Corrigendum to Contractility defects hinder glycoprotein VI-mediated platelet activation and affect platelet functions beyond clot contraction [Research and Practice in Thrombosis and Haemostasis Volume 8, Issue 1, January 2024, 102322]

[This corrects the article DOI: 10.1016/j.rpth.2024.102322.].

Contractility defects hinder glycoprotein VI-mediated platelet activation and affect platelet functions beyond clot contraction

Background

Active and passive biomechanical properties of platelets contribute substantially to thrombus formation. Actomyosin contractility drives clot contraction required for stabilizing the hemostatic plug. Impaired contractility results in bleeding but is difficult to detect using platelet function tests.

Objectives

To determine how diminished myosin activity affects platelet functions, including and beyond clot contraction.

Methods

Using the myosin IIA-specific pharmacologic inhibitor blebbistatin, we modulated myosin activity in platelets from healthy donors and systematically characterized platelet responses at various levels of inhibition by interrogating distinct platelet functions at each stage of thrombus formation using a range of complementary assays.

Results

Partial myosin IIA inhibition neither affected platelet von Willebrand factor interactions under arterial shear nor platelet spreading and cytoskeletal rearrangements on fibrinogen. However, it impacted stress fiber formation and the nanoarchitecture of cell-matrix adhesions, drastically reducing and limiting traction forces. Higher blebbistatin concentrations impaired platelet adhesion under flow, altered mechanosensing at lamellipodia edges, and eliminated traction forces without affecting platelet spreading, α-granule secretion, or procoagulant platelet formation. Unexpectedly, myosin IIA inhibition reduced calcium influx, dense granule secretion, and platelet aggregation downstream of glycoprotein (GP)VI and limited the redistribution of GPVI on the cell membrane, whereas aggregation induced by adenosine diphosphate or arachidonic acid was unaffected.

Conclusion

Our findings highlight the importance of both active contractile and passive crosslinking roles of myosin IIA in the platelet cytoskeleton. They support the hypothesis that highly contractile platelets are needed for hemostasis and further suggest a supportive role for myosin IIA in GPVI signaling.

Zero-fluoroscopy catheter ablation of supraventricular tachycardias in pediatric population

Funding Acknowledgements

Type of funding sources: None.

Introduction

Catheter ablation (CA) of supraventricular tachycardias (SVTs) in pediatric patients is conventionally performed with the aid of X-ray fluoroscopy. Usage of the three-dimensional (3D) electro-anatomical mapping (EAM) system and the intracardiac echocardiography (ICE) enables zero-fluorscopy ablation, eliminating the harmful effects of the radiation (1-3).

Purpose

We retrospectively analyzed the feasibility, effectiveness and safety of zero-fluoroscopy radiofrequency and cryoablation of various types of SVTs in pediatric patients.

Methods

In this retrospective study, we analyzed consecutive pediatric patients who underwent CA procedure due to SVT in our institution from April 2014 to October 2021. All procedures were performed completely without the use of fluoroscopy. A 3D EAM system and ICE were used as the principal modes of catheter visualisation. Left-sided procedures were done with ICE guided transseptal approach. Radiofrequency was the principal energy source, while cryoablation was used for arrhythmia substrates in the proximity of the conduction system.

Results

The study included 174 consecutive patients (69/174 (66%) female; 12.5 ± 3.9 years; 19.2 ± 3.6 kg/m2). Altogether 176 SVTs were diagnosed and treated. Atrio-ventricular nodal reentry tachycardia (AVNRT) was diagnosed in 45% of cases (80/176), atrio-ventricular reentry tachycardia (AVRT) in 47% (82/176), focal atrial tachycardia (AT) in 7% (13/176), typical atrial flutter (AFL) was treated in only one patient, while 2 patients had multiple arrhythmias (AVNRT and AVRT). In total, 202 procedures were performed. Radiofrequency ablation was performed in 76% (154/202), cryoablation in 20% (40/202) and both in 4% (8/202) of procedures. The acute procedural success rate was 96% (195/202). Procedural success rate was 99% (79/80) for AVNRT, 94% (77/82) for AVRT, 92% (12/13) for AT, and 100% (1/1) for AFL, respectively. There were no major complications in our study group. Follow-up was complete in 99% (172/174) of patients. During the follow-up period of a median of 316 days (181 - 747), 98% of patients were arrhythmia free. On average, 1.16 procedures per patient were performed with the long-term success rate of 99% (79/80), 98% (80/82), 100% (13/13) and 100% (1) for AVNRT, AVRT, AT, and AFL, respectively.

Conclusion

Zero-fluoroscopy CA of various types of SVTs in pediatric population is a feasible, effective, and safe treatment option.

Analysis on the factors related to the acute success rate of fluoroless catheter ablation in patients with supraventricular tachycardias: a single-center experience

Background

In this retrospective study, we aimed to detect factors related to the acute success rate (ASR) of radiofrequency (RFA) and cryo-ablation (CRA) of SVTs guided by three-dimensional (3D) electroanatomical mapping (EAM) system completely without the use of fluoroscopy (FLR).

Methods and results

We analyzed 324 consecutive patients with SVTs [age was 30.65±20.71 (3.6–83.1) years, 147 patients <19 years old and 50.3% (163/224) patients were female]. There were 112 patients with accessory pathways (APs), 36 patients with atrial tachycardia (ATs), and 176 patients with atrioventricular nodal reentrant tachycardia (AVNRT). All procedures [(RFA (n=257), CRA (n=51), combined RFA and CRA (n=16)] were performed guided by the 3D EAM system completely without the use of FLR. Intracardiac echocardiography (ICE) was used as an imaging tool when transseptal approach was needed for treatment of left-sided arrhythmias. The acute success rate (ASR) was 90.4% (293/224). There were no procedural complications. After the first procedure, patients were divided into the “ablation success” group (group I, n=293) and the “ablation failure” group (group II, n=31). Two groups were similar in terms of age, BMI, gender distribution, and type of ablation procedure. In group II, number of ablation lesions was significantly higher than group I [respectively; 17.93±11.7 vs. 10.5±14.5; p=0.003]. Additionally, total ablation time (TAT) [respectively; 552.6±298.6 vs. 449.7±448.1; p=0.1] and total procedural time (TPT) [respectively; 116.3±54.2 vs. 94.5±82.0; p=0.05] were mildly higher. When compared to Group I, the number of patients with right-sided tachycardias was significantly higher in Group II.[67.74% (21/31 vs. 21.5% (63/293; p<0.001]. ASR was the highest for patients with AVNRT and lowest for patients with ATs [respectively; 95.4% (168/176) vs. 75.0% (27/36); p<0.001]. Binary logistic regression analysis (Nagelkerke R Square=0.201) showed that SVTs originating from the right side were an independent risk factor for procedural failure. Patients with right-sided SVTs faced an approximately 11-fold increased risk of failed ablation (OR=10.69, 95% CI 2.49–45.78, p=0.001). Type of arrhythmia, type of ablation procedure, the sex category, age, and BMI were not independent risk factors for failed ablation. A significant risk factor for recurrence could not be detected.

Conclusions

This study revealed that catheter ablation of SVTs completely without the use of fluoroscopy can be performed with high ASR and without procedural complications. Likewise, ASR of fluoroless ablation was the highest for patients with AVNRT and lowest for patients with AT. Moreover, right-sided SVTs were an independent risk factor for ablation failure.

Funding Acknowledgement

Type of funding source: None