Extensive preclinical evaluation of lutetium-177-labeled PSMA-specific tracers for prostate cancer radionuclide therapy.

PURPOSE: Various radiolabeled prostate-specific membrane antigen (PSMA)-targeting tracers are clinically applied for prostate cancer (PCa) imaging and targeted radionuclide therapy. The PSMA binding affinities, biodistribution, and DNA-damaging capacities of these radiotracers have not yet been compared in detail. A major concern of PSMA-targeting radiotracers is the toxicity in other PSMA-expressing organs, such as the salivary glands, thus demanding careful evaluation of the most optimal and safest radiotracer. In this extensive preclinical study, we evaluated the clinically applied PSMA-targeting small molecule inhibitors DOTA-PSMA-617 (PSMA-617) and DOTAGA-PSMA-I&T (PSMA-I&T) and the PSMA nanobody DOTA-JVZ-007 (JVZ-007) using PSMA-expressing cell lines, a unique set of PCa patient-derived xenografts (PDX) and healthy human tissues. METHODS AND RESULTS: In vitro displacement studies on PSMA-expressing cells and cryosections of a PSMA-positive PDX revealed high and specific binding affinity for all three tracers labeled with lutetium-177 with IC50 values in the nanomolar range. Interestingly, [177Lu]Lu-JVZ-007 could not be displaced by PSMA-617 or PSMA-I&T, suggesting that this tracer targets an alternative binding site. Autoradiography assays on cryosections of human salivary and renal tissues revealed [177Lu]Lu-PSMA-617 to have the lowest binding to these healthy organs compared with [177Lu]Lu-PSMA-I&T. In vivo biodistribution assays confirmed the in vitro results with comparable tumor uptake of [177Lu]Lu-PSMA-617 and [177Lu]Lu-PSMA-I&T at all timepoints, resulting in induction of similar levels of DNA double-strand breaks in the tumors. However, [177Lu]Lu-PSMA-I&T demonstrated approximately 40× higher renal uptake at 4 and 8 h post injection resulting in an unfavorable tumor-to-kidney ratio. CONCLUSION: [177Lu]Lu-PSMA-617 has the most favorable biodistribution in mice as well as more favorable binding characteristics in vitro in PSMA-positive cells and human kidney and salivary gland specimens compared with [177Lu]Lu-PSMA-I&T and [177Lu]Lu-JVZ-007. Based on our preclinical evaluation, [177Lu]Lu-PSMA-617 is the best performing tracer to be taken further into clinical evaluation for PSMA-targeted radiotherapeutic development although with careful evaluation of the tracer binding to PSMA-expressing organs.

Computed Tomography and Magnetic Resonance Imaging.

Imaging in Oncology is rapidly moving from the detection and size measurement of a lesion to the quantitative assessment of metabolic processes and cellular and molecular interactions. Increasing insights into cancer as a complex disease with involvement of the tumor stroma in tumor pathobiological processes have made it clear that for successful control of cancer, treatment strategies should not only be directed at the cancer cells but should also take aspects of the tumor microenvironment into account. This requires an understanding of the complex molecular and cellular interactions in cancer tissue. Recent developments in imaging technology have increased the possibility to image various pathobiological processes in cancer development and response to treatment. For computed tomography (CT) and magnetic resonance imaging (MRI) various improvements in hardware, software, and imaging probes have lifted these modalities from classical anatomical imaging techniques to techniques suitable to image and quantify various physiological processes and molecular and cellular interactions. Next to a more general overview of possible imaging targets in oncology, this chapter provides an overview of the various developments in CT and MRI technology and some specific applications.

MSC encapsulation in alginate microcapsules prolongs survival after intra-articular injection, a longitudinal in vivo cell and bead integrity tracking study.

Mesenchymal stem cells (MSC) are promising candidates for use as a biological therapeutic. Since locally injected MSC disappear within a few weeks, we hypothesize that efficacy of MSC can be enhanced by prolonging their presence. Previously, encapsulation in alginate was suggested as a suitable approach for this purpose. We found no differences between the two alginate types, alginate high in mannuronic acid (High M) and alginate high in guluronic acid (High G), regarding MSC viability, MSC immunomodulatory capability, or retention of capsule integrity after subcutaneous implantation in immune competent rats. High G proved to be more suitable for production of injectable beads. Firefly luciferase-expressing rat MSC were used to track MSC viability. Encapsulation in high G alginate prolonged the presence of metabolically active allogenic MSC in immune competent rats with monoiodoacetate-induced osteoarthritis for at least 8 weeks. Encapsulation of human MSC for local treatment by intra-articular injection did not significantly influence the effect on pain, synovial inflammation, or cartilage damage in this disease model. MSC encapsulation in alginate allows for an injectable approach which prolongs the presence of viable cells subcutaneously or in an osteoarthritic joint. Further fine tuning of alginate formulation and effective dosage for might be required in order to improve therapeutic efficacy depending on the target disease. Graphical Abstract.

What is the best ST-segment recovery parameter to predict clinical outcome and myocardial infarct size? Amplitude, speed, and completeness of ST-segment recovery after primary percutaneous coronary intervention for ST-segment elevation myocardial infarction.

AIMS: ST-segment recovery (STR) is a strong mechanistic correlate of infarct size (IS) and outcome in ST-segment elevation myocardial infarction (STEMI). Characterizing measures of speed, amplitude, and completeness of STR may extend the use of this noninvasive biomarker. METHODS AND RESULTS: Core laboratory continuous 24-h 12-lead Holter ECG monitoring, IS by single-photon emission computed tomography (SPECT), and 30-day mortality of 2 clinical trials of primary percutaneous coronary intervention in STEMI were combined. Multiple ST measures (STR at last contrast injection (LC) measured from peak value; 30, 60, 90, 120, and 240min, residual deviation; time to steady ST recovery; and the 3-h area under the time trend curve [ST-AUC] from LC) were univariably correlated with IS and predictive of mortality. After multivariable adjustment for ST-parameters and GRACE risk factors, STR at 240min remained an additive predictor of mortality. Early STR, residual deviation, and ST-AUC remained associated with IS. CONCLUSIONS: Multiple parameters that quantify the speed, amplitude, and completeness of STR predict mortality and correlate with IS.

Ventricular arrhythmia burst is an independent indicator of larger infarct size even in optimal reperfusion in STEMI.

OBJECTIVE: We hypothesized that ventricular arrhythmia (VA) bursts during reperfusion phase are a marker of larger infarct size despite optimal epicardial and microvascular perfusion. METHODS: 126 STEMI patients were studied with 24h continuous, 12-lead Holter monitoring. Myocardial blush grade (MBG) was determined and VA bursts were identified against subject-specific background VA rates in core laboratories. Delayed-enhancement cardiovascular magnetic resonance imaging was used to determine infarct size. RESULTS: In the group with MBG 3 no significant differences were found for baseline characteristics between burst versus no burst (102 vs. 24). In those with optimal epicardial and microvascular reperfusion (TIMI 3, stable ST-recovery, and MBG 3), VA burst was associated with larger infarct size (N=102/126; median 11.0 vs. 5.1%; p=0.004). CONCLUSION: In the event of MBG 3, VA bursts were associated with significantly larger infarct size even if optimal epicardial and microvascular reperfusion was present.

The Balance Between the Therapeutic Efficacy and Safety of [177Lu]Lu-NeoB in a Preclinical Prostate Cancer Model.

PURPOSE: Radiolabeled NeoB is a promising gastrin-releasing peptide receptor (GRPR)-targeting radiopharmaceutical for theranostics of GRPR-expressing malignancies, e.g., prostate cancer (PCa). The aim of this study was to evaluate the effect of different doses of [177Lu]Lu-NeoB on the balance between therapeutic efficacy and safety in a preclinical PCa model. PROCEDURES: To determine the efficacy of [177Lu]Lu-NeoB, PC-3 xenografted mice received 3 sham injections (control group) or 3 injections of 30 MBq/300 pmol, 40 MBq/400 pmol, or 60 MBq/600 pmol [177Lu]Lu-NeoB (groups 1, 2, and 3, respectively) 1 week apart. To quantify tumor uptake, single-photon emission computed tomography/computed tomography (SPECT/CT) imaging was performed 4 h after the first, second, and third injection on a separate group of animals. For safety evaluations, pancreatic and renal tissues of non-tumor-bearing mice treated with the abovementioned [177Lu]Lu-NeoB doses were evaluated 12 and 24 weeks post-treatment. RESULTS: Treatment of PC-3 tumors with all three studied [177Lu]Lu-NeoB doses was effective. Median survival times were significantly (p < 0.0001) improved for treatment groups 1, 2, and 3 versus the control group (82 days, 89 days, 99 days versus 19 days, respectively). However, no significant differences were observed between treatment groups. Quantification of SPECT/CT images showed minimal differences in the average absolute radioactivity uptake, especially after the third injection. Histopathological analysis revealed no clear signs of treatment-related pancreatic toxicity. For the kidneys, atrophy and fibrosis were observed for one animal from group 1 and a chronic inflammatory response was observed for both animals from group 3 at 24 weeks post-treatment. CONCLUSIONS: Treatment with [177Lu]Lu-NeoB is effective in a preclinical PCa model. Adjusting the administered dose could positively impact the risk-benefit balance as a higher dose might not lead to an increased therapeutic effect, but it may lead to an increase in toxicological effects in healthy organs such as the kidneys.

Computed tomography and magnetic resonance imaging.

Imaging in Oncology is rapidly moving from the detection and size measurement of a lesion to the quantitative assessment of metabolic processes and cellular and molecular interactions. Increasing insights into cancer as a complex disease with involvement of the tumor stroma in tumor pathobiological processes have made it clear that for successful control of cancer, treatment strategies should not only be directed at the tumor cells but also targeted at the tumor microenvironment. This requires understanding of the complex molecular and cellular interactions in cancer tissue. Recent developments in imaging technology have increased the possibility to image various pathobiological processes in cancer development and response to treatment. For computed tomography (CT) and magnetic resonance imaging (MRI) various improvements in hardware, software, and imaging probes have lifted these modalities from classical anatomical imaging techniques to techniques suitable to image and quantify various physiological processes and molecular and cellular interactions. Next to a more general overview of possible imaging targets in oncology this chapter provides an overview of the various developments in CT and MRI technology and some specific applications.

Multiple biomarkers at admission are associated with angiographic, electrocardiographic, and imaging cardiovascular mechanistic markers of outcomes in patients undergoing primary percutaneous coronary intervention for acute ST-elevation myocardial infarction.

BACKGROUND: The multimarker risk score, based on estimated glomerular filtration rate, glucose, and N-terminal probrain natriuretic peptide (NT-proBNP), has been shown to predict mortality in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). In this study, we investigated the relation between the multimarker risk score and cardiovascular mechanistic markers of outcomes in STEMI patients undergoing PPCI. METHODS: Complete biomarkers were available in 197 patients with STEMI. Angiographic Thrombolysis In Myocardial Infarction flow grade and myocardial blush grade at the end of the PPCI, electrocardiographic ST-segment resolution (STR) at the time of last contrast injection and 240 minutes after last contrast, and cardiac magnetic resonance (CMR) left ventricular ejection fraction (LVEF) and infarct size at 4 to 6 months after the index event were available. RESULTS: In linear regression models, higher multimarker scores were associated with worse angiographic (P < .01 for both outcomes), electrocardiographic (P < .001 for the association with STR at last contrast, and P < .01 for STR at 240 minutes), and CMR outcomes (P < .01 for both). CONCLUSIONS: The multimarker risk score is associated with angiographic, electrocardiographic, and CMR mechanistic markers of outcomes. These data support the ability of the multimarker risk score to identify patients at high risk for suboptimal reperfusion and CMR outcomes and may aid in the early triage of patients who stand to benefit most of adjuvant treatments in STEMI.

Towards Complete Tumor Resection: Novel Dual-Modality Probes for Improved Image-Guided Surgery of GRPR-Expressing Prostate Cancer.

Nuclear and optical dual-modality probes can be of great assistance in prostate cancer localization, providing the means for both preoperative nuclear imaging and intraoperative surgical guidance. We developed a series of probes based on the backbone of the established GRPR-targeting radiotracer NeoB. The inverse electron demand of the Diels-Alder reaction was used to integrate the sulfo-cyanine 5 dye. Indium-111 radiolabeling, stability studies and a competition binding assay were carried out. Pilot biodistribution and imaging studies were performed in PC-3 tumor-bearing mice, using the best two dual-labeled probes. The dual-modality probes were radiolabeled with a high yield (>92%), were proven to be hydrophilic and demonstrated high stability in mouse serum (>94% intact labeled ligand at 4 h). The binding affinity for the GRPR was in the nanomolar range (21.9-118.7 nM). SPECT/CT images at 2 h p.i. clearly visualized the tumor xenograft and biodistribution studies, after scanning confirmed the high tumor uptake (8.47 ± 0.46%ID/g and 6.90 ± 0.81%ID/g for probe [111In]In-12 and [111In]In-15, respectively). Receptor specificity was illustrated with blocking studies, and co-localization of the radioactive and fluorescent signal was verified by ex vivo fluorescent imaging. Although optimal tumor-to-blood and tumor-to-kidney ratios might not yet have been reached due to the prolonged blood circulation, our probes are promising candidates for the preoperative and intraoperative visualization of GRPR-positive prostate cancer.

Computer-assisted quantification of myocardial reperfusion after primary percutaneous coronary intervention predicts functional and contrast-enhanced cardiovascular magnetic resonance outcomes in patients with ST-segment elevation myocardial infarction.

OBJECTIVE: We investigated whether the Quantitative Blush Evaluator (QuBE) value predicts functional and contrast-enhanced cardiovascular magnetic resonance (CMR) outcomes at 4-6 months after primary percutaneous coronary intervention (PCI) inpatients with ST-segment elevation myocardial infarction (STEMI). BACKGROUND: QuBEis a computer-assisted open source program to quantify myocardial reperfusion.Although a higher QuBE value is associated with improved myocardial reperfusion measures and lower 1-year mortality, the association with intermediate functional parameters after STEMI has not yet been investigated. METHODS: QuBE values were quantified retrospectively on angiograms of patients enrolled in the ancillary CMR study of the proximal embolic protection in acute myocardial infarction and resolution of ST-elevation trial. QuBE en CMR outcomes were independently assessed by reviewers blinded to clinical data. RESULTS: A higher QuBE value was significantly associated with a smaller left ventricular (LV) end-diastolic and end-systolic volume, a higher LV ejection fraction and systolic wall thickening in the infarct area, and a smaller final infarct size and extent of transmural segments (P ≤ 0.008). In a multivariable model, including age, gender, infarct location, time to treatment, history of myocardial infarction, and postprocedural thrombolysis in myocardial infarction flow grade,only the QuBE value and infarct location remained as independent predictors of LV ejection fraction (P 5 0.018 for QuBE value). CONCLUSION: Higher QuBE values are independently associated with improved functional and contrast-enhanced CMR outcomes including LV ejection fraction at 4-6 months after primary PCI and may therefore aid in identifying high-risk patients who benefit most from adjunctive therapies sustaining myocardial function after PCI.

Impact of early, late, and no ST-segment resolution measured by continuous ST Holter monitoring on left ventricular ejection fraction and infarct size as determined by cardiovascular magnetic resonance imaging.

BACKGROUND: The goal of this study is to determine the predictive value of ST-segment resolution (STR) early after percutaneous coronary intervention (PCI), late STR, and no STR for left ventricular ejection fraction (LVEF) and infarct size (IS) by cardiovascular magnetic resonance (CMR) at follow-up in patients with ST-segment elevation myocardial infarction. METHODS: The analysis included 199 patients who were enrolled in the PRoximal Embolic Protection in Acute myocardial infarction and Resolution of ST-Elevation trial and in whom both continuous ST Holter and CMR at follow-up were available. Patients were stratified into 3 groups: (1) early complete (≥70%) STR measured immediately after last contrast injection (n = 113); (2) late complete STR (n = 52), defined as complete STR from 30 to 240 minutes after PCI; and (3) no complete STR after 240 minutes (n = 34). RESULTS: Patients with early STR had more preserved LVEF and smaller IS compared to patients with late STR or no STR (LVEF: early STR, 54% ± 8%; late STR, 46% ± 13%; no STR, 43% ± 11%; and IS: 3.9 ± 3.3 g/m(2); 8.0 ± 6.9 g/m(2); 12.0 ± 6.0 g/m(2); respectively; all P < .0001). Early STR was independently predictive for LVEF (ß = 8.5; P = .0005) and IS (ß = -7.0; P < .0001). Late STR was not predictive for LVEF (ß = 1.6; P = .51) but predictive for IS (ß = -3.5; P = .003). CONCLUSIONS: Patients with early complete STR after primary PCI have better preserved LVEF and smaller IS. Patients with late complete STR do not have better preserved LVEF but do have smaller IS. ST-segment resolution is a strong, independent predictor of LVEF and IS as assessed by CMR.

Theranostic Design of Angiopep-2 Conjugated Hyaluronic Acid Nanoparticles (Thera-ANG-cHANPs) for Dual Targeting and Boosted Imaging of Glioma Cells.

Glioblastoma multiforme (GBM) has a mean survival of only 15 months. Tumour heterogeneity and blood-brain barrier (BBB) mainly hinder the transport of active agents, leading to late diagnosis, ineffective therapy and inaccurate follow-up. The use of hydrogel nanoparticles, particularly hyaluronic acid as naturally occurring polymer of the extracellular matrix (ECM), has great potential in improving the transport of drug molecules and, furthermore, in facilitatating the early diagnosis by the effect of hydrodenticity enabling the T1 boosting of Gadolinium chelates for MRI. Here, crosslinked hyaluronic acid nanoparticles encapsulating gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) and the chemotherapeutic agent irinotecan (Thera-cHANPs) are proposed as theranostic nanovectors, with improved MRI capacities. Irinotecan was selected since currently repurposed as an alternative compound to the poorly effective temozolomide (TMZ), generally approved as the gold standard in GBM clinical care. Also, active crossing and targeting are achieved by theranostic cHANPs decorated with angiopep-2 (Thera-ANG-cHANPs), a dual-targeting peptide interacting with low density lipoprotein receptor related protein-1(LRP-1) receptors overexpressed by both endothelial cells of the BBB and glioma cells. Results showed preserving the hydrodenticity effect in the advanced formulation and internalization by the active peptide-mediated uptake of Thera-cHANPs in U87 and GS-102 cells. Moreover, Thera-ANG-cHANPs proved to reduce ironotecan time response, showing a significant cytotoxic effect in 24 h instead of 48 h.

Fluorinated PLGA-PEG-Mannose Nanoparticles for Tumor-Associated Macrophage Detection by Optical Imaging and MRI.

Tumor-associated macrophages (TAMs) promote cancer growth and metastasis, but their role in tumor development needs to be fully understood due to the dynamic changes of tumor microenvironment (TME). Here, we report an approach to visualize TAMs by optical imaging and by Fluorine-19 (19F) magnetic resonance imaging (MRI) that is largely applied to track immune cells in vivo. TAMs are targeted with PLGA-PEG-mannose nanoparticles (NPs) encapsulating perfluoro-15-crown-5-ether (PFCE) as MRI contrast agent. These particles are preferentially recognized and phagocytized by TAMs that overexpress the mannose receptor (MRC1/CD206). The PLGA-PEG-mannose NPs are not toxic and they were up-taken by macrophages as confirmed by in vitro confocal microscopy. At 48 h after intravenous injection of PLGA-PEG-mannose NPs, 4T1 xenograft mice were imaged and fluorine-19 nuclear magnetic resonance confirmed nanoparticle retention at the tumor site. Because of the lack of 19F background in the body, observed 19F signals are robust and exhibit an excellent degree of specificity. In vivo imaging of TAMs in the TME by 19F MRI opens the possibility for detection of cancer at earlier stage and for prompt therapeutic interventions in solid tumors.

Inter and intra-tumor somatostatin receptor 2 heterogeneity influences peptide receptor radionuclide therapy response.

Patients with neuroendocrine tumors (NETs) can be treated with peptide receptor radionuclide therapy (PRRT). Here, the somatostatin analogue octreotate radiolabeled with lutetium-177 is targeted to NET cells by binding to the somatostatin receptor subtype 2 (SST2). During radioactive decay, DNA damage is induced, leading to NET cell death. Although the therapy proves to be effective, mortality rates remain high. To appropriately select more optimal treatment strategies, it is essential to first better understand the radiobiological responses of tumor cells to PRRT. Methods: We analyzed PRRT induced radiobiological responses in SST2 expressing cells and xenografted mice using SPECT/MRI scanning and histological and molecular analyses. We measured [177Lu]Lu-DOTA-TATE uptake and performed analyses to visualize induction of DNA damage, cell death and other cellular characteristics. Results: The highest accumulation of radioactivity was measured in the tumor and kidneys. PRRT induced DNA damage signaling and repair in a time-dependent manner. We observed intra-tumor heterogeneity of DNA damage and apoptosis, which was not attributed to proliferation or bioavailability. We found a strong correlation between high DNA damage levels and high SST2 expression. PRRT elicited a different therapeutic response between models with different SST2 expression levels. Heterogeneous SST2 expression levels were also confirmed in patient NETs. Conclusion: Heterogeneous SST2 expression levels within NETs cause differentially induced DNA damage levels, influence recurrent tumor phenotypes and impact the therapeutic response in different models and potentially in patients. Our results contribute to a better understanding of PRRT effects, which might impact future therapeutic outcome of NET patients.

In Vivo Evaluation of Gallium-68-Labeled IRDye800CW as a Necrosis Avid Contrast Agent in Solid Tumors.

Necrosis only occurs in pathological situations and is directly related to disease severity and, therefore, is an important biomarker. Tumor necrosis occurs in most solid tumors due to improperly functioning blood vessels that cannot keep up with the rapid growth, especially in aggressively growing tumors. The amount of necrosis per tumor volume is often correlated to rapid tumor proliferation and can be used as a diagnostic tool. Furthermore, efficient therapy against solid tumors will directly or indirectly lead to necrotic tumor cells, and detection of increased tumor necrosis can be an early marker for therapy efficacy. We propose the application of necrosis avid contrast agents to detect therapy-induced tumor necrosis. Herein, we advance gallium-68-labeled IRDye800CW, a near-infrared fluorescent dye that exhibits excellent necrosis avidity, as a potential PET tracer for in vivo imaging of tumor necrosis. We developed a reliable labeling procedure to prepare [68Ga]Ga-DOTA-PEG4-IRDye800CW ([68Ga]Ga-1) with a radiochemical purity of >96% (radio-HPLC). The prominent dead cell binding of fluorescence and radioactivity from [68Ga]Ga-1 was confirmed with dead and alive cultured 4T1-Luc2 cells. [68Ga]Ga-1 was injected in 4T1-Luc2 tumor-bearing mice, and specific fluorescence and PET signal were observed in the spontaneously developing tumor necrosis. The ip injection of D-luciferin enabled simultaneous bioluminescence imaging of the viable tumor regions. Tumor necrosis binding was confirmed ex vivo by colocalization of fluorescence uptake with TUNEL dead cell staining and radioactivity uptake in dichotomized tumors and frozen tumor sections. Our presented study shows that [68Ga]Ga-1 is a promising PET tracer for the detection of tumor necrosis.

Does the proteasome inhibitor bortezomib sensitize to DNA-damaging therapy in gastroenteropancreatic neuroendocrine neoplasms? - A preclinical assessment in vitro and in vivo.

BACKGROUND: Well-differentiated gastroenteropancreatic neuroendocrine neoplasms are rare tumors with a slow proliferation. They are virtually resistant to many DNA-damaging therapeutic approaches, such as chemo- and external beam therapy, which might be overcome by DNA damage inhibition induced by proteasome inhibitors such as bortezomib. METHODS AND RESULTS: In this study, we assessed several combined treatment modalities in vitro and in vivo. By cell-based functional analyses, in a 3D in ovo and an orthotopic mouse model, we demonstrated sensitizing effects of bortezomib combined with cisplatin, radiation and peptide receptor radionuclide therapy (PRRT). By gene expression profiling and western blot, we explored the underlying mechanisms, which resulted in an impaired DNA damage repair. Therapy-induced DNA damage triggered extrinsic proapoptotic signaling as well as the induction of cell cycle arrest, leading to a decreased vital tumor volume and altered tissue composition shown by magnetic resonance imaging and F-18-FDG-PET in vivo, however with no significant additional benefit related to PRRT alone. CONCLUSIONS: We demonstrated that bortezomib has short-term sensitizing effects when combined with DNA damaging therapy by interfering with DNA repair in vitro and in ovo. Nevertheless, due to high tumor heterogeneity after PRRT in long-term observations, we were not able to prove a therapeutic advantage of bortezomib-combined PRRT in an in vivo mouse model.

Percutaneous Coronary Intervention vs Medical Therapy for Coronary Lesions With Positive Fractional Flow Reserve (FFR) but Preserved Pressure-Bounded Coronary Flow Reserve (CFR): A Substudy of the Randomized Compare-Acute Trial.

OBJECTIVES: Performing percutaneous coronary intervention (PCI) for fractional flow reserve (FFR) positive coronary lesions improves clinical outcomes and is recommended by international guidelines. It has been hypothesized that lesions with a positive FFR but a preserved coronary flow reserve (CFR) are less likely to be flow limiting and might best be treated medically. We investigated the association of CFR in FFR-positive lesions with clinical outcomes when treated medically, as well as the treatment effect of PCI vs medical therapy in FFR-positive lesions and a preserved CFR. METHODS: We performed a substudy of the randomized, multicenter Compare-Acute trial, in which stabilized ST-segment elevation myocardial infarction (STEMI) patients with non-culprit lesions were randomized to either FFR-guided PCI or medical therapy. Based on baseline and hyperemic pressure gradients, we computed physiologic limits of CFR, the so-called pressure-bounded CFR (pb-CFR), and classified lesions as low (<2) or preserved (≥2). The primary endpoint was 12-month major adverse cardiac and cerebrovascular event (MACCE) rate, defined as a composite of death from any cause, non-fatal myocardial infarction, revascularization, or cerebrovascular events. RESULTS: A total of 980 lesions from 885 patients were included in this substudy. In lesions with FFR ≤0.80, a total of 249 patients had a pb-CFR <2 and 29 patients had a preserved CFR (pb-CFR ≥2). The rate of MACCE at 1 year was not significantly different between patients with FFR ≤0.80 and pb-CFR <2 vs patients with FFR ≤0.80 and pb-CFR ≥2 (25% vs 17%, respectively; P=.39). Because of randomization, baseline characteristics were well balanced between patients with FFR ≤0.80 and pb-CFR ≥2 treated by either by PCI or medical therapy. Importantly, in patients with FFR ≤0.80 and pb-CFR ≥2, MACCE occurred more frequently in patients treated medically vs patients treated by PCI (44% vs 0%, respectively; P=.01). CONCLUSIONS: Preserved or low pb-CFR did not alter clinical outcomes in patients with a positive FFR. Patients with FFR-positive coronary lesions but a preserved CFR had more clinical events when treated medically vs those treated with PCI.

Early ST-segment recovery after primary percutaneous coronary intervention accurately predicts long-term prognosis after acute myocardial infarction.

BACKGROUND: Several ancillary studies reported on the prognostic value of ST-segment recovery (STR) with measurement at 30 to 240 minutes after primary percutaneous coronary intervention (PCI). We determined the long-term prognostic value of early STR, assessed at the end of primary PCI, in unselected patients after ST-segment elevation myocardial infarction (STEMI). METHODS: We analyzed 12-lead electrocardiograms, recorded in the catheterization laboratory before arterial puncture and at the time of the end of PCI, from 2,124 STEMI patients who underwent primary PCI at our institution between 2000 and 2007. ST-segment recovery was categorized as complete (> or =70%), partial (30%-70%), or absent (<30%). Median follow-up was 4.1 years. RESULTS: The estimated 5-year mortality was 8.3% in patients with complete STR, 14.4% in patients with partial STR, and 22.8% in patients with absent STR (P < .001). Multivariable-adjusted hazard ratios for 1-year death of patients with partial and absent STR, as compared with patients with complete STR, were 2.1 (95% CI 1.2-3.8, P = .014) and 3.2 (95% CI 1.8-5.8, P < .001), respectively. In a landmark analysis restricted to 1-year survivors, early STR was significantly predictive of 5-year mortality, even after multivariable adjustment. CONCLUSIONS: Early STR assessment has strong, long-term prognostic properties in all-comer STEMI patients. Moreover, the prognostic power of early STR is not restricted to the early recovery phase after STEMI, but identifies high-risk subgroups among 1-year survivors.

Feasibility and applicability of computer-assisted myocardial blush quantification after primary percutaneous coronary intervention for ST-segment elevation myocardial infarction.

OBJECTIVES: The aim of the study was to evaluate whether the "Quantitative Blush Evaluator" (QuBE) score is associated with measures of myocardial reperfusion in patients with ST-segment elevation myocardial infarction (STEMI) treated in two hospitals with 24/7 coronary intervention facilities. BACKGROUND: QuBE is an open source computer program to quantify myocardial perfusion. Although QuBE has shown to be practical and feasible in the patients enrolled in the Thrombus Aspiration during Percutaneous Coronary Intervention in Acute Myocardial Infarction Study (TAPAS), QuBE has not yet been verified on reperfusion outcomes of primary percutaneous coronary intervention (PCI) patients treated in other catheterization laboratories. METHODS: Core lab adjudicated angiographic outcomes and QuBE values were assessed on angiograms of patients who were enrolled in the PRoximal Embolic Protection in Acute myocardial infarction and Resolution of ST-Elevation (PREPARE) trial. ST-segment resolution immediately after PCI measured by continuous ST Holter monitoring was calculated by a blinded core lab. RESULTS: The QuBE score could be assessed on 229 of the 284 angiograms (81%) and was significantly associated with visually assessed myocardial blush grade (P < 0.0001). Patients with improved postprocedural Thrombolysis in Myocardial Infarction-graded flow, myocardial blush grade, ST-segment resolution immediately after PCI, or a small infarct size measured by peak CK-MB had a significant better QuBE score. CONCLUSIONS: QuBE is feasible and applicable at angiograms of patients with STEMI recorded at other catheterization laboratories and is associated with measures of myocardial reperfusion.

ST-segment resolution prior to primary percutaneous coronary intervention is a poor indicator of coronary artery patency in patients with acute myocardial infarction.

BACKGROUND: The prognostic value of ST-segment resolution (STR) after initiation of reperfusion therapy has been established by various studies conducted in both the thrombolytic and mechanic reperfusion era. However, data regarding the value of STR immediately prior to primary percutaneous coronary intervention (PCI) to predict infarct-related artery (IRA) patency remain limited. We investigated whether STR prior to primary PCI is a reliable, noninvasive indicator of IRA patency in patients with ST-segment elevation myocardial infarction (STEMI). METHODS: The study population consisted of STEMI patients who underwent primary PCI at our institution between 2000 and 2007. STR was analyzed in 12-lead electrocardiograms recorded at first medical contact and immediately prior to primary PCI and defined as complete (> or =70%), partial (70%- 30%), or absent (<30%). RESULTS: In 1253 patients with a complete data set, STR was inversely related to the probability of impaired preprocedural flow (P(for trend) < 0.001). Although the sensitivity of incomplete (<70%) STR to predict a Thrombolysis in Myocardial Infarction (TIMI) flow of <3 was 96%, the specificity was 23%, and the negative predictive value of incomplete STR to predict normal coronary flow was only 44%. CONCLUSIONS: This study establishes the correlation between STR prior to primary PCI and preprocedural TIMI flow in STEMI patients treated with primary PCI. However, the negative predictive value of incomplete STR for detection of TIMI-3 flow is only 44% and therefore should not be a criterion to refrain from immediate coronary angiography in STEMI patients.