Publications by authors named "Taro Koya"
Background: Anemia is frequently observed and associated with mortality in patients with heart failure (HF). Although the quality of erythropoiesis is an intrinsic aspect of anemia's pathophysiology, its prognostic value in HF patients is unclear.
Methods: Between January 2020 and October 2023, 1,328 symptomatic patients with chronic HF from a multicenter registry were prospectively examined.
Effects of In Vivo Contact Force on Pulsed-Field Ablation Efficacy in Porcine Ventricles.
J Cardiovasc Electrophysiol
March 2025
Background: Pulsed-field ablation (PFA) is an innovative non-thermal method for arrhythmia treatment. The efficacy of various PFA configurations in relation to contact force (CF) has not been well-studied in vivo.
Objectives: This study evaluated the effect of CF on acute bipolar PFA lesions in both a vegetal and an in vivo porcine heart model.
Background: Power-controlled radiofrequency ablation with irrigated-tip catheters has been the norm for ventricular ablation for almost 2 decades. New catheter technology has recently integrated more accurate tissue temperature sensing enabling temperature-controlled irrigated ablation. We aimed to investigate the in vivo ablation parameters and lesion formation characteristics in ventricular myocardium using a novel temperature-controlled radiofrequency catheter.
View Article and Find Full Text PDFLocal calcium chloride infusion after pulsed field ablation enhances acute efficacy of cardiac electroporation.
J Cardiovasc Electrophysiol
December 2024
Introduction: Pulsed field ablation (PFA) has emerged as an innovative therapy for cardiac arrhythmias. Drawing parallels with PFA's application in solid tumors, calcium chloride (CaCl) as an adjuvant therapy, known as calcium electroporation, may amplify PFA's apoptotic effects. We propose that PFA in the atrium could enhance calcium uptake through PFA-created pores, thereby increasing ablation efficacy even at reduced power levels by exploiting PFA's permeabilization effects.
View Article and Find Full Text PDFNormalization of increasing shocking coil impedance with full output synchronized shock.
J Cardiovasc Electrophysiol
November 2024
Article Synopsis
- - Impedance is an important factor for cardiovascular implantable electronic devices (CIEDs), and low voltage sub-threshold measurement (LVSM) is commonly used to measure it, although it can sometimes be inaccurate due to tissue changes.
- - A case study showed that elevated LVSM shock impedance (LVSM-SI) occurred 8 years after lead implantation, likely due to tissue encapsulation around the lead, but normal values were found after administering a high voltage shock.
- - The study suggests that performing a full-output synchronized shock test can help evaluate high voltage shock impedance (HVSI) when LVSM-SI readings are abnormal, potentially restoring normal LVSM-SI values.
Article Synopsis
- - This study examined how self-care behaviors affect mortality in chronic heart failure (CHF) patients, focusing on those with and without recent hospitalizations for heart failure.
- - Researchers analyzed data from 1,907 CHF patients in Japan, finding that those with poor self-care (scores < 70 on a self-care scale) were more likely to face death or rehospitalization if they had been recently hospitalized for heart failure.
- - The results suggest that self-care education is crucial for patients who have recently been hospitalized, as it significantly impacts their health outcomes.
Article Synopsis
- Epicardial adipose tissue (EAT) influences atrial fibrillation (AF) but its role in postoperative AF (POAF) is not well understood; this study examines how EAT relates to POAF in cardiovascular surgery patients.
- Out of 53 patients, 34% experienced POAF within a week after surgery, but no major differences in EAT profiles were found between patients with and without POAF.
- Key findings include that higher levels of tumor necrosis factor-alpha (TNF-α) mRNA are linked to increased POAF risk, while larger adipocyte sizes correlate inversely with POAF onset; mitochondrial OXPHOS was unrelated to POAF but associated with secretory activities and adipocyte
Article Synopsis
- Scientists are studying a new way to treat a heart problem called atrial fibrillation (AF) using special light instead of painful electric shocks.
- This method uses light to change how cells in the heart behave, which could potentially stop the heart from beating too fast.
- The study found that shining light on the heart cells helped them stay in a normal rhythm, showing that this technique might be a promising and painless treatment for heart issues in the future.
Article Synopsis
- Recent studies indicate that SGLT2 inhibitors like empagliflozin may lower the risk of atrial fibrillation in diabetes patients by reducing oxidative stress linked to mitochondrial-ROS generation.
- In a rat model of type-2 diabetes, treating with empagliflozin improved heart function by reducing atrial tachyarrhythmia, fibrosis, and mitochondrial dysfunction that are exacerbated in diabetes.
- The findings highlight empagliflozin's potential to enhance mitochondrial health and cardiac function, suggesting it could serve as a beneficial treatment for diabetes-related heart issues.
Fragmented QRS (fQRS) on a 12-lead electrocardiogram is a known marker of fatal arrhythmias or cardiac adverse events in ischemic and non-ischemic cardiomyopathy patients. Nonetheless, the association between fQRS and clinical outcomes in patients with cardiac sarcoidosis (CS) remains unclear. Herein, we investigated whether fQRS is associated with long-term clinical outcomes in CS patients.
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- Diabetic cardiomyopathy increases the risk of fatal ventricular arrhythmias, and the effects of the SGLT2 inhibitor empagliflozin (EMPA) on heart protection have not been extensively studied.
- In experiments using diabetic and control mice, EMPA treatment preserved heart function, reduced premature ventricular complexes during arrhythmia induction, and normalized calcium handling in diabetic cardiomyocytes.
- The improvements seen with EMPA were linked to decreased glucose uptake and reduced autophosphorylation of specific proteins, suggesting that managing glucose levels may help mitigate arrhythmia risks in diabetic heart conditions.
Article Synopsis
- The study investigates the applicability of new iron deficiency (ID) criteria in Japanese patients with heart failure (HF), shifting focus from previously established guidelines.
- Out of 763 chronic HF patients, 28% met the new criteria while 58% met the guideline criteria, with the study finding no significant difference in all-cause mortality between those who met the guideline ID criteria and those who didn't.
- However, the proposed criteria were linked to higher mortality risk, indicating that they may be more applicable and beneficial for assessing ID in the Japanese HF population.
Pharmacological nNOS inhibition modified small-conductance Ca-activated K channel without altering Ca dynamics.
Am J Physiol Heart Circ Physiol
November 2022
Article Synopsis
- Atrial fibrillation (AF) leads to electrical changes in the heart, with the small-conductance Ca-activated K (SK) channel playing a crucial role, though its activation mechanism is still not well understood.
- In a study using rat hearts, researchers inhibited neuronal nitric oxide synthase (nNOS) to explore its effects on atrial tachyarrhythmia (ATA) and used specific blockers to investigate the SK channel's influence on action potential duration (APD) and other parameters.
- The findings revealed that inhibiting nNOS increased ATA inducibility and shortened APD, while the SK channel blocker apamin counteracted these effects without changing calcium transients, suggesting that posttranslational modifications of SK channels may
Article Synopsis
- - An increase in diastolic calcium levels in heart cells is linked to heart failure and can lead to dangerous heart rhythms; the study explores if mitochondria can help manage this calcium increase.
- - Researchers used a mouse model of heart failure and tested the effects of kaempferol on calcium dynamics and heart function, observing improved outcomes in calcium regulation and reduced arrhythmias.
- - Findings suggest that mitochondria can partially compensate for high calcium levels in heart failure, offering new avenues for treatments addressing heart failure-related arrhythmias.
Background: Electrical storms (ESs) in patients with structural heart disease (SHD) have been reported to be associated with a poor prognosis. However, the detailed cause of death and influence of implantable cardioverter defibrillator (ICD) therapy in ES patients have not been fully investigated. Therefore, we sought to explore the detailed clinical course after an ES and the impact of the ICD therapy in patients with SHDs.
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- Doctors can do a special heart surgery called epicardial catheter ablation for patients who have had heart surgery before.
- They used a method called thoracotomy to reach a specific part of the heart to fix a problem called ventricular tachycardia (VT) in a patient with a certain heart condition.
- By using 3D images and previous tests, they could safely do this surgery with less invasion and successfully stop the VT.
Recurrence of atrial tachyarrhythmias (ATA) following catheter ablation for atrial fibrillation (AF) is often associated with the recovery of conduction into previously isolated pulmonary veins (PVs). Little evidence concerning repeat PV isolation (PVI) and non-PV ATA ablation has been reported. This study aimed to explore the clinical outcome of recurrent ATA ablation after PVI and the difference between patients with and without non-PV ATA.
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- Hypertrophic cardiomyopathy (HCM) with an apical aneurysm (AA) is uncommon but can trigger severe ventricular tachycardias (VTs), often linked to a specific area in the heart called the central isthmus.
- The report discusses a unique case where a patient with HCM and AA successfully underwent an epicardial ablation procedure to treat refractory VT stemming from the true apex of the aneurysm.
- During the ablation, mid-diastolic electrical signals were detected in the surrounding scar tissue, and applying radiofrequency energy effectively stopped the VT from occurring again.
Article Synopsis
- - Epirubicin-based chemotherapy, though infrequently, can lead to heart failure, while bevacizumab is now commonly used for recurrent breast cancer treatment despite its rare risk of heart-related issues.
- - A case study highlights a breast cancer patient who experienced reversible cardiac dysfunction linked to both bevacizumab and epirubicin, resulting in blood clots in the heart's left atrium and ventricle.
- - This situation emphasizes the need for personalized medical planning for patients undergoing anti-cancer treatments to manage potential cardiovascular complications effectively.
Background: Atrial fibrillation (AF) is an important prognostic determinant in heart failure (HF) with preserved ejection fraction (HFpEF). However, it is unclear which HFpEF phenotypes are affected by AF in terms of long-term clinical outcomes because HFpEF is a heterogeneous syndrome with comorbidities such as coronary artery disease (CAD). In this study we determined the differential prognostic significance of AF in HFpEF patients according to CAD status.
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