Epicardial Application of Hydrogel with Amiodarone for Prevention of Postoperative Atrial Fibrillation in Patients After Coronary Artery Bypass Grafting

Targeted ablation of epicardial ganglionated plexi during cardiac surgery with pulsed field electroporation (NEURAL AF)

BACKGROUND

Modulation of the cardiac autonomic nervous system (ANS) is a promising adjuvant therapy in the treatment of atrial fibrillation (AF). In pre-clinical models, pulsed field (PF) energy has the advantage of selectively ablating the epicardial ganglionated plexi (GP) that govern the ANS. This study aims to demonstrate the feasibility and safety of epicardial ablation of the GPs with PF during cardiac surgery with a primary efficacy outcome of prolongation of the atrial effective refractory period (AERP).

METHODS

In a single-arm, prospective analysis, patients with or without a history of AF underwent epicardial GP ablation with PF during coronary artery bypass grafting (CABG). AERP was determined immediately pre- and post- GP ablation to assess cardiac ANS function. Holter monitors were performed to determine rhythm status and heart rate variability (HRV) at baseline and at 1-month post-procedure.

RESULTS

Of 24 patients, 23 (96%) received the full ablation protocol. No device-related adverse effects were noted. GP ablation resulted in a 20.7 ± 19.9% extension in AERP (P < 0.001). Post-operative AF was observed in 7 (29%) patients. Holter monitoring demonstrated an increase in mean heart rate (74.0 ± 8.7 vs. 80.6 ± 12.3, P = 0.01). There were no significant changes in HRV. There were no study-related complications.

CONCLUSIONS

This study demonstrates the safety and feasibility of epicardial ablation of the GP using PF to modulate the ANS during cardiac surgery. Large, randomized analyses are necessary to determine whether epicardial PF ablation can offer a meaningful impact on the cardiac ANS and reduce AF.

TRIAL REGISTRATION

Clinical trial registration: NCT04775264.

Designing Microneedle Patch for Prophylaxis of Postoperative Atrial Fibrillation

Postoperative atrial fibrillation (POAF) is a common complication following cardiac surgery, which often occurs within 30 postoperative days, especially peaking at 2-3 days. Antiarrhythmic medications such as amiodarone are recommended in clinical practice for the prophylaxis and treatment of POAF. However, conventional oral administration is hindered due to delayed drug action and high risks of systemic toxicity, and emerging localized delivery strategies suffer from a limited release duration (less than 30 days). Herein, we develop a microneedle (MN) patch for localized delivery of amiodarone to the atria in a "First Rapid and Then Sustained" dual-release mode. Specifically, this patch is composed of a needle array integrated with an amiodarone-loaded reservoir for a sustained and steady release for over 30 days; and an amiodarone-containing coating film deposited on the needle surface via the Langmuir-Blodgett technique for a rapid release at the first day. Upon this design, only one MN patch enables a higher drug accumulation in the atrial tissue at the first day than oral administration and simultaneously remains therapeutical levels for over 30 days, despite at a significantly reduced drug dosage (5.08 mg in total versus ∼10 mg per day), thereby achieving ideal preventive effects and safety in a rat model. Our findings indicate that this MN device provides a robust and efficient delivery platform for long-term prophylaxis of POAF.

Biomaterials for direct cardiac repair-A rapid scoping review 2012-2022

A plethora of biomaterials for heart repair are being tested worldwide for potential clinical application. These therapeutics aim to enhance the quality of life of patients with heart disease using various methods to improve cardiac function. Despite the myriad of therapeutics tested, only a minority of these studied biomaterials have entered clinical trials. This rapid scoping review aims to analyze literature available from 2012 to 2022 with a focus on clinical trials using biomaterials for direct cardiac repair, i.e., where the intended function of the biomaterial is to enhance the repair of the endocardium, myocardium, epicardium or pericardium. This review included neither biomaterials related to stents and valve repair nor biomaterials serving as vehicles for the delivery of drugs. Surprisingly, the literature search revealed that only 8 different biomaterials mentioned in 23 different studies out of 7038 documents (journal articles, conference abstracts or clinical trial entries) have been tested in clinical trials since 2012. All of these, intended to treat various forms of ischaemic heart disease (heart failure, myocardial infarction), were of natural origin and most used direct injections as their delivery method. This review thus reveals notable gaps between groups of biomaterials tested pre-clinically and clinically. STATEMENT OF SIGNIFICANCE: Rapid scoping review of clinical application of biomaterials for cardiac repair. 7038 documents screened; 23 studies mention 8 different biomaterials only. Biomaterials for repair of endocardium, myocardium, epicardium or pericardium. Only 8 different biomaterials entered clinical trials in the past 10 years. All of the clinically translated biomaterials were of natural origin.

Navigating the Incidence of Postoperative Arrhythmia and Hospitalization Length: The Role of Amiodarone and Other Antiarrhythmics in Prophylaxis

Antiarrhythmic drugs play a pivotal role in managing and preventing arrhythmias. Amiodarone, classified as a class III antiarrhythmic, has been used prophylactically to effectively prevent atrial fibrillation postoperatively in cardiac surgeries. However, there is a lack of consensus on the use of amiodarone and other antiarrhythmic drugs as prophylaxis to reduce the occurrence of all types of postoperative arrhythmias in cardiac and non-cardiac surgeries. A comprehensive PubMed query yielded 614 relevant papers, of which 52 clinical trials were analyzed. The data collection included the class of antiarrhythmics, timing or method of drug administration, surgery type, type of arrhythmia and its incidence, and hospitalization length. Statistical analyses focused on prophylactic antiarrhythmics and their respective reductions in postoperative arrhythmias and hospitalization length. Prophylactic amiodarone alone compared to placebo demonstrated a significant reduction in postoperative arrhythmia incidence in cardiac and non-cardiac surgeries (24.01%, p<0.0001), and it was the only treatment group to significantly reduce hospitalization length versus placebo (p = 0.0441). Prophylactic use of class 4 antiarrhythmics versus placebo also demonstrated a significant reduction in postoperative arrhythmia incidence (28.01%, p<0.0001), and while there was no significant statistical reduction compared to amiodarone (4%, p=0.9941), a lack of abundant data provides a case for further research on the prophylactic use of class 4 antiarrhythmics for this indication. Amiodarone prophylaxis remains a prime cornerstone of therapy in reducing postoperative arrhythmia incidence and hospitalization length. Emerging data suggests a need for a broader exploration of alternative antiarrhythmic agents and combination therapies, particularly class 4 antiarrhythmics, in both cardiac and non-cardiac surgeries. This meta-analysis depicts the effectiveness of amiodarone, among other antiarrhythmics, in postoperative arrhythmia incidence and hospitalization length reduction in cardiac and non-cardiac surgeries.

Cardiomyocyte-Targeting Peptide to Deliver Amiodarone

BACKGROUND

Amiodarone is underutilized due to significant off-target toxicities. We hypothesized that targeted delivery to the heart would lead to the lowering of the dose by utilizing a cardiomyocyte-targeting peptide (CTP), a cell-penetrating peptide identified by our prior phage display work.

METHODS

CTP was synthesized thiolated at the N-terminus, conjugated to amiodarone via Schiff base chemistry, HPLC purified, and confirmed with MALDI/TOF. The stability of the conjugate was assessed using serial HPLCs. Guinea pigs (GP) were injected intraperitoneally daily with vehicle (7 days), amiodarone (7 days; 80 mg/kg), CTP-amiodarone (5 days; 26.3 mg/kg), or CTP (5 days; 17.8 mg/kg), after which the GPs were euthanized, and the hearts were excised and perfused on a Langendorff apparatus with Tyrode's solution and blebbistatin (5 µM) to minimize the contractions. Voltage (RH237) and Ca2+-indicator dye (Rhod-2/AM) were injected, and fluorescence from the epicardium split and was captured by two cameras at 570-595 nm for the cytosolic Ca2+ and 610-750 nm wavelengths for the voltage. Subsequently, the hearts were paced at 250 ms with programmed stimulation to measure the changes in the conduction velocities (CV), action potential duration (APD), and Ca2+ transient durations at 90% recovery (CaTD90). mRNA was extracted from all hearts, and RNA sequencing was performed with results compared to the control hearts.

RESULTS

The CTP-amiodarone remained stable for up to 21 days at 37 °C. At ~1/15th of the dose of amiodarone, the CTP-amiodarone decreased the CV in hearts significantly compared to the control GPs (0.92 ± 0.05 vs. 1.00 ± 0.03 ms, p = 0.0007), equivalent to amiodarone alone (0.87 ± 0.08 ms, p = 0.0003). Amiodarone increased the APD (192 ± 5 ms vs. 175 ± 8 ms for vehicle, p = 0.0025), while CTP-amiodarone decreased it significantly (157 ± 16 ms, p = 0.0136), similar to CTP alone (155 ± 13 ms, p = 0.0039). Both amiodarone and CTP-amiodarone significantly decreased the calcium transients compared to the controls. CTP-amiodarone and CTP decreased the CaTD90 to an extent greater than amiodarone alone (p < 0.001). RNA-seq showed that CTP alone increased the expression of DHPR and SERCA2a, while it decreased the expression of the proinflammatory genes, NF-kappa B, TNF-α, IL-1β, and IL-6.

CONCLUSIONS

Our data suggest that CTP can deliver amiodarone to cardiomyocytes at ~1/15th the total molar dose of the amiodarone needed to produce a comparable slowing of CVs. The ability of CTP to decrease the AP durations and CaTD90 may be related to its increase in the expression of Ca-handling genes, which merits further study.

The Management of Postoperative Atrial Fibrillation (POAF): A Systematic Review

Postoperative atrial fibrillation (POAF) refers to new-onset atrial fibrillation (AF) that develops after surgery and is associated with an increased risk of mortality and thromboembolic events. The optimal management and treatment methods for POAF complications are not yet fully established. This systematic review aimed to evaluate the various treatment and management approaches currently available in terms of their suitability, efficacy, and side effects in handling POAF incidence post-surgery. Google Scholar and PubMed electronic databases were searched extensively for relevant articles examining the various management techniques currently used to manage POAF and published between 2018 and 2023. Data were collected on the type of surgery the patients underwent, POAF definition period, intervention, and outcome of interest. Following a systematic assessment guided by the inclusion criteria, 10 of the 579 studies retrieved were included in this study, and 293,417 POAF cases were recorded. Three of these studies used different rhythm control and rate control treatments to manage POAF cases, while seven studies used various anticoagulation therapies to manage POAF incidence. For asymptomatic patients within one to three days of surgery, rate control is sufficient to manage POAF, and routine rhythm control is not needed; rhythm control should be reserved for patients who develop complications such as hemodynamic instability. Anticoagulation was performed in patients whose POAF exceeded four days after surgery. Anticoagulation was associated with an increased risk of mortality, stroke, thromboembolic events, and major bleeding in patients who underwent coronary artery bypass graft (CABG) surgery. In contrast, in a few other studies, anticoagulation treatment led to improved outcomes in patients who developed POAF. A wide range of management methods are available for POAF after different types of surgery. However, there is only limited evidence to guide the clinical practice. The data available are mainly retrospective and insufficient to accurately evaluate the efficacy of the various management methods available for POAF. Future research should make efforts to standardize the treatment for this condition.

Conjugation of amiodarone to a novel cardiomyocyte cell penetrating peptide for potential targeted delivery to the heart

Modern medicine has developed a myriad of therapeutic drugs against a wide range of human diseases leading to increased life expectancy and better quality of life for millions of people. Despite the undeniable benefit of medical advancements in pharmaceutical technology, many of the most effective drugs currently in use have serious limitations such as off target side effects resulting in systemic toxicity. New generations of specialized drug constructs will enhance targeted therapeutic efficacy of existing and new drugs leading to safer and more effective treatment options for a variety of human ailments. As one of the most efficient drugs known for the treatment of cardiac arrhythmia, Amiodarone presents the same conundrum of serious systemic side effects associated with long term treatment. In this article we present the synthesis of a next-generation prodrug construct of amiodarone for the purpose of advanced targeting of cardiac arrhythmias by delivering the drug to cardiomyocytes using a novel cardiac targeting peptide, a cardiomyocyte-specific cell penetrating peptide. Our in vivo studies in guinea pigs indicate that cardiac targeting peptide-amiodarone conjugate is able to have similar effects on calcium handling as amiodarone at 1/15th the total molar dose of amiodarone. Further studies are warranted in animal models of atrial fibrillation to show efficacy of this conjugate.

Cardiomyocyte Targeting Peptide to Deliver Amiodarone

Background

Amiodarone is underutilized due to significant off-target toxicities. We hypothesized that targeted delivery to the heart would lead to lowering of dose by utilizing a cardiomyocyte targeting peptide (CTP), a cell penetrating peptide identified by our prior phage display work.

Methods

CTP was synthesized thiolated at the N-terminus, conjugated to amiodarone via Schiff base chemistry, HPLC purified and confirmed with MALDI/TOF. Stability of the conjugate was assessed using serial HPLCs. Guinea pigs (GP) were injected intraperitoneally daily with vehicle (7 days), amiodarone (7 days; 80mg/Kg), CTP-amiodarone (5 days;26.3mg/Kg), or CTP (5 days; 17.8mg/Kg), after which GPs were euthanized, hearts excised, perfused on a Langendorff apparatus with Tyrode's solution and blebbistatin (5μM) to minimize contractions. Voltage (RH237) and Ca 2+ -indicator dye (Rhod-2/AM) were injected, fluorescence from the epicardium split and focused on two cameras capturing at 570-595nm for cytosolic Ca 2+ and 610-750nm wavelengths for voltage. Subsequently, hearts were paced at 250ms with programmed stimulation to measure changes in conduction velocities (CV), action potential duration (APD) and Ca 2+ transient durations at 90% recovery (CaTD 90 ). mRNA was extracted from all hearts and RNA sequencing performed with results compared to control hearts.

Results

CTP-amiodarone remained stable for up to 21 days at 37°C. At ∼1/15 th of the dose of amiodarone, CTP-amiodarone decreased CV in hearts significantly compared to control GPs (0.92±0.05 vs. 1.00±0.03m/s, p=0.0007), equivalent to amiodarone alone (0.87±0.08ms, p=0.0003). Amiodarone increased APD (192±5ms vs. 175±8ms for vehicle, p=0.0025), while CTP-amiodarone decreased it significantly (157±16ms, p=0.0136) similar to CTP alone (155±13ms, p=0.0039). Both amiodarone and CTP-amiodarone significantly decreased calcium transients compared to controls. CTP-amiodarone and CTP decreased CaTD 90 to an extent greater than amiodarone alone (p<0.001). RNA-seq showed that CTP alone increased the expression of DHPR and SERCA2a, while decreasing expression of proinflammatory genes NF-kappa B, TNF-α, IL-1β, and IL-6.

Conclusions

Our data suggests that CTP can deliver amiodarone to cardiomyocytes at ∼1/15 th the total molar dose of amiodarone needed to produce comparable slowing of CVs. The ability of CTP to decrease AP durations and CaTD 90 may be related to its increase in expression of Ca-handling genes, and merits further study.

Polyelectrolyte Microcapsules-A Promising Target Delivery System of Amiodarone with the Possibility of Prolonged Release

Atrial fibrillation is one of the most common cardiac arrhythmias. Pharmacological preparations are used for treatment to control heart rate and rhythm. Amiodarone is one of these highly effective preparations, but, at the same time, it has significant toxicity and nonspecific accumulation in tissues. The drug delivery system based on polyelectrolyte microcapsules is one of the solutions. For this purpose, we compared different encapsulation methods of amiodaron: monoammonium salt of glycyrrhizic acid (Am:MASGA) complex (molar ratio 1:8). The concentration of amiodarone was determined by spectrophotometric methods at 251 nm. It has been shown that the co-precipitation method allows capturing 8% of Am:MASGA by CaCO₃ microspherulites, which is not sufficient for the long-acting drug. The adsorption method allows encapsulating more than 30% of Am:MASGA into CaCO₃ microspherulites and polyelectrolyte microcapsules CaCO₃(PAH/PSS)₃, but, at the same time, an insignificant amount of substance is released into the incubation medium. The development of delivery and long-acting drug system based on such methods are not inexpedient. The most appropriate encapsulation method of Am:MASGA is the adsorption method into polyelectrolyte microcapsules with complex interpolyelectrolyte structure (PAH/PSS)₃. Such a type of PMC adsorbed about 50% of the initial amount of the substance and 25-30% of Am:MASGA was released into the medium after 115 h of incubation. The adsorption of Am:MASGA by polyelectrolyte microcapsules has electrostatic nature as evidenced by the acceleration of the release by 1.8 times as ionic strength increases.

Effectiveness of intra-operative topical amiodarone for prevention of postcardiac surgery new-onset atrial fibrillation: A review of current evidence

BACKGROUND

Postoperative atrial fibrillation (POAF) is one of the most common complications following cardiac surgery and is associated with increased morbidity. Intraoperative topical amiodarone application on epicardial tissue has been shown to reduce systemic concentrations while maintaining therapeutic myocardial concentrations, thereby, lowering the risk of extracardiac adverse effects associated with oral and intravenous amiodarone therapy. However, the efficacy and safety of topical amiodarone in preventing POAF is unclear.

OBJECTIVES

This study summarizes the clinical studies to-date that have investigated the efficacy and safety of topical amiodarone administration in preventing POAF following cardiac surgery.

METHODS

A database search was conducted using Medline, Embase, and Cochrane Library to identify relevant studies. Abstracts were screened and data were extracted from relevant full-text articles that met the inclusion and exclusion criteria.

RESULTS

The search returned four studies with variable findings on the effect of topical amiodarone therapy on the incidence of POAF, cardiac effects, extracardiac effects, and hospital length of stay.

CONCLUSION

Prophylactic topical application of amiodarone may be effective and safe for preventing post-operative new-onset atrial fibrillation. Further investigation is required to evaluate the efficacy and safety of topical amiodadrone therapy before it can be widely integrated into current practice.

Local Use of Hydrogel with Amiodarone in Cardiac Surgery: Experiment and Translation to the Clinic

The objective of this study was to study the use of the hydrogel biopolymer based on sodium alginate ("Colegel") with a drug substance-amiodarone-for the prevention of postoperative atrial fibrillation (POAF) in cardiac surgery. The experimental part of the study was performed on 46 rabbits. Five groups were formed: in the first group, the dose of amiodarone in hydrogel was 1 mg; in the second group-3 mg; in the third group-6 mg; in the fourth group, hydrogel was used without amiodarone; in the fifth group, 60 mg amiodarone was administered intravenously. The animals from each group were removed from the experiment for the pathomorphological study of the heart after 3, 7 and 14 days. The studied endpoints were: the heart rate control; the development of the blockades of the conduction system of the heart; and the development of inflammation according to laboratory pathomorphological studies. The translational clinical part involved a randomized clinical trial which included 60 patients, with an average age of 62 ± 8.5 years. All patients were randomized into two groups: the study group (n = 30, with the application of amiodarone hydrogel) and the control group (n = 30, without the application of amiodarone hydrogel). The dose of amiodarone in the hydrogel material was 60 mg for all patients. The heart rhythm was monitored during 5 days. The primary endpoint was the development of POAF. Secondary endpoints were: the dynamics of heart rate; the duration of the QT and PQ intervals; the development of blockades of the cardiac conduction system; as well as the dynamics of AST and ALT. According to the results of the experimental part, it was found that the method of the local epicardial delivery of amiodarone by the hydrogel material was safe. Hydrogel with amiodarone is effective for reducing the heart rate in the animal experiment in comparison to the control group and the group with the intravenous administration of the drug. The optimal dose of amiodarone in hydrogel was 1 mg per 1 kg. According to the results of the clinical part, it was found that the method of the local epicardial delivery of amiodarone as a hydrogel material proved its safety. Hydrogel with amiodarone at a dose of 60 mg was effective in preventing POAF in patients after coronary artery bypass grafting (CABG) operations in comparison to the control group (p < 0.001). The age and procedure of application of the amiodarone gel were significantly associated with POAF (p = 0.009 and p = 0.011, respectively). The use of hydrogel with amiodarone reduced the probability of developing POAF 18.9-fold. The method of the local epicardial delivery of amiodarone in the form of a hydrogel material is safe. The use of hydrogel with amiodarone after CABG reduced the probability of developing POAF.