Comparison of efficacy of pharmacological cardioversion with antazoline and propafenone versus electrical cardioversion in atrial fibrillation during cryoablation.

Introduction: Antazoline with propafenone may be an alternative to electrical cardioversion (ECV) in restoring sinus rhythm in patients with atrial fibrillation (AF), including during balloon cryoablation. Aim: To compare the efficacy of antazoline with propafenone and ECV in restoring and maintaining sinus rhythm at discharge in patients with AF during cryoablation with special regard to type of AF. Material and methods: The study retrospectively analyzed 196 patients who underwent elective cryoablation. Eighty-nine patients who developed AF in the perioperative period were selected as the study group (32 women and 57 men). The study group was divided into two groups - 46 (51.7%) patients were given pharmacological cardioversion with 70 mg of propafenone and 100 or 200 mg of antazoline, whereas the other 43 (48.3%) patients underwent ECV. Results: There were no statistically significant differences between the groups regarding: left atrial area, left atrium diameter, right atrial area and right atrium diameter. In the overall population, ECV was more effective than antazoline with propafenone therapy (31 [72.1%] vs. 20 [43.5%]; p = 0.01). A similar relationship was demonstrated in patients with persistent AF (13 [59.1%] vs. 3 [12.5%]; p = 0.002). There was no significant difference in the group of patients with paroxysmal AF (18 (85.6%) vs. 17 (77.3%); p = 0.7). Conclusions: In AF during the cryoablation procedure ECV appears to be more effective in restoring and maintaining sinus rhythm at discharge than antazoline with propafenone in the general AF patient population, especially in patients with persistent AF.

Del Nido vs. Cold Blood Cardioplegia for High-Risk Isolated Coronary Artery Bypass Grafting in Patients with Reduced Ventricular Function.

INTRODUCTION: The evidence for using del Nido cardioplegia protocol in high-risk patients with reduced ejection fraction undergoing isolated coronary surgery is insufficient. METHODS: The institutional database was searched for isolated coronary bypass procedures. Patients with ejection fraction < 40% were selected. Propensity matching (age, sex, infarction, number of grafts) was used to pair del Nido (Group 1) and cold blood (Group 2) cardioplegia patients. Investigation of biomarker release, changes in ejection fraction, mortality, stroke, perioperative myocardial infarction, composite endpoint (major adverse cardiac and cerebrovascular events), and other perioperative parameters was performed. RESULTS: Matching allowed the selection of 45 patient pairs. No differences were noted at baseline. After cross-clamp release, spontaneous sinus rhythm return was observed more frequently in Group 1 (80% vs. 48.9%; P=0.003). Troponin values were similar in both groups 12 and 36 hours after surgery, as well as creatine kinase at 12 hours. A trend favored Group 1 in creatine kinase release at 36 hours (median 4.9; interquartile range 3.8-9.6 ng/mL vs. 7.3; 4.5-17.5 ng/mL; P=0.085). Perioperative mortality, rates of myocardial infarction, stroke, or major adverse cardiac and cerebrovascular events were similar. No difference in postoperative ejection fraction was noted (median 35.0%; interquartile range 32.0-38.0% vs. 35.0%; 32.0-40.0%; P=0.381). There was a trend for lower atrial fibrillation rate in Group 1 (6.7% vs. 17.8%; P=0.051). CONCLUSION: The findings indicate that del Nido cardioplegia provides satisfactory protection in patients with reduced ejection fraction undergoing coronary bypass surgery. Further prospective trials are required.

Long-term bio-functional performance of a novel, self-positioning balloon expandable transcatheter biological aortic valve system in the ovine aortic banding model.

BACKGROUND: The aim of the study was to evaluate bio-functionality of a novel, proprietary balloon-expandable biological transcatheter aortic valve implantation (TAVI) system (InFlow, CardValve Consortium, Poland) in an ovine model of aortic banding. METHODS: Surgical ascending aorta banding was created in 21 sheep. Two weeks later, 18 biological valves were implanted within the model using 15-16 F InFlow TAVI systems and carotid cut-down approach. Follow-up transthoracic echocardiography was performed at 30, 90, and 180-day. At designated time, animals were euthanized and valves harvested for analysis. RESULTS: All sheep survived the banding procedure. There were 4 (22%) procedure related deaths within a 7-day period. During the observation an additional 2 sheep died. In one, the valve dislocated after the procedure - the animal was excluded. Two animals completed 30-day follow up, five 90-day follow-up and four terminal follow-up of 180 days. Valves examined via transesophageal echocardiography showed proper hemodynamic parameters without evidence of structural valve deterioration. The maximum and average flow gradients at 180 days were 31.4 (23.3-37.7) and 17.5 (13.1-20.2) mmHg, respectively. There was one case of moderate insufficiency and no case of perivalvular leaks. By histopathology, there were no inflammation, thrombosis, nor calcifications in any tested valves at long-term follow-up. Neointimal coverage of stent struts increased with time from basal part in "early" groups to nearly 3/4 of stent length in the 180-day group. The pannus tissue showed maturation that increased with time with no stenotic "collar" visible in orthotopically implanted valves. CONCLUSIONS: The study showed good hemodynamic performance, durability and biocompatibility of the novel biological THV.

Determinants of Inadequate Cardioprotection in Adult Patients with Left Ventricular Dysfunction.

BACKGROUND: Perioperative cardioprotection is essential for achieving satisfactory clinical outcomes in heart failure patients. It is important to understand the factors affecting perioperative cardioprotection. METHODS: The institutional database was searched for patients with reduced ejection fraction (EF, < 40%) who underwent surgery with cardioplegia-induced arrest. Patients were divided into del Nido cardioplegia (DN) and cold blood cardioplegia (CB) groups. The relationships between age, preoperative blood parameters, creatinine, cross-clamp time (CCT), extracorporeal circulation time (ECT), and postoperative troponin values at 12 hours or deterioration of EF (≥5%) were evaluated. Baseline characteristics, operative parameters, and outcomes were analyzed. RESULTS: There were 508 patients with reduced EF (331 DN and 177 CB). In the entire cohort, anemic patients had greater troponin values (p = 0.004) as well as in the DN group (p = 0.002). However, this was not detected in the CB group (flat regression line; p = 0.674). Patients with high leukocyte values had greater troponin release (entire cohort: p < 0.001; DN group: p < 0.001; CB group: steep regression line with p = 0.042). Longer CCT and ECT were associated with greater troponin release (entire cohort; both groups) and greater risk of fall in EF. In a direct comparison, fewer patients had significant deterioration of EF in the DN group than CB group (3.9 vs. 11.9%; p < 0.001). CONCLUSION: The use of CB cardioplegia may be beneficial in anemic patients, whereas the use of DN cardioplegia may be beneficial for expected long CCT and high leukocytosis.

Long-term outcomes of the Coordinated Care Program in Patients after Myocardial Infarction (KOS-MI).

BACKGROUND: The Coordinated Care in Myocardial Infarction Program (KOS-MI) was introduced to improve prognosis for patients after myocardial infarction (MI). The program includes complete revascularization followed by unrestricted access to rehabilitation, electrotherapy and cardiac care. AIM: The aim of this study was to assess major adverse cardiac and cerebrovascular events (MACCE) of patients enrolled in the KOS-MI at 3-year follow-up. METHODS: This is a retrospective, multicenter registry of patients treated for MI. Study group (KOS-MI) of 963 patients was compared to the control group (standard of care) of 1009 patients. At 3-year follow-up MACCE including death, MI, stroke and repeated revascularization were reported. Additionally, hospitalization due to heart failure (HF) was analyzed. Propensity score matching (PSM) was utilized for group baseline characteristics adjustment. RESULTS: Patients in the KOS-MI group were younger (65 vs. 68; P < 0.001), mostly men (70% vs. 62.9%; P < 0.001), admitted with ST-elevation myocardial infarction (STEMI) (44.6% vs. 36.2%; P < 0.001). Patients in the control group had more comorbidities and were admitted more often with non ST-elevation myocardial infarction (63.8% vs. 55.4%; P < 0.001) and acute HF (5.1% vs. 2.7%; P = 0.007). Following PSM 530 well matched pairs were selected. At three years (92.3% follow-up completeness), the relative risk reduction was: 25% in MACCE (P = 0.008), 38% in mortality (P = 0.008), 29% in repeated revascularization(P = 0.04) and 28% (P = 0.0496) in hospitalization for HF in the KOS-MI group. CONCLUSIONS: The combination of contemporary invasive techniques, complete revascularization, cardiac rehabilitation and ambulatory care included in the KOS-MI Program improves long-term prognosis of patients after MI up to 3-year follow-up.

Safety and feasibility of minimally invasive coronary artery bypass surgery early after drug-eluting stent implantation due to acute coronary syndrome.

BACKGROUND: The evidence on performing minimally invasive coronary artery surgery early after drug-eluting stent (DES) implantation due to acute coronary syndrome (ACS) is limited. AIM: The study aimed to determine the safety and feasibility of this approach. METHODS: This registry included 115 (78% male) patients treated from 2013 to 2018, who underwent non-left anterior descending (LAD) percutaneous coronary intervention (PCI) due to ACS with contemporary DES implantation (39% diagnosed with myocardial infarction at baseline), followed by endoscopic atraumatic coronary artery bypass (EACAB) surgery within 180 days, after temporary P2Y12 inhibitor discontinuation. Primary composite endpoint of MACCE (major adverse cardiac and cerebrovascular events), defined as death, myocardial infarction (MI), cerebrovascular incident, and repeat revascularization was evaluated in long-term follow-up. The follow-up was collected via a telephone survey and in line with National Registry for Cardiac Surgery Procedures. RESULTS: The median (interquartile range [IQR]) time interval separating both procedures was 100.0 (62.0-136.0) days. Median (IQR) follow-up duration was 1338.5 (753.0-2093.0) days and was completed for all patients with regard to mortality. Eight patients (7%) died; 2 (1.7%) had a stroke; 6 (5.2%) suffered from MI, and 12 (10.4%) required repeat revascularization. Overall, the incidence of MACCE was 20 (17.4%). CONCLUSIONS: EACAB is a safe and feasible method of LAD revascularization in patients who received DES for ACS within 180 days before surgery despite early dual antiplatelet therapy discontinuation. The adverse event rate is low and acceptable.

Del Nido versus cold blood cardioplegia in adult patients with impaired ejection fraction undergoing valvular and complex heart surgery.

BACKGROUND: There is sparse evidence on the efficacy of del Nido cardioplegia in high-risk patients with reduced ejection fraction undergoing valvular or complex heart surgery, and further investigation is required. METHODS: An institutional registry was searched for patients who underwent valvular or complex heart surgery and had an ejection fraction <40%. Subjects who received del Nido cardioplegia (DNC) and cold blood cardioplegia (CBC) were selected. Propensity matching was performed with age, gender, and number of conducted procedures as matching criteria. A comparative analysis was performed on primary endpoints of the troponin rise and changes in ejection fraction (EF). A composite endpoint of a troponin rise of ≥20× baseline or fall of EF≥5% was assessed in a multivariate analysis. Other perioperative complications are reported. RESULTS: One hundred patients from the DNC group were matched to the 100 patients in the CBC group. There were no differences between groups at baseline. Postoperatively, lower troponin values were observed in the DNC group at 12 hours (median; IQR: 523.2;349.1-740.4 pg/mL vs. 787.6;443.6-1689.0 pg/mL; P=0.016) and 36 hours (median; IQR: 426.1;337.2-492.1 pg/mL vs. 653.7;398.8-1737.5 pg/mL; P=0.044). Fewer patients in the DNC group had a fall in EF≥5% (7% vs. 16%; P=0.046). The multivariable analysis did not reveal a significant predictor of composite endpoint. CONCLUSIONS: In patients with impaired contractility undergoing valvular and complex procedures, the use of del Nido cardioplegia as an alternative to cold blood cardioplegia is associated with lower troponin release and improved preservation of ejection fraction.

Incidence and course of acute coronary syndrome cases after the first wave of the COVID-19 pandemic.

BACKGROUND: The collateral damage caused by the COVID-19 pandemic affected cardiovascular disease patients, mainly acute coronary syndrome (ACS) cases. Additionally, lockdown caused treatment-related concerns and reluctance to seek medical help, factors that can delay treatment. AIM: We aimed to analyze the incidence and course of ACS after the first COVID-19 wave. METHODS: The report is based on a multi-institutional registry of 10 interventional cardiology departments. ACS patient data were gathered from June to October 2020, i.e. in the period following the first lockdown in Poland (March 30-May 31, 2020) and compared with the corresponding 2019 timeframe. RESULTS: Patients (2801 and 2620) hospitalized for ACS in 2019 and 2020 (June-October) represented 52.8% and 57.9% of coronary artery disease admissions, respectively. In 2020 vs. 2019, more cases of arterial hypertension (80.2% vs. 71.5%; P <0.001), diabetes (32.7% vs. 28.2%; P <0.001) hyperlipidemia (53.2% vs. 49.8%; P = 0.01), and smoking history (29.5% vs. 25.8%; P = 0.003) were detected. Median troponin and cholesterol values, as well as glycemia, were higher in 2020. Patients were more likely to undergo percutaneous treatment (91.2% vs. 87.5%; P <0.001) and were less often referred for surgery (3.7% vs. 4.9%; P = 0.03). No differences in deaths from repeat myocardial infarction, stroke, and/or composite endpoint (major adverse cardiac and cerebrovascular events [MACCE]) were noted. However, suffering from ACS in 2020 (June-October) was a risk factor for mortality based on multivariable analysis. CONCLUSIONS: The COVID-19 pandemic affected ACS patient profile, course of treatment, and increased risk for mortality.

Actual status and future directions of cardiac telerehabilitation.

Telerehabilitation (TR) was developed to achieve the same results as would be achieved by the standard rehabilitation process and to overcome potential geographical barriers and staff deficiencies. This is especially relevant in periodic crisis situations, including the recent COVID-19 pandemic. Proper execution of TR strategy requires both well-educated staff and dedicated equipment. Various studies have shown that TR may have similar effects to traditional rehabilitation in terms of clinical outcomes and may also reduce total healthcare costs per participant, including rehospitalization costs. However, as with any method, TR has its advantages and disadvantages, including a lack of direct contact or prerequisite, rudimentary ability of the patients to handle mobile devices, among other competencies. Herein, is a discussion of the current status of TR, focusing primarily on cardiac TR, describing some technical/organizational and legal aspects, highlighting the indications, examining cost-effectiveness, as well as outlining possible future directions.

The impact of first wave of the SARS-CoV-2 2019 pandemic in Poland on characteristics and outcomes of patients hospitalized due to stable coronary artery disease.

BACKGROUND: An investigation of baseline characteristics, treatment, and outcomes in patients with stable coronary disease after the first wave of the severe acute respiratory syndrome coronavirus 2 (SARS- -CoV-2) pandemic may provide valuable data and is beneficial for public health strategy in upcoming years. METHODS: A multi-institutional registry, including 10 cardiology departments, was searched for patients admitted from June 2020 to October 2020. The baseline characteristics (age, gender, symptoms, comorbidities), treatment (non-invasive, invasive, surgical), and hospitalization outcome (mortality, myocardial infarction, stroke, composite endpoint - major adverse cardiac and cerebrovascular events [MACCE]) were evaluated. The comparison was made to parameters presented by patients from the same timeframe in 2019 (June-October). Multivariable analysis was performed. RESULTS: Number of hospitalized stable patients following lockdown was lower (2498 vs. 1903; p < 0.0001). They were younger (68.0 vs. 69.0; p < 0.019), more likely to present with hypertension (88.5% vs. 77.5%; p < 0.0001), diabetes (35.7% vs. 31.5%; p = 0.003), hyperlipidemia (67.9% vs. 55.4%; p < 0.0001), obesity (35.8% vs. 31.3%; p = 0.002), and more pronounced symptoms (Canadian Cardiovascular Society [CCS] III and CCS class IV angina: 30.4% vs. 26.5%; p = 0.005). They underwent percutaneous treatment more often (35.0% vs. 25.9%; p < 0.0001) and were less likely to be referred for surgery (3.7% vs. 4.9%; p = 0.0001). There were no significant differences in hospitalization outcome. New York Heart Association (NYHA) class IV for heart failure was a risk factor for both mortality and MACCE in multivariate analysis. CONCLUSIONS: The SARS-CoV-2 2019 pandemic affected the characteristics and hospitalization course of stable angina patients hospitalized following the first wave. The hospitalization outcome was similar in the analyzed time intervals. The higher prevalence of comorbidities raises concern regarding upcoming years.

Use of del Nido cardioplegia in acute coronary syndrome cases with decreased ejection fraction.

BACKGROUND: There has been increasing interest in using del Nido cardioplegia in adult cardiac surgery. However, there is limited evidence for its efficacy in patients with acute coronary syndrome and reduced ejection fraction. METHODS: This study examined patients with decreased ejection fraction (EF < 40%) who were hospitalized due to acute coronary syndrome and received either del Nido (DN) or cold blood cardioplegia (CB). The patients were matched based on age, gender, myocardial infarction at baseline, and number of conducted surgical procedures. An analysis was conducted on postoperative biomarker release (high-sensitivity troponin T and isoenzyme creatine kinase-MB (CK-MB)), changes in myocardial contractility and perioperative outcomes. RESULTS: 62 pairs of patients with similar baseline characteristics were selected. 51.6% of pairs underwent isolated coronary artery bypass grafting, while 48.4% underwent a complex procedure. Postoperative troponin values did not differ significantly at 12 h (median (IQR): 606.7 (381.4-974.8) pg/mL vs. 552 (231.8-1579.5) pg/mL; p = 0.913), nor did CK-MB (median (IQR): 24.3 (12.6-45.5) ng/mL vs. 23.7 (12.3-49.8) ng/mL; p = 0.972). The postoperative EF was similar between groups (median (IQR): 30% (30-35%) vs. 34% (30-38%); p = 0.323). No difference in perioperative mortality, myocardial infarction, stroke, or composite endpoint was noted. In a multivariate analysis, the cardioplegia protocol did not affect biomarker release or changes in ejection fraction. The first stage of acute kidney injury was more frequent in the CB group (28.5% vs. 9.7%, p = 0.033). CONCLUSIONS: Both del Nido and cold blood cardioplegia provide adequate cardioprotection in patients with acute coronary syndrome with decreased ejection fraction.

One-stage hybrid coronary revascularization for the treatment of multivessel coronary artery disease- Periprocedural and long-term results from the "HYBRID-COR" feasibility study.

Background: The constant growth of interest in hybrid coronary artery revascularization (HCR) is apparent. Yet, few studies report outcomes of the one-stage HCR. Consequently, the status of such procedures is not adequately supported in clinical guidelines. The aim of this study was to report the safety, feasibility, and long term-outcomes of the one-stage HCR. Methods and results: Patients were enrolled in the prospective one-stage hybrid coronary revascularization program (HYBRID-COR). They underwent a one-stage hybrid revascularization procedure while on double antiplatelet therapy (DAPT) with Ticagrelor: endoscopic atraumatic coronary artery bypass grafting (EACAB) for revascularization of the left anterior descending (LAD) artery and percutaneous intervention in non-LAD arteries with contemporary drug-eluting stents. The composite primary endpoint included MACCE (major adverse cardiac and cerebrovascular events: death, myocardial infarction, stroke, and repeated revascularization) in long-term observation. The study cohort consisted of 30 patients (68% male) with stable coronary artery disease (26.7%) and unstable angina (73.3%). Procedural success was 100%. No death, myocardial infarction (MI), or stroke were observed in the perioperative period. One patient (3.3%) required chest revision and blood transfusion due to surgical bleeding. Kidney injury was noted in two patients (6.6%). In a long-term follow-up (median; IQR: 4.25; 2.62-4.69 years), two patients (6.6%) underwent repeated revascularization and one patient (3.3%) died due to MI. The overall primary endpoint rate was 9.9%. Conclusion: One-stage hybrid revascularization, on DAPT, is a feasible, safe, and efficient way of achieving complete revascularization in selected patients. The complication rate is low and acceptable. Further randomized trials are required.

6-Month Evaluation of a Transcatheter Aortic Valve (Myval) in a Novel Ovine, Supra-Aortic Banding Model.

The aim of the study was to evaluate a balloon expandable transcatheter heart valve (THV) system (Myval) at 6-month follow-up in ovine banding model. Eleven THV systems were implanted via carotid approach. There were 2 procedure-related deaths and 2 premature deaths. At 6 months all valves that completed follow-up (n = 7) were functional, with no significant regurgitation, calcification, thrombi, or vegetation. Mean pressure gradient was 21.9 ± 11 mm Hg, maximum velocity = 3.3 ± 1 m/s, and ejection fraction was 53.3 ± 6%. Myval THV showed optimal hemodynamic performance and biocompatibility.

Temporal, biomechanical evaluation of a novel, transcatheter polymeric aortic valve in ovine aortic banding model.

Objectives: The aim of the study is to evaluate the functionality, durability, and temporal biocompatibility of a novel, balloon-expandable polymeric transcatheter heart valve (ATHV) system (InFlow, CardValve Consortium, Poland). Along with expanding TAVI indications, the demand for new transcatheter valves is increasing. Methods: A surgical ascending aortic banding model was created in 20 sheep. Two weeks later, 16 sheep were implanted with ATHV systems (15-16F). Three animals were euthanized after a 30-day follow-up, four animals after a 90-day follow-up, and six animals after a 180-day follow-up. A follow-up transthoracic echocardiography (TTE) was performed. Results: There was one procedure-related (6,25%) and two model-related deaths (12,5%; banding site calcification with subsequent infection originating externally from banding). TTE revealed the flow gradients (max/average) of 30,75/17,91; 32,57/19,21; and 21,34/10,63 mmHg at 30, 90, and 180 days, respectively. There were two cases of low-degree regurgitation after 180 days with no perivalvular leak observed. Histopathological analysis showed no valve degeneration at terminal follow-up with optimal healing. Small thrombi were present at the aortic wall adjacent to the base of the leaflets, and between the aortic wall and the stent in most of the valves; however, leaflets remained free from thrombi in all cases. Scanty calcifications of leaflets were reported in three animals evaluated 180 days after implantation. Conclusion: This preclinical study in the aortic banding model showed good hemodynamic performance, durability, and biocompatibility of the novel ATHV. Furthermore, regulatory studies with longer follow-ups are warranted.

Microcrystalline paclitaxel-coated balloon for revascularization of femoropopliteal artery disease: Three-year outcomes of the randomized BIOPAC trial.

The aim of the BIOPAC trial was to determine long-term safety and efficacy of a novel microcrystalline paclitaxel-coated balloon (mcPCB) with a biocompatible polymer as an excipient in the treatment of occlusive femoropopliteal lesions. In this first-in-human prospective controlled randomized trial, 66 patients with femoropopliteal, symptomatic (Rutherford stages 2B to 5) occlusive arterial disease were randomized to either mcPCB (study group) or POBA (plain old balloon angioplasty) (control group) on a 1:1 basis. Late lumen loss (LLL) at 6 months was the primary endpoint of the study and serious adverse events (SAE: death, amputation, repeated revascularization) were considered a composite secondary endpoint. Routine angiography was scheduled for all study subjects at 6-month follow-up; outpatient appointments were scheduled at 12 and 36 months after intervention. At 6 months, the LLL was 63% lower in the mcPCB group compared to the POBA group (0.52 ± 1.2 vs 1.39 ± 1.1 mm; psup < 0.01). Binary restenosis occurred in 23% vs 52% of patients (p = 0.02). At 3 years, the prevalence of SAE was significantly lower in the mcPCB group (33.3 vs 63.3%; p = 0.02), which mainly resulted from a twofold reduction in target vessel revascularization rate (28.6 vs 59.3%; p = 0.02). The difference in mortality was nonsignificant (7.4 vs 14.3%; p = 0.42). Patients with mcPCB were less symptomatic and less likely to adhere to secondary prevention measures. In this pivotal trial, a novel mcPCB proved superior to POBA concerning LLL at 6-month follow-up, and SAE at 12 months. This result was sustained up to 3 years. There was no difference between groups regarding mortality. ClinicalTrials.gov Identifier: NCT02145065.

Drug-likeness of linear pentamidine analogues and their impact on the hERG K+ channel - correlation with structural features.

This work presents drug-likeness and the cardiotoxicity profiles of six potent pentamidine analogs 1-6 and three new compounds 7-9 as chemotherapeutics for therapy of Pneumocystis jiroveci pneumonia. A combination of experimental and computational approaches was used in the cardiotoxicity examination. The hERG trafficking and functionality of the hERG currents were tested by western blot analyses, immunofluorescent staining procedures, and patch-clamp electrophysiological assays. Cardiotoxicity combined with blocking the hERG K+ channel was predicted, and then simulated by docking to the CSM-TM model 732 protein. Location of pentamidines in the proximity of Leu622, Thr623, Ser649, Tyr652, Ala653, and Phe656, and the high energies of interactions were in accordance with probable blocking of the hERG channel. However, in the biochemical experiments, no significant changes in I hERG densities and a minor effect on hERG maturation were observed. Predicted metabolic transformation of pentamidines with S atoms in the aliphatic linker leads to oxidation of one S atom, but those with the phenyl sulfanilide moiety can be oxidized to chinones. The tested pentamidines characterized by the presence of sulfur atoms or sulfanilide groups, have favorable drug-likeness parameters and are promising lead structures in the development of new potent chemotherapeutics against PJP.

Pentamidine analogs as inhibitors of [(3)H]MK-801 and [(3)H]ifenprodil binding to rat brain NMDA receptors.

The anti-protozoal drug pentamidine is active against opportunistic Pneumocystis pneumonia, but in addition has several other biological targets, including the NMDA receptor (NR). Here we describe the inhibitory potencies of 76 pentamidine analogs at 2 binding sites of the NR, the channel binding site labeled with [(3)H]MK-801 and the [(3)H]ifenprodil binding site. Most analogs acted weaker at the ifenprodil than at the channel site. The spermine-sensitivity of NR inhibition by the majority of the compounds was reminiscent of other long-chain dicationic NR blockers. The potency of the parent compound as NR blocker was increased by modifying the heteroatoms in the bridge connecting the 2 benzamidine moieties and also by integrating the bridge into a seven-membered ring. Docking of the 45 most spermine-sensitive bisbenzamidines to a recently described acidic interface between the N-terminal domains of GluN1 and GluN2B mediating polyamine stimulation of the NR revealed the domain contributed by GluN1 as the most relevant target.

Probing the relationship between anti-Pneumocystis carinii activity and DNA binding of bisamidines by molecular dynamics simulations.

The anti-Pneumocystis carinii activity of 13 synthetic pentamidine analogs was analyzed. The experimental differences in melting points of DNA dodecamer 5'-(CGCGAATTCGCG)2-3' complexes (ΔTm), and in the biological activity measured using ATP bioluminescence assay (IC50) together with the theoretical free energy of DNA-ligand binding estimated by the proposed computational protocol, showed that the experimental activity of the tested pentamidines appeared to be due to the binding to the DNA minor groove with extended AT sequences. The effect of heteroatoms in the aliphatic linker, and the sulfonamide or methoxy substituents on the compound inducing changes in the interactions with the DNA minor groove was examined and was correlated with biological activity. In computational analysis, the explicit solvent approximation with the discrete water molecules was taken into account, and the role of water molecules in the DNA-ligand complexes was defined.

In vitro screening of pentamidine analogs against bacterial and fungal strains.

A series of linear pentamidine analogs exhibiting low cytotoxicity, active against Pneumocystis carinii, were evaluated for in vitro activities against bacterial and fungal strains. The majority of the tested bis-amidines exhibited marked activities against Gram-positive strains. In view of the fact that the highest potency was found for 1,5-bis(4-amidinophenoxy)-3-thiapentane dihydrochloride 1j with the S atom in the middle of the aliphatic linker, four new pentamidines bearing S atoms were synthesized and also evaluated against MRSA strains. N,N'-Dialkylated pentamidines with S atoms in the linker are the promising lead structures for antimicrobials development.

Analogs of pentamidine as potential anti-Pneumocystis chemotherapeutics.

A series of 20 pentamidine analogs were prepared using 2 general Schemes that evaluated heteroatoms, sulfobenzene and alkanediamide groups in the aliphatic linker and methoxy substituents attached to the benzene rings for efficacy against the fungal pathogen, Pneumocystis carinii in an ATP bioassay. All but one of the 20 bisamidines reduced the ATP content of the P. carinii over the 72 h of the assay period. The highest activities were associated with the lack of methoxy groups and the presence of the O, N and S heteroatoms. Activity (IC(50)) for compounds 1, 5, 6, 10 ranged from 1.1 to 2.13 µM. The compound 11 with similar activity (1.33 µM), bears a sulfobenzene group at a nitrogen in the aliphatic linker. The alkanediamide-linked bisbenzamidines showed a moderate inhibition of ATP. Generally, the inclusion of a heteroatom in the aliphatic linker and absence of methoxy groups at the benzene rings were associated with higher activities in this assay. Of note, most of the compounds had little to no cytotoxicity in mammalian cell cultures. Although not quite as potent as other pentamidine derivatives, these compounds hold promise for decreased side effects within the mammalian host.