Glycoprotein IIb/IIIa receptor targeted PET/CT imaging: a novel diagnostic tool for detecting bioprosthetic valve thrombosis

Background/Introduction

Bioprosthetic valve thrombosis (BPVT) is an important clinical entity eventually following both bioprosthetic surgical and transcatheter aortic valve replacement. Although dynamic contrast-enhanced 4D-MDCT has improved the diagnosis of BPVT, more sensitive and pathology-specific non-invasive imaging tools are lacking. Recently, the glycoprotein IIb/IIIa receptor targeted, elarofiban-derived PET/CT imaging radiotracer [18F]GP1 has been successfully used for visualization of acute venous and arterial thrombi.

Purpose

We hypothesized that [18F]GP1 PET/CT imaging is suitable to detect BPVT.

Methods

In this proof-of-concept study, patients after bioprosthetic aortic valve replacement with symptomatic, severe hemodynamic valve dysfunction and confirmed hypoattenuated leaflet thickening (HALT) in dynamic 4D-MDCT were offered to participate in compassionate use examinations to undergo PET/CT imaging with the investigational [18F]GP1 PET tracer at baseline and after a 12-week course of therapeutic oral anticoagulation.

Results

This case series reports on three patients after aortic valve replacement. Two patients with symptomatic, obstructive BPVT as confirmed by echocardiography and 4D-MDCT fulfilled specified criteria and underwent [18F]GP1 PET/CT imaging. [18F]GP1 PET/CT clearly distinguished between blood pool activity and thrombotic foci. Clot-to-blood ratios at baseline were 8.2 and 4.5, respectively. A 12-week trial of therapeutic oral anticoagulation was associated with a regression of mean transprosthetic pressure gradient and reversal of HALT. Follow-up 4D-MDCT corroborated thrombus resolution in both patients. Correspondingly, [18F]GP1 PET/CT imaging demonstrated decreased tracer uptake in both patients. Clot-to-blood ratio at follow-up visit decreased to 1.2 and 2.9, respectively. While absent tracer uptake was seen in patient #1, residual tracer uptake was observed in patient #2 suggestive of ongoing platelet aggregation. One asymptomatic SAVR patient was examined with [18F]GP1 PET/CT for a different compassionate use and no thrombotic foci were detected on the leaflets.

Conclusions

[18F]GP1 PET/CT is a novel imaging technique in patients with obstructive BPVT. In a head-to-head comparison we show that [18F]GP1 PET/CT may have incremental diagnostic value over dynamic contrast-enhanced 4D-MDCT alone by detection of sites of ongoing platelet aggregation at the molecular level. [18F]GP1 PET/CT may serve as a novel, highly sensitive tool to overcome some limitations of current diagnostic imaging modalities for detecting BPVT and may prove useful for the monitoring and guidance of therapeutic interventions.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): Life Molecular Imaging provided material for [18F]GP1 radiolabeling free of charge as part of an ongoing research collaboration.

Impact of impaired renal function on kinetics of high-sensitive troponin I (hs-cTnI) following cardiac surgery

Background

Renal insufficiency might result in increased levels of cardiac troponin due to decreased elimination. Hence, the diagnostic utility of hs-cTnI might be lower in patients with impaired renal function. There is only scarce data on kinetics of high-sensitivity cardiac troponin I (hs-cTnI) following cardiac surgery with regard to renal function.

Purpose

The aim of this study was to assess the impact of impaired renal function on the kinetics of hs-cTnI following cardiac surgery differentiating between patients with and without postoperative myocardial infarction (PMI) and to analyze the prognostic value of hs-cTnI elevations in patients with impaired renal function.

Methods

We performed a retrospective analysis of all adult patients (>18 years) who underwent cardiac surgery at our hospital between Jan, 1st 2013 and May, 1st 2019.

Serial measurements of high-sensitive cardiac troponin I (hs-cTnI) were assessed from baseline up to 48 hours after surgery. Renal function was assessed based on estimated glomerular filtration rate (GFR) using the Modification of Diet in Renal Disease (MDRD) formula with impaired renal function defined by GFR <60 ml/min. Postoperative myocardial infarction was defined by new vessel occlusion on angiography. Predictors of long-term all-cause mortality were assessed by cox regression analysis.

Results

A total of 14,465 patients were included (51.4% underwent coronary artery bypass grafting (CABG), 39.4% had valvular procedures and 9.2% thoracic aortic procedures).

Levels of hs-cTnI were higher in patients with impaired renal function in the overall collective (figure 1). However, in patients with postoperative myocardial infarction levels of hs-cTnI did not differ with regard to renal function (figure 2).

Cox regression analysis showed postoperative elevation of hs-cTnI to be a significant predictor of long-term all-cause mortality over a median follow-up of 3.0 years regardless of baseline kidney function (Hazards ratio 1.67, 95% Confidence interval [1.46–1.91], p<0.001).

Conclusion

Renal function had an impact on postoperative hs-cTnI kinetics only in patients with an uneventful postoperative course. In patients with postoperative myocardial infarction kinetics of hs-cTnI were not affected by baseline renal function. Moreover, elevated hs-cTnI levels were a significant predictor of all-cause mortality regardless of baseline renal function.

Funding Acknowledgement

Type of funding sources: None.

Which way in? The necessity of multiple approaches to transcatheter valve therapy

TAVI (transcatheter aortic valve implantation) is a less invasive treatment of the stenotic aortic valve while avoiding midline sternotomy and cardiopulmonary bypass. A crimped biological valve on a self-expanding or balloonexpandable stent is inserted antegradely or retrogradely under fluoroscopy, and deployed on the beating heart. Among the worldwide TAVI programs, many different concepts have been established for the choice of the access site. Whether retrograde or antegrade TAVI should be considered the superior approach is matter of an ongoing debate. The published literature demonstrates safety of all techniques if performed within a dedicated multidisciplinary team. Since there is no data providing evidence if one approach is superior to another, we conclude that an individualized patient-centered decision making process is most beneficial, taking advantage of the complementarity of the different access options. The aim of this article is to give an overview of the current practice of access techniques for transcatheter based valve treatment and to outline the respective special characteristics.

Sirolimus-associated infertility: case report and literature review of possible mechanisms

The mammalian-target-of-rapamycin/mTOR-inhibitor sirolimus as a component of the immunosuppressive strategy after solid organ transplantation is effective at preventing allograft rejection. However, recent reports indicate that sirolimus is associated with altered sex hormone levels and impaired sperm quality parameters. Herein, we report on a case of sirolimus-associated infertility in a young male heart-lung transplant recipient and provide a detailed synopsis of potential mechanisms by which sirolimus may negatively influence spermatogenesis. Testicular immunohistochemistry, the course of sex hormone and sperm quality parameters of our patient support the hypothesis that mTOR might act as an important key regulator in the reproductive system. Fortunately, due to withdrawal of sirolimus as part of the maintenance, immunosuppression improved sperm quality and sex hormone parameters could be observed. Recently, these improvements even resulted in a spontaneous pregnancy of the patient's wife more than 1 year after the drug was withdrawn. In our view, oligospermia as a possible and at least partly reversible side-effect of mTOR inhibitors has to be taken into consideration, particularly, when administrated to young male patients.

Cardiac transplantation in a 14-yr-old patient with mitochondrial encephalomyopathy

We report a rare case of a successful cardiac transplantation in a patient suffering from cardiomyopathy and complex mitochondrial disease. The patient presented with severe heart failure and malignant ventricular arrhythmias requiring implantation of a defibrillator and advanced medical treatment. The patient was listed for urgent heart transplantation and received a donor heart after 36 days. One yr post-operatively, the patient has completely recovered.

Successful single lung fontan operation in 2 children: case reports

We report on 2 children, aged 3 and 4 years, with single ventricle physiology who underwent Fontan operation in the presence of a single right lung successfully with good midterm outcome. Therefore, the absence of one lung is not a contraindication for a Fontan palliation in selected patients with optimal hemodynamics.

Phase III adjuvant trial of concurrent epirubicin/taxane vs. sequential epirubicin/cyclophosphamide followed by taxane for node positive breast cancer

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Background: This study evaluates whether concurrent epirubicin/taxane (ET) improves disease-free survival (DFS) at 3 yrs compared to the sequential combination of epirubicin/cyclophosphamide followed by a taxane (EC>T) in pts with operable node (+) breast cancer. Methods: Eligible pts were randomized to receive either ET (E 75 mg/m 2) for 8 cycles q21 days or EC>T (E 90 mg/m 2, C 600 mg/m2) for 4 cycles, followed by 4 cycles of a taxane q21 days. Choice of T (paclitaxel 175 mg/m2 or docetaxel 75 mg/m 2) was at the physician’s discretion. The primary endpoint is DFS. A 0.10 increase in the probability of DFS at 3 yrs for the ET arm would be considered clinically relevant. To detect 82 events, 300 subjects per arm are required to provide 90% power at 5% significance level. Results: 617 pts were enrolled from Nov 2000 to June 2003; 308 pts received ET and 309 pts received EC>T. Both treatment arms were well balanced with respect to age, nodal+, ER status, Her-2+ and PS; median age 52.5 (42%<50 years old); 70% ER+; 61% LN (1–3); 16% Her-2+; 87% PS 0. Total of 2206 cycles of treatment were given to ET compared 2314 cycles of treatment to EC>T. At 30 months of median follow-up there were DFS 102 events occurred; 47 events in ET arm (16%) and 55 events in EC>T arm (18%); 63 total deaths; 29 deaths in ET arm and 34 deaths in EC>T arm. The most common toxicities include alopecia (50%), fatigue (31%), nausea and vomiting (30%), dyspepsia (27%), febrile neutropenia (15%), constipation (12%), diarrhea (10%), arthralgia (11%), stomatitis (10%). In cardiac safety f/u, only one pt in ET arm remained LVEF drop >15. Conclusions: Epirubicin can be combined with taxanes in both sequential and concurrent therapies and both regimens are effective and well tolerated. The study is sponsored by Pfizer Inc.

No significant financial relationships to disclose.

Carboplatin, etoposide, and radiotherapy, followed by surgery, for the treatment of marginally resectable non-small cell lung cancer

The present study was undertaken in order to determine the feasibility and efficacy of induction chemotherapy with carboplatin and etoposide, followed by weekly carboplatin and full-course radiotherapy as pre-operative therapy for marginally resectable non-small cell lung cancer (NSCLC). Twenty-eight patients with good Eastern Cooperative Oncology Group (ECOG) performance status ratings and stage IIIA NSCLC received induction chemotherapy with carboplatin (dose computed with the Egorin formula, days 1 and 29) and etoposide (100 mg/m2/day, days 1 through 3 and 29 through 31). This was followed by 100 mg/m2 weekly carboplatin given over 6 weeks, concurrently with 60 Gy radiotherapy. Patients with either responsive or stable disease underwent thoracotomy 4 weeks after the completion of combined-modality therapy. All 28 patients received the first chemotherapy cycle (average carboplatin dose, 407 mg/m2; range, 195 to 586 mg/m2). World Health Organization (WHO) grade 3/4 neutropenia and thrombocytopenia were observed in 53 and 34% of patients, respectively. There were three febrile neutropenic episodes, but no septic deaths. Five patients (18%) required dose reductions prior to the second chemotherapy cycle, but the dose intensity of carboplatin was maintained (average dose, 390 mg/m2; range, 195 to 586 mg/m2). In all, 82% of patients received full-dose radiotherapy, and 73% received at least five of six planned concurrent weekly carboplatin doses. Carboplatin doses were most frequently delayed for thrombocytopenia and/or leukopenia. Carboplatin did not increase the incidence of radiation-induced esophagitis. Only three patients required interruption of radiotherapy, for esophagitis (two patients) and persistent thrombocytopenia (one patient). The response rate to pre-operative therapy was 64%. In this study, we demonstrated the ability to deliver escalated doses of carboplatin with standard-dose etoposide as induction chemotherapy with reasonable myelotoxicity. The combined-modality therapy was well tolerated, and the addition of weekly carboplatin did not result in increased radiation-related toxicity. This neoadjuvant regimen is active in the treatment of locally advanced NSCLC, and compares favorably to other cisplatin-based regimens.

Sensitive and specific detection of the 4B5 antigen in bronchial lavage specimens from patients with primary bronchogenic carcinoma

The monoclonal antibody 4B5 binds to a mucin-like antigen elaborated by respiratory epithelium of patients with non-small cell bronchogenic carcinoma. Several immunoassay formats were used to determine the presence of the antigen in lavage specimens. A qualitative immunodrop binding assay showed immunoreactivity in 37 (64%) of 58 specimens from patients with non-small cell lung cancer. In contrast, only 11 (12%) of 93 specimens from patients with either metastatic carcinoma or benign pulmonary diseases exhibited 4B5 immunoreactivity. A quantitative radioimmunoassay using standardized amounts of mucin exhibited similar sensitivity and specificity. Positive immunoreactivity was associated significantly with tobacco use and the cytopathologic diagnoses of squamous metaplasia, atypia, or dysplasia. Conversely, no significant association was found between 4B5 immunoreactivity and age, gender, race, benign cytologic findings, frankly malignant cytologic findings, or stage of disease. The expression of 4B5 antigen in bronchial secretions from patients with bronchogenic carcinoma deserves additional evaluation as a potential marker of pulmonary carcinogenesis.

Detection of a novel marker in the bronchial secretions of patients with non-small cell lung cancer using the 4B5 monoclonal antibody

A murine monoclonal antibody designated 4B5 was raised against the high molecular weight fraction of pooled sputum from patients with non-small cell lung cancer (NSCLC). Immunohistochemical staining indicated that 4B5 binds to histologically normal bronchial epithelium distant from tumor in 72% (39 of 54) of patients with NSCLC, but it binds to the primary cancer in only 13% (7 of 54) of the same patients. The antibody reacted less intensely with the bronchial epithelium in 16.6% (3 of 18) of autopsied patients without significant lung disease. The antigen recognized by 4B5 is a high molecular weight glycoprotein of more than 400 kilodaltons, judged by gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis and western blot analysis. Antigenic activity persisted after heating and resisted treatment with neuraminidase, but it was destroyed using protease and periodate. Multiple epitopes were present on each molecule recognized by 4B5. The determinants recognized by this antibody deserve additional study as possible markers of premalignant change in patients with NSCLC.