is beneficial for cardiac wound healing and functional recovery after injury. Understanding of the roles and mechanisms of Wnt signaling pathway in injured animal hearts will contribute to the development of potential therapeutics for human diseased hearts.

Human Atrial Cardiac Microtissues for Chamber-Specific Arrhythmic Risk Assessment

Introduction

Although atrial fibrillation is the most prevalent disorder of electrical conduction, the mechanisms behind atrial arrhythmias remain elusive. To address this challenge, we developed a robust in vitro model of 3D atrial microtissue from human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes and evaluated chamber-specific chemical responses experimentally and computationally.

Methods

We differentiated atrial and ventricular cardiomyocytes (aCMs/vCMs) from GCaMP6f-expressing hiPSCs and assessed spontaneous AP activity using fluorescence imaging. Self-assembling 3D microtissues were formed with lactate purified CMs and 5% human cardiac fibroblasts and electrically stimulated for one week before high resolution action potential (AP) optical mapping. AP responses to the atrial-specific potassium repolarizing current I _Kur-blocker 4-Aminopyridine (4-AP) and funny current I _f-blocker Ivabradine were characterized within their therapeutic window. Finally, we expanded upon a published hiPSC-CM computational model by incorporating the atrial-specific I _Kur current, modifying ion channel conductances to match the AP waveforms of our microtissues, and employing the updated model to reinforce our experimental findings.

Results

High purity CMs (> 75% cTnT⁺) demonstrated subtype specification by MLC2v expression. Spontaneous beating rates significantly decreased following 3D microtissue formation, with atrial microtissues characterized by their faster spontaneous beating rate, slower AP rise time, and shorter AP duration (APD) compared to ventricular microtissues. We measured atrial-specific responses, including dose-dependent APD prolongation with 4-AP treatment and dose-dependent reduction in spontaneous activity post-Ivabradine treatment.

Conclusion

The presented in vitro platform for screening atrial-specific responses is both robust and sensitive, with high throughput, enabling studies focused at elucidating the mechanisms underlying atrial arrhythmias.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12195-021-00703-x.

Exercising immune cells: The immunomodulatory role of exercise on atrial fibrillation

Exercise training is generally beneficial for cardiovascular health, improving stroke volume, cardiac output, and aerobic capacity. Despite these benefits, some evidence indicates that endurance training may increase the risk of atrial fibrillation (AF), particularly in highly trained individuals. Among multiple mechanisms, autonomic tone changes and atrial remodeling have been proposed as main contributors for exercise-induced AF. However, the contribution of local and systemic immunity is poorly understood in the development of atrial arrhythmogenic substrates. Here we aim to update the field of immunomodulation in the context of exercise and AF by compiling and reconciling the most recent evidence from preclinical and human studies and rationalize the applicability of "lone" AF terminology in athletes.

Heterogeneity and Remodeling of Ion Currents in Cultured Right Atrial Fibroblasts From Patients With Sinus Rhythm or Atrial Fibrillation

Cardiac fibroblasts express multiple voltage-dependent ion channels. Even though fibroblasts do not generate action potentials, they may influence cardiac electrophysiology by electrical coupling via gap junctions with cardiomyocytes, and through fibrosis. Here, we investigate the electrophysiological phenotype of cultured fibroblasts from right atrial appendage tissue of patients with sinus rhythm (SR) or atrial fibrillation (AF). Using the patch-clamp technique in whole-cell mode, we observed steady-state outward currents exhibiting either no rectification or inward and/or outward rectification. The distributions of current patterns between fibroblasts from SR and AF patients were not significantly different. In response to depolarizing voltage pulses, we measured transient outward currents with fast and slow activation kinetics, an outward background current, and an inward current with a potential-dependence resembling that of L-type Ca²⁺ channels. In cell-attached patch-clamp mode, large amplitude, paxilline-sensitive single channel openings were found in ≈65% of SR and ∼38% of AF fibroblasts, suggesting the presence of “big conductance Ca²⁺-activated K⁺ (BK_Ca)” channels. The open probability of BK_Ca was significantly lower in AF than in SR fibroblasts. When cultured in the presence of paxilline, the shape of fibroblasts became wider and less spindle-like. Our data confirm previous findings on cardiac fibroblast electrophysiology and extend them by illustrating differential channel expression in human atrial fibroblasts from SR and AF tissue.

Piezo1 and BKCa channels in human atrial fibroblasts: Interplay and remodelling in atrial fibrillation

AIMS

Atrial Fibrillation (AF) is an arrhythmia of increasing prevalence in the aging populations of developed countries. One of the important indicators of AF is sustained atrial dilatation, highlighting the importance of mechanical overload in the pathophysiology of AF. The mechanisms by which atrial cells, including fibroblasts, sense and react to changing mechanical forces, are not fully elucidated. Here, we characterise stretch-activated ion channels (SAC) in human atrial fibroblasts and changes in SAC- presence and activity associated with AF.

METHODS AND RESULTS

Using primary cultures of human atrial fibroblasts, isolated from patients in sinus rhythm or sustained AF, we combine electrophysiological, molecular and pharmacological tools to identify SAC. Two electrophysiological SAC- signatures were detected, indicative of cation-nonselective and potassium-selective channels. Using siRNA-mediated knockdown, we identified the cation-nonselective SAC as Piezo1. Biophysical properties of the potassium-selective channel, its sensitivity to calcium, paxilline or iberiotoxin (blockers), and NS11021 (activator), indicated presence of calcium-dependent 'big potassium channels' (BK_Ca). In cells from AF patients, Piezo1 activity and mRNA expression levels were higher than in cells from sinus rhythm patients, while BK_Ca activity (but not expression) was downregulated. Both Piezo1-knockdown and removal of extracellular calcium from the patch pipette resulted in a significant reduction of BK_Ca current during stretch. No co-immunoprecipitation of Piezo1 and BK_Ca was detected.

CONCLUSIONS

Human atrial fibroblasts contain at least two types of ion channels that are activated during stretch: Piezo1 and BK_Ca. While Piezo1 is directly stretch-activated, the increase in BK_Ca activity during mechanical stimulation appears to be mainly secondary to calcium influx via SAC such as Piezo1. During sustained AF, Piezo1 is increased, while BK_Ca activity is reduced, highlighting differential regulation of both channels. Our data support the presence and interplay of Piezo1 and BK_Ca in human atrial fibroblasts in the absence of physical links between the two channel proteins.

Higher Incidence of Atrial Fibrillation in Left Ventricular-to-Right Atrial Shunt Patients

Background: The possible association between atrial fibrillation (AF) and left ventricular-to-right atrial shunt (LVRAS) has never been reported yet. The present study investigated the incidence of AF in LVRAS. Methods: This was a retrospective study of consecutive patients undergoing echocardiography at a single tertiary center. Clinical data, laboratory results and echocardiography parameters such as right atrial area (RAA), right ventricular end diastolic diameter (RVDD) and left atrial diameter (LAD) were compared between LVRAS group and non-LVRAS patients, and between AF and non-AF patients. Propensity score matching was performed to decrease the effect of confounders. Logistic regression analysis and mediation analysis were used to estimate the relationship between LVRAS and AF. Results: A total of 3,436 patients were included, and the incidence of LVRAS was 1.16% (n = 40). The LVRAS group had significantly larger RAA, RVDD and LAD compared with non-LVRAS group. Those who suffered from AF showed larger RAA, RVDD and LAD compared with those who maintained sinus rhythm. Multivariable logistic regression showed that gender (OR: 0.608), age (OR: 1.048), LAD (OR: 1.111), mean pulmonary artery blood pressure (mPAP, OR: 1.023), TR (OR: 2.309) and LVRAS (OR: 12.217) were significant factors for AF. RAA could partially mediate the relationship between LVRAS and AF according to the result of mediation analysis. Conclusions: Our study suggested that LVRAS, TR, LAD, mPAP, age and male were risk factors for AF. RA enlargement might underlie mechanism in the higher incidence of AF in LVRAS patients. These findings should be confirmed in larger prospective studies.

Role of TRPM7 in cardiac fibrosis: A potential therapeutic target (Review)

Cardiac fibrosis is a hallmark of cardiac remodeling associated with nearly all forms of heart disease. Clinically, no effective therapeutic drugs aim to inhibit cardiac fibrosis, owing to the complex etiological heterogeneity and pathogenesis of this disease. A two-in-one protein structure, a ubiquitous expression profile and unique biophysical characteristics enable the involvement of transient receptor potential melastatin-subfamily member 7 (TRPM7) in the pathogenesis and development of fibrosis-related cardiac diseases, such as heart failure (HF), cardiomyopathies, arrhythmia and hyperaldosteronism. In response to a variety of stimuli, multiple bioactive molecules can activate TRPM7 and related signaling pathways, leading to fibroblast proliferation, differentiation and extracellular matrix production in cardiac fibroblasts. TRPM7-mediated Ca²⁺ signaling and TGF-β1 signaling pathways are critical for the formation of fibrosis. Accumulating evidence has demonstrated that TRPM7 is a potential pharmacological target for halting the development of fibrotic cardiac diseases. Reliable drug-like molecules for further development of high-affinity in vivo drugs targeting TRPM7 are urgently needed. The present review discusses the widespread and significant role of TRPM7 in cardiac fibrosis and focuses on its potential as a therapeutic target for alleviating heart fibrogenesis.

TRPM4 non-selective cation channel in human atrial fibroblast growth

Cardiac fibroblasts play an important role in cardiac matrix turnover and are involved in cardiac fibrosis development. Ca²⁺ is a driving belt in this phenomenon. This study evaluates the functional expression and contribution of the Ca²⁺-activated channel TRPM4 in atrial fibroblast phenotype. Molecular and electrophysiological investigations were conducted in human atrial fibroblasts in primary culture and in atrial fibroblasts obtained from wild-type and transgenic mice with disrupted Trpm4 gene (Trpm4^-/-). A typical TRPM4 current was recorded on human cells (equal selectivity for Na⁺ and K⁺, activation by internal Ca²⁺, voltage sensitivity, conductance of 23.2 pS, inhibition by 9-phenanthrol (IC₅₀ = 6.1 × 10^-6 mol L^-1)). Its detection rate was 13% on patches at days 2-4 in culture but raised to 100% on patches at day 28. By the same time, a cell growth was observed. This growth was smaller when cells were maintained in the presence of 9-phenanthrol. Similar cell growth was measured on wild-type mice atrial fibroblasts during culture. However, this growth was minimized on Trpm4^-/- mice fibroblasts compared to control animals. In addition, the expression of alpha smooth muscle actin increased during culture of atrial fibroblasts from wild-type mice. This was not observed in Trpm4^-/- mice fibroblasts. It is concluded that TRPM4 participates in fibroblast growth and could thus be involved in cardiac fibrosis.

From Human Pluripotent Stem Cells to 3D Cardiac Microtissues: Progress, Applications and Challenges

The knowledge acquired throughout the years concerning the in vivo regulation of cardiac development has promoted the establishment of directed differentiation protocols to obtain cardiomyocytes (CMs) and other cardiac cells from human pluripotent stem cells (hPSCs), which play a crucial role in the function and homeostasis of the heart. Among other developments in the field, the transition from homogeneous cultures of CMs to more complex multicellular cardiac microtissues (MTs) has increased the potential of these models for studying cardiac disorders in vitro and for clinically relevant applications such as drug screening and cardiotoxicity tests. This review addresses the state of the art of the generation of different cardiac cells from hPSCs and the impact of transitioning CM differentiation from 2D culture to a 3D environment. Additionally, current methods that may be employed to generate 3D cardiac MTs are reviewed and, finally, the adoption of these models for in vitro applications and their adaptation to medium- to high-throughput screening settings are also highlighted.

Human-iPSC-Derived Cardiac Stromal Cells Enhance Maturation in 3D Cardiac Microtissues and Reveal Non-cardiomyocyte Contributions to Heart Disease

Cardiomyocytes (CMs) from human induced pluripotent stem cells (hiPSCs) are functionally immature, but this is improved by incorporation into engineered tissues or forced contraction. Here, we showed that tri-cellular combinations of hiPSC-derived CMs, cardiac fibroblasts (CFs), and cardiac endothelial cells also enhance maturation in easily constructed, scaffold-free, three-dimensional microtissues (MTs). hiPSC-CMs in MTs with CFs showed improved sarcomeric structures with T-tubules, enhanced contractility, and mitochondrial respiration and were electrophysiologically more mature than MTs without CFs. Interactions mediating maturation included coupling between hiPSC-CMs and CFs through connexin 43 (CX43) gap junctions and increased intracellular cyclic AMP (cAMP). Scaled production of thousands of hiPSC-MTs was highly reproducible across lines and differentiated cell batches. MTs containing healthy-control hiPSC-CMs but hiPSC-CFs from patients with arrhythmogenic cardiomyopathy strikingly recapitulated features of the disease. Our MT model is thus a simple and versatile platform for modeling multicellular cardiac diseases that will facilitate industry and academic engagement in high-throughput molecular screening.

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Cardiac fibroblasts and endothelial cells induce hiPSC-cardiomyocyte maturation

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CX43 gap junctions form between cardiac fibroblasts and cardiomyocytes

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cAMP-pathway activation contributes to hiPSC-cardiomyocyte maturation

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Patient-derived hiPSC-cardiac fibroblasts cause arrhythmia in microtissues

Macrophages: First guards in the prevention of cardiovascular diseases

Cardiovascular diseases (CVD) remain one of the leading causes of mortality worldwide, especially in developing countries. It is widely known that severe inflammation can lead to atherosclerosis, which can cause various downstream pathologies, including myocardial injury and viral myocarditis. To date, several strategies have been proposed to prevent and cure CVD. The use of targeting macrophages has emerged as one of the most effective therapeutic approaches. Macrophages play a crucial role in eliminating senescent and dead cells while maintaining myocardial electrical activity and repairing myocardial injury. They also contribute to tissue repair and remodeling and plaque stabilization. Targeting macrophage pathways can, therefore, be advantageous in CVD care since it can lead to decreased aggregation of mononuclear cells at the injured site in the heart. Furthermore, it inhibits the development of pro-inflammatory factors, facilitates cholesterol outflow, and reduces the lipid concentration. More in-depth studies are still needed to formulate a comprehensive classification of phenotypes for different macrophages and determine their roles in the pathogenesis of CVD. In this review, we summarize the recent advances in the understanding of the role of macrophages in the prevention and cure of CVD.

Arnebiae Radix prevents atrial fibrillation in rats by ameliorating atrial remodeling and cardiac function

ETHNOPHARMACOLOGICAL RELEVANCE

Arnebiae Radix, a common herbal medicine in China, is often utilized to treat blood-heat syndrome and has been reported to exert an effect on the heart.

AIM OF THE STUDY

The combination of acetylcholine (Ach) and CaCl₂ has been widely used to induce atrial fibrillation (AF) in animals. However, whether Arnebiae Radix displays any preventive action on Ach-CaCl₂ induced AF in rats remains uncertain. In our study, we attempted to investigate the protective effects of Arnebiae Radix on Ach-CaCl₂ induced AF compared to amiodarone, which was employed as the positive control.

MATERIALS AND METHODS

To establish the AF model, SD rats were treated with a mixture of 0.1 mL/100 g Ach-CaCl₂ (60 μg/mL Ach and 10 mg/mL CaCl₂) by tail vein injection for 7 days. Rats were also given a gavage of Arnebiae Radix (0.18 g/mL) one week before or concurrently with the establishment of the AF model. At the end of the experimental period, the induction, duration and timing of AF were monitored using electrocardiogram recordings. Left atrial tissues were stained to observe the level of fibrosis. Electrophysiological measurements were used to examine atrial size and function.

RESULTS

In Ach-CaCl₂-induced AF rats, Arnebiae Radix decreased AF induction, duration and susceptibility to AF. In addition, Arnebiae Radix significantly reduced atrial fibrosis and inhibited atrial enlargement induced by Ach-CaCl₂. Moreover, there was an apparent improvement in cardiac function in the Arnebiae Radix-treated group.

CONCLUSIONS

Our findings indicate that Arnebiae Radix treatment can attenuate Ach-CaCl₂-induced atrial injury and serve as an effective therapeutic strategy for the treatment of AF in the future.

Living myofibroblast-silicon composites for probing electrical coupling in cardiac systems

Traditional bioelectronics, primarily comprised of nonliving synthetic materials, lack cellular behaviors such as adaptability and motility. This shortcoming results in mechanically invasive devices and nonnatural signal transduction across cells and tissues. Moreover, resolving heterocellular electrical communication in vivo is extremely limited due to the invasiveness of traditional interconnected electrical probes. In this paper, we present a cell-silicon hybrid that integrates native cellular behavior (e.g., gap junction formation and biosignal processing) with nongenetically enabled photosensitivity. This hybrid configuration allows interconnect-free cellular modulation with subcellular spatial resolution for bioelectric studies. Specifically, we hybridize cardiac myofibroblasts with silicon nanowires and use these engineered hybrids to synchronize the electrical activity of cardiomyocytes, studying heterocellular bioelectric coupling in vitro. Thereafter, we inject the engineered myofibroblasts into heart tissues and show their ability to seamlessly integrate into contractile tissues in vivo. Finally, we apply local photostimulation with high cell specificity to tackle a long-standing debate regarding the existence of myofibroblast-cardiomyocyte electrical coupling in vivo.

Atria-selective antiarrhythmic drugs in need of alliance partners

Atria-selective antiarrhythmic drugs in need of alliance partners. Guideline-based treatment of atrial fibrillation (AF) comprises prevention of thromboembolism and stroke, as well as antiarrhythmic therapy by drugs, electrical rhythm conversion, ablation and surgical procedures. Conventional antiarrhythmic drugs are burdened with unwanted side effects including a propensity of triggering life-threatening ventricular fibrillation. In order to solve this therapeutic dilemma, 'atria-selective' antiarrhythmic drugs have been developed for the treatment of supraventricular arrhythmias. These drugs are designed to aim at atrial targets, taking advantage of differences in atrial and ventricular ion channel expression and function. However it is not clear, whether such drugs are sufficiently antiarrhythmic or whether they are in need of an alliance partner for clinical efficacy. Atria-selective Na⁺ channel blockers display fast dissociation kinetics and high binding affinity to inactivated channels. Compounds targeting atria-selective K⁺ channels include blockers of ultra rapid delayed rectifier (Kv1.5) or acetylcholine-activated inward rectifier K⁺ channels (Kir3.x), inward rectifying K⁺ channels (Kir2.x), Ca²⁺-activated K⁺ channels of small conductance (SK), weakly rectifying two-pore domain K⁺ channels (K_2P), and transient receptor potential channels (TRP). Despite good antiarrhythmic data from in-vitro and animal model experiments, clinical efficacy of atria-selective antiarrhythmic drugs remains to be demonstrated. In the present review we will briefly summarize the novel compounds and their proposed antiarrhythmic action. In addition, we will discuss the evidence for putative improvement of antiarrhythmic efficacy and potency by addressing multiple pathophysiologically relevant targets as possible alliance partners.

Interatrial block in prediction of all-cause mortality after first-ever ischemic stroke

Background

Interatrial block (IAB) is an ECG indicator of atrial fibrosis related to atrial remodeling and thrombus formation thus leading to embolic stroke and increasing mortality. We aimed to assess weather IAB predicted all-cause mortality during 10 years after ischemic stroke.

Methods

The study sample comprised 235 patients (median age 74 (interquartile range 25–75% 65–81) years, 95 female) included in the Lund Stroke Register in 2001–2002, who had sinus rhythm ECGs at stroke admission. IAB was defined as a P-wave duration ≥120 ms without = partial IAB (n = 56) or with = advanced IAB (n = 41) biphasic morphology (±) in the inferior ECG leads. All-cause mortality was assessed via linkage with the Swedish Causes of Death Register.

Results

During follow-up 126 patients died (54%). Advanced IAB, but not partial, was associated with all-cause mortality in univariate Cox regression analysis (hazard ratio (HR) 1.98, 95% CI 1.27–3.09, p = 0.003). After adjustment for age, gender, severity of stroke measured by NIHSS scale and smoking status in patients without additional comorbidities advanced IAB independently predicted all-cause mortality (HR 7.89, 95% CI 2.01–30.98, p = 0.003), while in patients with comorbidities it did not (HR 1.01 95% CI 0.59–1.72, p = 0.966).

Conclusion

Advanced IAB predicted all-cause mortality after ischemic stroke, but mostly in patients without additional cardiovascular comorbidities.

Decreased platelet-to-lymphocyte ratio as predictor of thrombogenesis in nonvalvular atrial fibrillation

BACKGROUND

Inflammation plays a key role in the progression of atrial fibrillation and its related prothrombotic state. The platelet-to-lymphocyte ratio (PLR) is an easily obtainable biomarker of inflammatory burden. Decreased left atrial appendage flow velocity (LAA-FV) reflects blood stasis, and left atrial strain is a manifestation of atrial remodeling. This study examined the role of PLR in reflecting decreased LAA-FV and its correlation with impaired left atrial strain.

METHODS

In 54 patients with nonvalvular atrial fibrillation, LAA-FV and left atrial strain were measured by echocardiography. The PLR was calculated from a complete blood count.

RESULTS

The PLR was lower in the group of patients with decreased LAA-FV (84.22 [IQR, 69.87-98.17 cm/s] vs. 103.27 [IQR, 90.37-127.16 cm/s]; p = 0.018). PLR was predictive of decreased LAA-FV with a sensitivity of 66.7% and a specificity of 83.3%. In a receiver operator characteristic curve analysis, using a cut-off value of 88.16, the area under the curve for PLR as a predictor of decreased LAA-FV was 0.726 (p = 0.018). Furthermore, the patients with a PLR of < 88.16 had a lower left atrial strain than those with a PLR of > 88.16 (0.38 vs. 0.77, p = 0.02).

CONCLUSION

The PLR was lower in patients with nonvalvular atrial fibrillation and with a decreased LAA-FV. Its correlation with left atrial strain might indicate the role of inflammation in the progression of atrial remodeling and in the prothrombotic state.