Opportunities and Barriers to Rural Telerobotic Surgical Health Care in 2021: Report and Research Agenda from a Stakeholder Workshop.

Background: There are well-recognized challenges to delivering specialty health care in rural settings. These challenges are particularly evident for specialized surgical health care due to the lack of trained operators in rural communities. Telerobotic surgery could have a significant impact on the rural-urban health care gap, but thus far, the promise of this method of health care delivery has gone unrealized. With the increasing adoption of telehealth over the past year, along with the maturation of telecommunication and robotic technologies over the past 2 decades, a reappraisal of the opportunities and barriers to widespread implementation of telerobotic surgery is warranted. Here we report the outcome of a rural telerobotic stakeholder workshop to explore modern-day issues critical to the advancement of telerobotic surgical health care. Materials and Methods: We assembled a multidisciplinary stakeholder panel to participate in a 2-day Rural Telerobotic Surgery Stakeholder Workshop. Participants had diverse expertise, including specialty surgeons, technology experts, and representatives of the broader telerobotic health care ecosystem, including economists, lawyers, regulatory consultants, public health advocates, rural hospital administrators, nurses, and payers. The research team reviewed transcripts from the workshop with themes identified and research questions generated based on stakeholder comments and feedback. Results: Stakeholder discussions fell into four general themes, including (1) operating room team interactions, (2) education and training, (3) network and security, and (4) economic issues. The research team then identified several research questions within each of these themes and provided specific research strategies to address these questions. Conclusions: There are still important unanswered questions regarding the implementation and adoption of rural telerobotic surgery. Based on stakeholder feedback, we have developed a research agenda along with suggested strategies to address outstanding research questions. The successful execution of these research opportunities will fill critical gaps in our understanding of how to advance the widespread adoption of rural telerobotic health care.

Exploring telerobotic cardiac catheter ablation in a rural community hospital: A pilot study.

Background: Telerobotic surgery could improve access to specialty procedures such as cardiac catheter ablation in rural and underserved regions in the United States and worldwide. Advancements in telecommunications, internet infrastructure, and surgical robotics are lowering the technical hurdles for this future healthcare delivery paradigm. Nonetheless, important questions remain regarding the safe implementation of telerobotic surgery in rural community hospital settings. Objective: The purpose of this study was to pilot test a system and methods to explore telerobotic cardiac catheter ablation in a rural community hospital setting. Methods: We assembled a portable preclinical telerobotic catheter ablation system from commercial-grade components using third-party vendors. We then carried out 4 telerobotic surgery simulations with an urban surgeon and a rural community hospital operating room (OR) team spanning a distance of more than 2000 miles. Two challenge scenarios were incorporated into the simulations, including loss of network connection and cardiac perforation with subsequent life-threatening tamponade physiology. An ethnographic analysis was then performed. Results: Interviews and observations suggested that rural OR teams readily adapt to the telesurgery context. However, participant perceptions of team trust, communication, and emergency management were significantly altered by the remote location of the surgeon. In addition, most participants believed the OR team would have been better equipped for the challenges had they received formal training or had prior experience with the procedure being simulated. Conclusion: We demonstrate the utility and feasibility of a system and methods for studying specialty telerobotic surgery in a rural hospital OR setting.

Catheter ablation of atrial fibrillation results in significant QTc prolongation in the postoperative period.

BACKGROUND: The corrected QT interval (QTc) is a measure of ventricular repolarization time, and a prolonged QTc increases risk for malignant ventricular arrhythmias. Pulmonary vein isolation (PVI) may increase QTc but its effects have not been well studied. OBJECTIVE: Determine the incidence, risk factors, and outcomes of patients presenting for PVI in sinus and atrial fibrillation with postoperative QTc prolongation in a large cohort. METHODS: We performed a single-center retrospective study of consecutive atrial fibrillation ablations. QTc durations using Bazett correction were obtained from electrocardiograms at different postoperative intervals and compared to preoperative QTc. We studied clinical outcomes including clinically significant ventricular arrhythmia and death. A multivariable model was used to identify factors associated with clinically significant QTc prolongation, defined as ΔQTc ≥60 ms or new QTc duration ≥500 ms. RESULTS: A total of 352 PVIs were included in this study. We observed a statistically significant increase in mean QTc compared to baseline (446.3 ± 37.8 ms) on postoperative day (POD)0 (471.7 ± 38.2 ms, P < .001) and at POD1 (456.5 ± 35.0 ms, P < .001). There was no significant difference at 1 month (452.4 ± 33.5 ms, P = .39) and 3 months (447.3 ± 40.0 ms, P = .78). Sixty-six patients (19.2%) developed ΔQTc ≥60 ms or QTc ≥500 ms on POD0, with 4.1% persisting past 90 days. Female sex (odds ratio [OR] = 1.82, 95% confidence interval [CI] =1.01-3.29, P = .047) and history of coronary artery disease (OR = 2.16, 95% CI = 1.03-4.55, P = .042) were independently predictive of QTc prolongation ≥500 ms or ΔQTc ≥60 ms. There were no episodes of clinically significant ventricular arrhythmia or death attributable to arrhythmia. CONCLUSION: QTc duration increased significantly immediately post-PVI and returned to baseline by 1 month. PVI did not provoke significant ventricular arrhythmias in our cohort.

Management of Arrhythmias After Heart Transplant: Current State and Considerations for Future Research.

Orthotropic heart transplantation remains the most effective therapy for patients with end-stage heart failure, with a median survival of ≈13 years. Yet, a number of complications are observed after orthotropic heart transplantation, including atrial and ventricular arrhythmias. Several factors contribute to arrhythmias, such as autonomic denervation, effect of the surgical technique, acute and chronic rejection, and transplant vasculopathy among others. To minimize risk of future arrhythmias, the bicaval technique and minimizing ischemic time are current surgical standards. Sinus node dysfunction is the most common indication for early (within 30 days) pacemaker implantation, whereas atrioventricular block incidence increases as time from transplant increases. Atrial fibrillation can occur in the first few weeks following transplantation but is uncommon in the long term unless secondary to a precipitant such as acute rejection. The most common atrial arrhythmias are atrial flutters, which are mainly typical, but atypical circuits can be observed such as those that involve the remnant donor atrium in regions immediately adjacent to the atrioatrial anastomosis suture line. Choosing the appropriate pharmacological therapy requires careful consideration due to the potential interaction with immunosuppressive agents. Despite historical concerns, adenosine is effective and safe at reduced doses if administered under cardiac monitoring. Catheter ablation has emerged as an effective treatment strategy for symptomatic supraventricular tachycardias, including ablation of atypical flutter circuits. Cardiac allograft vasculopathy is an important risk factor for sudden cardiac death, yet the role of prophylactic implantable cardioverter-defibrillator implant for sudden death prevention is unclear. Current indications for implantable cardioverter-defibrillator implantation are as in the nontransplant population. A number of questions for future research are posed.

Safety and Effectiveness of Hydroxychloroquine and Azithromycin Combination Therapy for Treatment of Hospitalized Patients with COVID-19: A Propensity-Matched Study.

INTRODUCTION: We sought to determine the effectiveness and safety of hydroxychloroquine-azithromycin (HCQ-AZM) therapy in hospitalized patients with COVID-19. METHODS: This was a retrospective cohort study of 613 patients hospitalized (integrated health system involving three hospitals) for RT-PCR-confirmed COVID-19 infection between March 1, 2020 and April 25, 2020. Intervention was treatment with HCQ-AZM in hospitalized patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Outcomes of interest were in-hospital all-cause mortality, cardiovascular mortality, pulseless electrical activity (PEA) arrest, non-lethal arrhythmias, and length of hospital stay. Secondary measures included in-hospital corrected QT (QTc) interval parameters and serum biomarkers levels. RESULTS: Propensity-matched groups were composed of 173 patients given HCQ-AZM and 173 matched patients who did not receive treatment. There was no significant difference in in-hospital mortality (odds ratio [OR] 1.52; 95% confidence interval [CI] 0.80-2.89; p = 0.2), PEA arrest (OR 1.68, CI 0.68-4.15; p = 0.27), or incidence of non-lethal arrhythmias (10.4% vs. 6.8%; p = 0.28). Length of hospital stay (10.5 ± 7.4 vs. 5.8 ± 6.1; p < 0.001), peak CRP levels (252 ± 136 vs. 166 ± 124; p < 0.0001), and degree of QTc interval prolongation was higher for the HCQ-AZM group (28 ± 32 vs. 9 ± 32; p < 0.0001), but there was no significant difference in incidence of sustained ventricular arrhythmias (2.8% vs. 1.7%; p = 0.52). HCQ-AZM was stopped in 10 patients because of QT interval prolongation and 1 patient because of drug-related polymorphic ventricular tachycardia. CONCLUSION: In this propensity-matched study, there was no difference in in-hospital mortality, life-threatening arrhythmias, or incidence of PEA arrest between the HCQ-AZM and untreated control groups. QTc intervals were longer in patients receiving HCQ-AZM, but only one patient developed drug-related ventricular tachycardia.

QT interval and arrhythmic safety of hydroxychloroquine monotherapy in coronavirus disease 2019.

BACKGROUND: Observational studies have suggested increased arrhythmic and cardiovascular risk with the combination use of hydroxychloroquine (HCQ) and azithromycin in patients with coronavirus disease 2019 (COVID-19). OBJECTIVE: The arrhythmic safety profile of HCQ monotherapy, which remains under investigation as a therapeutic and prophylactic agent in COVID-19, is less established and we sought to evaluate this. METHODS: In 245 consecutive patients with COVID-19 admitted to the University of Washington hospital system between March 9, 2020, and May 10, 2020, we identified 111 treated with HCQ monotherapy. Patients treated with HCQ underwent a systematic arrhythmia and QT interval surveillance protocol including serial electrocardiograms (ECG) (baseline, following second HCQ dose). The primary endpoint was in-hospital sustained ventricular arrhythmia or arrhythmic cardiac arrest. Secondary endpoints included clinically significant QTc prolongation. RESULTS: A total of 111 patients with COVID-19 underwent treatment with HCQ monotherapy (mean age 62 ± 16 years, 44 women [39%], serum creatinine 0.9 [interquartile range 0.4] mg/dL). There were no instances of sustained ventricular arrythmia or arrhythmic cardiac arrest. In 75 patients with serial ECGs, clinically significant corrected QT (QTc) prolongation was observed in a minority (n = 5 [7%]). In patients with serial ECGs, there was no significant change in the QTc interval in prespecified subgroups of interest, including those with prevalent cardiovascular disease or baseline use of renin-angiotensin-aldosterone axis inhibitors. CONCLUSIONS: In the context of a systematic monitoring protocol, HCQ monotherapy in hospitalized COVID-19 patients was not associated with malignant ventricular arrhythmia. A minority of patients demonstrated clinically significant QTc prolongation during HCQ therapy.

Leadless Pacemakers: Recent and Future Developments.

PURPOSE OF REVIEW: Leadless pacemakers were developed to reduce complications associated with transvenous pacemaker implant and long-term follow-up. Since initial market release, however, there have been registry and single-center reports documenting improvements in implant technique, reduced complication rates, and new patient populations studied. RECENT FINDINGS: Most studies have demonstrated a further reduction in complication rates and safe implant in those on continuous anticoagulation. Perforation rates are decreasing but still occur and risk factors include BMI < 20 kg/m2, age ≥ 85 years, females, history of heart failure, indication not including atrial fibrillation, and chronic lung disease. Device infections are exceedingly rare, even in those undergoing infected transvenous devices at the same time. For appropriate patients, leadless pacing is a safe and reasonable option, especially if atrial-based sensing or pacing is not needed. Future iterations may include VDD pacing, atrial pacing, dual-chamber pacing, biventricular pacing, and device-device communication.

Management of S-ICD lead in a patient requiring sternotomy.

In patients who have had a prior subcutaneous ICD implanted, a sternotomy can be safely performed without the need for replacement of the ICD. Appropriate tools and closure technique during reimplantation are essential for this to be a possibility.

Increased risk of hematoma with uninterrupted warfarin in patients undergoing implantation of subcutaneous implantable cardioverter defibrillator.

BACKGROUND: The perioperative management of anticoagulation with the use of subcutaneous implantable cardioverter-defibrillator (S-ICD) implantation is still evolving. OBJECTIVE: The purpose of this study was to assess whether it is safe to perform S-ICD implantation with uninterrupted warfarin. METHODS: This is a multi-center retrospective review of patients undergoing S-ICD implantation between October 1, 2012 and June 30, 2017. Forty-eight patients underwent successful S-ICD implantation during the study period. The most common indication for implantation was primary prevention of sudden cardiac death. In 23 (47.9%) patients, warfarin was continued without any interruption. In 25 (52.1%) patients, warfarin was interrupted prior to implantation. The incidence of clinically significant lateral pocket hematoma was compared in the two groups. RESULTS: The mean international normalized ratio was 2.0 ± 0.4 in the uninterrupted group and 1.4 ± 0.4 for the interrupted group. A total of seven patients developed a hematoma at the lateral pocket. No patient developed a hematoma at the parasternal pockets. Six patients in the uninterrupted group (26.1%) and one patient in the interrupted group (0.04%) developed a significant lateral pocket hematoma (P = .04). The concomitant use of dual antiplatelet therapy did not increase the risk of hematoma. There was no significant difference between HASBLED and CHA2 DS2 VASc scores between the groups. None of the patients with a hematoma developed infection or required hematoma evacuation. CONCLUSIONS: The uninterrupted use of warfarin in the perioperative period of S-ICD implantation is associated with an increased risk of lateral pocket hematoma.

TpTe and TpTe/QT: novel markers to predict sudden cardiac death in ESRD? / TpTe e TpTe/QT: novos marcadores para prever morte súbita cardíaca na DRT?

ABSTRACT Introduction: Reliable markers to predict sudden cardiac death (SCD) in patients with end stage renal disease (ESRD) remain elusive, but echocardiogram (ECG) parameters may help stratify patients. Given their roles as markers for myocardial dispersion especially in high risk populations such as those with Brugada syndrome, we hypothesized that the Tpeak to Tend (TpTe) interval and TpTe/QT are independent risk factors for SCD in ESRD. Methods: Retrospective chart review was conducted on a cohort of patients with ESRD starting hemodialysis. Patients were US veterans who utilized the Veterans Affairs medical centers for health care. Average age of all participants was 66 years and the majority were males, consistent with a US veteran population. ECGs that were performed within 18 months of dialysis initiation were manually evaluated for TpTe and TpTe/QT. The primary outcomes were SCD and all-cause mortality, and these were assessed up to 5 years following dialysis initiation. Results: After exclusion criteria, 205 patients were identified, of whom 94 had a prolonged TpTe, and 61 had a prolonged TpTe/QT interval (not mutually exclusive). Overall mortality was 70.2% at 5 years and SCD was 15.2%. No significant difference was observed in the primary outcomes when examining TpTe (SCD: prolonged 16.0% vs. normal 14.4%, p=0.73; all-cause mortality: prolonged 55.3% vs. normal 47.7%, p=0.43). Likewise, no significant difference was found for TpTe/QT (SCD: prolonged 15.4% vs. normal 15.0%, p=0.51; all-cause mortality: prolonged 80.7% vs. normal 66.7%, p=0.39). Conclusions: In ESRD patients on hemodialysis, prolonged TpTe or TpTe/QT was not associated with a significant increase in SCD or all-cause mortality.

RESUMO Introdução: Marcadores confiáveis para predizer morte súbita cardíaca (MSC) em pacientes com doença renal terminal (DRT) permanecem elusivos, mas os parâmetros do ecocardiograma (ECG) podem ajudar a estratificar os pacientes. Devido a seus papéis como marcadores para a dispersão miocárdica, especialmente em populações de alto risco, como aquelas com síndrome de Brugada, nós hipotetizamos que o intervalo pico da onda T ao final da onda T (TpTe) e TpTe/QT são fatores de risco independentes para MSC na DRT. Métodos: Revisão retrospectiva do prontuário foi realizada em uma coorte de pacientes com DRT iniciando a hemodiálise. Os pacientes eram veteranos de guerra americanos que utilizavam os centros médicos do Veterans Affairs para atendimento médico. A idade média de todos os participantes foi de 66 anos e a maioria era do sexo masculino, consistente com uma população veterana dos EUA. ECGs que foram realizados dentro de 18 meses após o início da diálise, e foram avaliados manualmente para TpTe e TpTe/QT. Os desfechos primários foram MSC e mortalidade por todas as causas, e estes foram avaliados até 5 anos após o início da diálise. Resultados: Após o critério de exclusão, foram identificados 205 pacientes, dos quais 94 com TpTe prolongado e 61 com intervalo TpTe/QT prolongado (não mutuamente exclusivo). A mortalidade geral foi de 70,2% em 5 anos e a MSC foi de 15,2%. Nenhuma diferença significativa foi observada nos desfechos primários ao se avaliar o TpTe (MSC: prolongado 16,0% versus normal 14,4%, p = 0,73; mortalidade por todas as causas: prolongado 55,3% vs. normal 47,7%, p = 0,43). Da mesma forma, nenhuma diferença significativa foi encontrada para TpTe/QT (MSC: prolongado 15,4% vs. normal 15,0%, p = 0,51; mortalidade por todas as causas: prolongado 80,7% vs. normal 66,7%, p = 0,39). Conclusões: Em pacientes com insuficiência renal terminal em hemodiálise, TpTe ou TpTe/QT prolongados não foram associados a um aumento significativo da morte súbita ou mortalidade por todas as causas.

TpTe and TpTe/QT: novel markers to predict sudden cardiac death in ESRD?

INTRODUCTION: Reliable markers to predict sudden cardiac death (SCD) in patients with end stage renal disease (ESRD) remain elusive, but electrocardiogram (ECG) parameters may help stratify patients. Given their roles as markers for myocardial dispersion especially in high risk populations such as those with Brugada syndrome, we hypothesized that the Tpeak to Tend (TpTe) interval and TpTe/QT are independent risk factors for SCD in ESRD. METHODS: Retrospective chart review was conducted on a cohort of patients with ESRD starting hemodialysis. Patients were US veterans who utilized the Veterans Affairs medical centers for health care. Average age of all participants was 66 years and the majority were males, consistent with a US veteran population. ECGs that were performed within 18 months of dialysis initiation were manually evaluated for TpTe and TpTe/QT. The primary outcomes were SCD and all-cause mortality, and these were assessed up to 5 years following dialysis initiation. RESULTS: After exclusion criteria, 205 patients were identified, of whom 94 had a prolonged TpTe, and 61 had a prolonged TpTe/QT interval (not mutually exclusive). Overall mortality was 70.2% at 5 years and SCD was 15.2%. No significant difference was observed in the primary outcomes when examining TpTe (SCD: prolonged 16.0% vs. normal 14.4%, p=0.73; all-cause mortality: prolonged 55.3% vs. normal 47.7%, p=0.43). Likewise, no significant difference was found for TpTe/QT (SCD: prolonged 15.4% vs. normal 15.0%, p=0.51; all-cause mortality: prolonged 80.7% vs. normal 66.7%, p=0.39). CONCLUSIONS: In ESRD patients on hemodialysis, prolonged TpTe or TpTe/QT was not associated with a significant increase in SCD or all-cause mortality.

Outcomes With Novel Oral Anticoagulants in Obese Patients who Underwent Electrical Cardioversion for Atrial Tachyarrhythmias.

The efficacy of novel oral anticoagulants (NOACs) in severely obese patients is uncertain as volume of distribution is related to weight, and few such patients were enrolled in the pivotal trials. As the month after direct-current cardioversion (DCCV) for atrial fibrillation and atrial flutter is a high-risk period for stroke, we sought to evaluate the safety of performing DCCV in obese patients on NOAC. All patients who underwent DCCV after ≥3 weeks of NOAC or therapeutic warfarin treatment without a previous transesophageal echocardiogram over a 3-year period at a single center were included. Obesity groups were defined as normal (body mass index [BMI] < 25), overweight (BMI 25 to <30), class 1 obesity (BMI 30 to <35), class 2 obesity (BMI 35 to <40), and class 3 or severe obesity (BMI ≥ 40). The primary end point was stroke at 30days. Of 761 patients, 73 were severely obese, 78 class 2 obese, 197 class 1 obese, 254 overweight, and 159 in the normal weight group. Average age 66.4 ± 10.3years and 32.5% women. Mean CHA2DS2-VASc score was 2.6 ± 1.6, and 78.9% were on NOACs with no differences in groups. There were no strokes in the severely obese group, and 1 each in class 2 obesity and normal weight (p = 0.3). In conclusion, there was a low rate of stroke in all weight classes after DCCV in patients taking NOACs and warfarin. NOAC use in severely obese patients who underwent DCCV appears safe even in the absence of transesophageal echocardiogram.

Dialytic interval and the timing of electrocardiographic screening for subcutaneous cardioverter-defibrillator placement in chronic hemodialysis patients.

BACKGROUND: Hemodialysis (HD) patients have a high risk of sudden death but limited vascular access and high complication rates from transvenous implantable cardioverter-defibrillators (ICDs). Subcutaneous ICDs (S-ICD) may be an alternative, but dynamic ECG changes may result in inappropriate shocks. This study aims to define the screen failure rate for S-ICD in patients pre- and post-HD. METHODS: ECG waveforms were obtained using electrodes mimicking the S-ICD sensing vectors in an unselected test group of chronic HD patients and a control group of ICD-eligible non-dialysis patients. Participants passed screening if their QRS and T-waves fit within the screening template in supine and standing positions in any lead. Test group participants were screened before and after HD and control group patients were screened at two separate time points. HD patients were stratified into the four following groups: (A) passed screening before and after HD, (B) failed screening before but passed after HD, (C) passed screening before but failed after HD, and (D) failed screening before and after HD. Patients in group A passed the screening for ICD implantation, and patients in groups B, C, and D failed the screening for ICD implantation. Control patients were similarly classified by pass/fail status at the two assessment points. RESULTS: Of the 76 patients enrolled, 51 were HD patients and 25 were controls. Of the 51 HD patients, 43 (84%) were in group A, four participants (8%) were in group B, one (2%) was in group C, and three participants (6%) were in group D. There were no differences in any of the clinical or demographic variables between the pass and fail test HD groups. None of the 25 controls failed the screening at either time point (p = 0.047 vs HD patients). CONCLUSIONS: Overall, HD patients were more likely to fail S-ICD screening compared to non-HD patients (16 v 0%, p = 0.047) and are more likely to do so prior to HD. Patients on HD should be screened at multiple time points around the dialytic interval to reduce the risk of inappropriate shocks.

Heart Failure and Sudden Cardiac Death.

The Centers for Diseases Control and Prevention estimates that 5.7 million adults in the United States suffer from heart failure and 1 in 9 deaths in 2009 cited heart failure as a contributing cause. Almost 50% of patients who are diagnosed with heart failure die within 5 years of diagnosis. Cardiovascular disease is a public health burden. The prognosis of patients with heart failure has improved significantly. However, the risk for death remains high. Managing sudden death risk and intervening appropriately with primary or secondary prevention strategies are of paramount importance.

Subcutaneous implantable cardioverter defibrillator for dialysis patients: a strategy to reduce central vein stenoses and infections.

Central venous stenosis is a common complication of the transvenous leads associated with an implantable cardioverter defibrillator (ICD). Although epicardial leads have been reported to bypass this complication, their placement is much more invasive than the subcutaneous ICDs (SICDs) and requires the services of a cardiothoracic surgeon. Recent data have demonstrated successful defibrillation using an SICD. In this report, we present 4 long-term hemodialysis patients treated successfully with an SICD. 3 patients received the device for primary prevention of sudden cardiac death (cardiomyopathy with low ejection fraction). The patient in the fourth case had a prolonged QT interval and received the device for secondary prevention. 3 patients had an arteriovenous fistula, whereas 1 patient was dialyzing with a tunneled dialysis catheter. Insertion of an SICD is a minimally invasive procedure. By virtue of leaving the venous system untouched, this approach might offer the advantage of reduced risk of central venous stenosis and infection over an endocardial ICD with transvenous leads. SICD is not experimental; it has been approved by the US Food and Drug Administration and is currently being used in the United States and Europe.

A TACTful reappraisal of chelation therapy in cardiovascular disease.

Atherosclerotic cardiovascular disease (CVD) is highly prevalent and, despite therapeutic advances, remains a leading cause of morbidity and mortality. Many patients with CVD seek additional alternative therapies when symptoms are not controlled with evidence-based therapies. Although its therapeutic efficacy is unproven, chelation therapy with ethylenediamine tetra acetic acid (EDTA) is increasingly being used in patients with CVD. Early studies of chelation in atherosclerotic CVD provided the basis for the randomized Trial to Assess Chelation Therapy (TACT), in which chelation with disodium EDTA was compared with placebo in patients who had experienced a myocardial infarction. Here, we discuss the results, limitations, and implications of TACT in the context of other studies in the field. We believe that the findings from TACT are not robust and do not marshal evidence in support of the potential clinical use of chelation therapy for CVD, with the potential exception of certain high-risk cohorts such as patients with diabetes mellitus. Therefore, chelation is unlikely to become a widely-accepted approach until additional data are available.

CYP2C9 polymorphism studies in the Saudi population.

OBJECTIVE: To determine the prevalence of CYP2C9 polymorphism in normal Saudis (controls), in Saudi patients with venous thrombosis, in patients requiring low dose warfarin (study group) for anticoagulation, and to compare our results to those from other populations. METHODS: Blood from the control and study groups was collected from November 2001 to November 2008. The DNA was extracted, stored at -70°C and later tested for the CYP2C9 polymorphism using established methods. Clinical data were collected through direct interview, chart review, and the Saudi Thrombosis and Familial Thrombophilia Registry. All individuals consented. RESULTS: The prevalence of CYP2C9 polymorphisms in the Saudi population was similar to Caucasians and higher than Asian and African. The control (n=670) and patients with venous thrombosis (n=110) groups showed similar prevalence of the normal wild type CYP2C9 and the 2 polymorphisms tested (CYP2C9*2 and CYP2C9*3). The group that required low dose warfarin (n=25) showed significantly higher CYP2C9 polymorphism, required 40% less warfarin and had a higher rate of bleeding (5% versus 1.8%). CONCLUSION: The prevalence of the abnormal polymorphism in the Saudi population of 35.5% is similar to that in Caucasians. Patients with the CYP2C9 polymorphism required 40% less warfarin and had more serious bleeds.

Antiproliferative mechanisms of the flavonoids 2,2'-dihydroxychalcone and fisetin in human prostate cancer cells.

We have previously demonstrated the antiproliferative effect of two flavonoids-2,2'-dihydroxychalcone (DHC), a novel synthetic flavonoid, and fisetin, a naturally occurring flavonol-in prostate cancer cells. In this study, we further examine the mechanisms of these compounds on survival and proliferation pathways. DHC and fisetin (1-50 microM) caused a dose-dependent reduction in viability, a concomitant increase in apoptosis in PC3 cells at 72 h, and a decrease in clonogenic survival at 24 h treatment. DHC was considerably more potent than fisetin in these cytotoxicity assays. The mechanism of accelerated cellular senescence was not activated by either compound in PC3 or lymph node carcinoma of the prostate (LNCaP) cells. Gene expression alterations in PC3 and LNCaP cells treated with 15 muM DHC and 25 microM fisetin for 6 to 24 h were determined by oligonucleotide array. Amongst the most highly represented functional categories of genes altered by both compounds was the cell cycle category. In total, 100 cell cycle genes were altered by DHC and fisetin including 27 genes with key functions in G2/M phase that were downregulated by both compounds. Other functional categories altered included chromosome organization, apoptosis, and stress response. These results demonstrate the multiple mechanisms of antitumor activity of DHC and fisetin in prostate cancer cells in vitro.