Evaluation of a portable retinal imaging device: towards a comparative quantitative analysis for morphological measurements of retinal blood vessels.

This study investigated the possibility of using low-cost, handheld, retinal imaging devices for the automatic extraction of quantifiable measures of retinal blood vessels. Initially, the available handheld devices were compared using a Zeiss model eye incorporating a USAF resolution test chart to assess their optical properties. The only suitable camera of the five evaluated was the Horus DEC 200. This device was then subjected to a detailed evaluation in which images in human eyes taken from the handheld camera were compared in a quantitative analysis with those of the same eye from a Canon CR-DGi retinal desktop camera. We found that the Horus DEC 200 exhibited shortcomings in capturing images of human eyes by comparison with the Canon. More images were rejected as being unevaluable or suffering failures in automatic segmentation than with the Canon, and even after exclusion of affected images, the Horus yielded lower measurements of vessel density than the Canon. A number of issues affecting handheld cameras in general and some features of the Horus in particular have been identified that might contribute to the observed differences in performance. Some potential mitigations are discussed which might yield improvements in performance, thus potentially facilitating use of handheld retinal imaging devices for quantitative retinal microvascular measurements.

Cardiopulmonary exercise testing and efficacy of percutaneous coronary intervention: a substudy of the ORBITA trial.

AIMS: Oxygen-pulse morphology and gas exchange analysis measured during cardiopulmonary exercise testing (CPET) has been associated with myocardial ischaemia. The aim of this analysis was to examine the relationship between CPET parameters, myocardial ischaemia and anginal symptoms in patients with chronic coronary syndrome and to determine the ability of these parameters to predict the placebo-controlled response to percutaneous coronary intervention (PCI). METHODS AND RESULTS: Patients with severe single-vessel coronary artery disease (CAD) were randomized 1:1 to PCI or placebo in the ORBITA trial. Subjects underwent pre-randomization treadmill CPET, dobutamine stress echocardiography (DSE) and symptom assessment. These assessments were repeated at the end of a 6-week blinded follow-up period.A total of 195 patients with CPET data were randomized (102 PCI, 93 placebo). Patients in whom an oxygen-pulse plateau was observed during CPET had higher (more ischaemic) DSE score [+0.82 segments; 95% confidence interval (CI): 0.40 to 1.25, P = 0.0068] and lower fractional flow reserve (-0.07; 95% CI: -0.12 to -0.02, P = 0.011) compared with those without. At lower (more abnormal) oxygen-pulse slopes, there was a larger improvement of the placebo-controlled effect of PCI on DSE score [oxygen-pulse plateau presence (Pinteraction = 0.026) and oxygen-pulse gradient (Pinteraction = 0.023)] and Seattle angina physical-limitation score [oxygen-pulse plateau presence (Pinteraction = 0.037)]. Impaired peak VO2, VE/VCO2 slope, peak oxygen-pulse, and oxygen uptake efficacy slope was significantly associated with higher symptom burden but did not relate to severity of ischaemia or predict response to PCI. CONCLUSION: Although selected CPET parameters relate to severity of angina symptoms and quality of life, only an oxygen-pulse plateau detects the severity of myocardial ischaemia and predicts the placebo-controlled efficacy of PCI in patients with single-vessel CAD.

Association of Low-Dose Triple Combination Therapy vs Usual Care With Time at Target Blood Pressure: A Secondary Analysis of the TRIUMPH Randomized Clinical Trial.

Importance: Cumulative exposure to high blood pressure (BP) is an adverse prognostic marker. Assessments of BP control over time, such as time at target, have been developed but assessments of the effects of BP-lowering interventions on such measures are lacking. Objective: To evaluate whether low-dose triple combination antihypertensive therapy was associated with greater rates of time at target compared with usual care. Design, Setting, and Participants: The Triple Pill vs Usual Care Management for Patients With Mild-to-Moderate Hypertension (TRIUMPH) trial was a open-label randomized clinical trial of low-dose triple BP therapy vs usual care conducted in urban hospital clinics in Sri Lanka from February 2016 to May 2017. Adults with hypertension (systolic BP >140 mm Hg and/or diastolic BP >90 mm Hg or in patients with diabetes or chronic kidney disease, systolic BP >130 mm Hg and/or diastolic BP >80 mm Hg) requiring initiation (untreated patients) or escalation (patients receiving monotherapy) of antihypertensive therapy were included. Patients were excluded if they were currently taking 2 or more blood pressure-lowering drugs or had severe or uncontrolled blood pressure, accelerated hypertension or physician-determined need for slower titration of treatment, a contraindication to the triple combination pill therapy, an unstable medical condition, or clinically significant laboratory values deemed by researchers to be unsuitable for the study. All 700 individuals in the original trial were included in the secondary analysis. This post hoc analysis was conducted from December 2020 to December 2021. Intervention: Once-daily fixed-dose triple combination pill (telmisartan 20 mg, amlodipine 2.5 mg, and chlorthalidone 12.5 mg) therapy vs usual care. Main Outcomes and Measures: Between-group differences in time at target were compared over 24 weeks of follow-up, with time at target defined as percentage of time at target BP. Results: There were a total of 700 randomized patients (mean [SD] age, 56 [11] years; 403 [57.6%] women). Patients allocated to the triple pill group (n = 349) had higher time at target compared with those in the usual care group (n = 351) over 24 weeks' follow-up (64% vs 43%; risk difference, 21%; 95% CI, 16-26; P < .001). Almost twice as many patients receiving triple pill therapy achieved more than 50% time at target during follow-up (64% vs 37%; P < .001). The association of the triple pill with an increase in time at target was seen early, with most patients achieving more than 50% time at target by 12 weeks. Those receiving the triple pill achieved a consistently higher time at target at all follow-up periods compared with those receiving usual care (mean [SD]: 0-6 weeks, 36.3% [30.9%] vs 21.7% [28.9%]; P < .001; 6-12 weeks, 55.2% [31.9%] vs 33.7% [33.0%]; P < .001; 12-24 weeks, 66.0% [31.1%] vs 43.5% [34.3%]; P < .001). Conclusions and Relevance: To our knowledge, this analysis provides the first estimate of time at target as an outcome assessing longitudinal BP control in a randomized clinical trial. Among patients with mild to moderate hypertension, treatment with a low-dose triple combination pill was associated with substantially higher time at target compared with usual care.

Multiphysics Modelling and Simulation of Thrombolysis via Activated Platelet-Targeted Nanomedicine.

PURPOSE: This study establishes a multiphysics simulation platform for both conventional and targeted thrombolysis using tissue plasminogen activator (tPA). Based on our computational results, the effects of therapeutic parameters on the dynamics of thrombolysis and the risk of side effects are investigated. METHODS: The model extends our previously developed one-dimensional(1D) mathematical models for fibrinolysis by incorporating targeted thrombolysis. It consists of two parts: (i) a coupled mathematical model of systemic pharmacokinetics (PK) and pharmacodynamics (PD) and local PD in a 1D occluded artery, and (ii) a mechanistic model for a targeted thrombolytic system via activated platelet-targeted tPA-loaded nanovesicles (tPA-NV), with model parameters derived from our in vitro experiments. A total of 16 therapeutic scenarios are simulated by varying the clot location and composition as well as the dosing regimen with free tPA or tPA-NV. RESULTS: Our simulation results indicate that tPA-NV offers several advantages over free tPA for thrombolysis. It reduces systemic exposure of tPA, thereby minimising the risk of bleeding complications. Simulations with different tPA-NV doses reveal that tPA-NV at 10% of the recommended dose can be as effective as the standard regimen with the full recommended dose of free tPA, demonstrating the potential of our tPA-NV as a new thrombolytic strategy with a reduced tPA dose. Moreover, faster recanalisation can be achieved with tPA-NV, especially for platelet-rich(or fibrin-poor) clots. CONCLUSIONS: Our simulation platform for thrombolysis with well-tuned model parameters can be used to evaluate and optimise treatment regimens of existing and new thrombolytic therapies via benefit/risk assessment under various therapeutic scenarios.

Side Effect Patterns in a Crossover Trial of Statin, Placebo, and No Treatment.

BACKGROUND: Most people who begin statins abandon them, most commonly because of side effects. OBJECTIVES: The purpose of this study was to assess daily symptom scores on statin, placebo, and no treatment in participants who had abandoned statins. METHODS: Participants received 12 1-month medication bottles, 4 containing atorvastatin 20 mg, 4 placebo, and 4 empty. We measured daily symptom intensity for each using an app (scale 1-100). We also measured the "nocebo" ratio: the ratio of symptoms induced by taking statin that was also induced by taking placebo. RESULTS: A total of 60 participants were randomized and 49 completed the 12-month protocol. Mean symptom score was 8.0 (95% CI: 4.7-11.3) in no-tablet months. It was higher in statin months (16.3; 95% CI: 13.0-19.6; P < 0.001), but also in placebo months (15.4; 95% CI: 12.1-18.7; P < 0.001), with no difference between the 2 (P = 0.388). The corresponding nocebo ratio was 0.90. In the individual-patient daily data, neither symptom intensity on starting (OR: 1.02; 95% CI: 0.98-1.06; P = 0.28) nor extent of symptom relief on stopping (OR: 1.01; 95% CI: 0.98-1.05; P = 0.48) distinguished between statin and placebo. Stopping was no more frequent for statin than placebo (P = 0.173), and subsequent symptom relief was similar between statin and placebo. At 6 months after the trial, 30 of 60 (50%) participants were back taking statins. CONCLUSIONS: The majority of symptoms caused by statin tablets were nocebo. Clinicians should not interpret symptom intensity or timing of symptom onset or offset (on starting or stopping statin tablets) as indicating pharmacological causation, because the pattern is identical for placebo. (Self-Assessment Method for Statin Side-effects Or Nocebo [SAMSON]; NCT02668016).

Fibrinogen-mimicking, multiarm nanovesicles for human thrombus-specific delivery of tissue plasminogen activator and targeted thrombolytic therapy.

Clinical use of tissue plasminogen activator (tPA) in thrombolytic therapy is limited by its short circulation time and hemorrhagic side effects. Inspired by fibrinogen binding to activated platelets, we report a fibrinogen-mimicking, multiarm nanovesicle for thrombus-specific tPA delivery and targeted thrombolysis. This biomimetic system is based on the lipid nanovesicle coated with polyethylene glycol (PEG) terminally conjugated with a cyclic RGD (cRGD) peptide. Our experiments with human blood demonstrated its highly selective binding to activated platelets and efficient tPA release at a thrombus site under both static and physiological flow conditions. Its clot dissolution time in a microfluidic system was comparable to that of free tPA. Furthermore, we report a purpose-built computational model capable of simulating targeted thrombolysis of the tPA-loaded nanovesicle and with a potential in predicting the dynamics of thrombolysis in physiologically realistic scenarios. This combined experimental and computational work presents a promising platform for development of thrombolytic nanomedicines.

Achieving optimal adherence to medical therapy by telehealth: Findings from the ORBITA medication adherence sub-study.

INTRODUCTION: The ORBITA trial of percutaneous coronary intervention (PCI) versus a placebo procedure for patients with stable angina was conducted across six sites in the United Kingdom via home monitoring and telephone consultations. Patients underwent detailed assessment of medication adherence which allowed us to measure the efficacy of the implementation of the optimization protocol and interpretation of the main trial endpoints. METHODS: Prescribing data were collected throughout the trial. Self-reported adherence was assessed, and urine samples collected at pre-randomization and at follow-up for direct assessment of adherence using high-performance liquid chromatography with tandem mass spectrometry (HPLC MS/MS). RESULTS: Self-reported adherence was >96% for all drugs in both treatment groups at both stages. The percentage of samples in which drug was detected at pre-randomization and at follow-up in the PCI versus placebo groups respectively was: clopidogrel, 96% versus 90% and 98% versus 94%; atorvastatin, 95% versus 92% and 92% versus 91%; perindopril, 95% versus 97% and 85% versus 100%; bisoprolol, 98% versus 99% and 96% versus 97%; amlodipine, 99% versus 99% and 94% versus 96%; nicorandil, 98% versus 96% and 94% versus 92%; ivabradine, 100% versus 100% and 100% versus 100%; and ranolazine, 100% versus 100% and 100% versus 100%. CONCLUSIONS: Adherence levels were high throughout the study when quantified by self-reporting methods and similarly high proportions of drug were detected by urinary assay. The results indicate successful implementation of the optimization protocol delivered by telephone, an approach that could serve as a model for treatment of chronic conditions, particularly as consultations are increasingly conducted online.

Omega-3 index and blood pressure responses to eating foods naturally enriched with omega-3 polyunsaturated fatty acids: a randomized controlled trial.

Diets low in seafood omega-3 polyunsaturated fatty acids (PUFAs) are very prevalent. Such diets have recently been ranked as the sixth most important dietary risk factor-1.5 million deaths and 33 million disability-adjusted life-years worldwide are attributable to this deficiency. Wild oily fish stocks are insufficient to feed the world's population, and levels of eicosapentaenoic acid and docosahexaenoic acid (DHA) in farmed fish have more than halved in the last 20 years. Here we report on a double-blinded, controlled trial, where 161 healthy normotensive adults were randomly allocated to eat at least three portions/week of omega-3-PUFA enriched (or control) chicken-meat, and to eat at least three omega-3-PUFA enriched (or control) eggs/week, for 6 months. We show that regular consumption of omega-3-PUFA enriched chicken-meat and eggs significantly increased the primary outcome, the red cell omega-3 index (mean difference [98.75% confidence interval] from the group that ate both control foods, 1.7% [0.7, 2.6]). Numbers of subjects with a very high-risk omega-3 index (index < 4%) were more than halved amongst the group that ate both enriched foods. Furthermore, eating the enriched foods resulted in clinically relevant reductions in diastolic blood pressure (- 3.1 mmHg [- 5.8, - 0.3]). We conclude that chicken-meat and eggs, naturally enriched with algae-sourced omega-3-PUFAs, may serve as alternative dietary sources of these essential micronutrients. Unlike many lifestyle interventions, long-term population health benefits do not depend on willingness of individuals to make long-lasting difficult dietary changes, but on the availability of a range of commonly eaten, relatively inexpensive, omega-3-PUFA enriched foods.

Association of Low-Dose Triple Combination Therapy With Therapeutic Inertia and Prescribing Patterns in Patients With Hypertension: A Secondary Analysis of the TRIUMPH Trial.

Importance: Fixed-dose combination (FDC) therapies are being increasingly recommended for initial or early management of patients with hypertension, as they reduce treatment complexity and potentially reduce therapeutic inertia. Objective: To investigate the association of antihypertensive triple drug FDC therapy with therapeutic inertia and prescribing patterns compared with usual care. Design, Setting, and Participants: A post hoc analysis of the Triple Pill vs Usual Care Management for Patients With Mild-to-Moderate Hypertension (TRIUMPH) study, a randomized clinical trial of 700 patients with hypertension, was conducted. Patients were enrolled from 11 urban hospital clinics in Sri Lanka from February 2016 to May 2017; follow-up ended in October 2017. Data were analyzed from September to November 2019. Interventions: Once-daily FDC antihypertensive pill (telmisartan, 20 mg; amlodipine, 2.5 mg; and chlorthalidone, 12.5 mg) or usual care. Main Outcomes and Measures: Therapeutic inertia, defined as not intensifying therapy in those with blood pressure (BP) above target, was assessed at baseline and during follow-up visits. Prescribing patterns were characterized by BP-lowering drug class and treatment regimen potency. Predictors of therapeutic inertia were assessed with binomial logistic regression. Results: Of the 700 included patients, 403 (57.6%) were female, and the mean (SD) age was 56 (11) years. Among patients who did not reach the BP target, therapeutic inertia was more common in the triple pill group compared with the usual care group at the week 6 visit (92 of 106 [86.8%] vs 124 of 194 [63.9%]; P < .001) and week 12 visit (81 of 90 [90%] vs 116 of 179 [64.8%]; P < .001). At the end of the study, 221 of 318 patients in the triple pill group (69.5%) and 182 of 329 patients in the usual care group (55.3%) reached BP targets. Among those who received treatment intensification, the increase in estimated regimen potency was greater in the triple pill group compared with the usual care group at baseline (predicted mean [SD] increase in regimen potency: triple pill, 15 [6] mm Hg; usual care, 10 [5] mm Hg; P < .001), whereas there were no significant differences at the week 6 or at week 12 visit. Clinic systolic BP level was the only consistent predictor of treatment intensification during follow-up. During follow-up, there were 23 vs 54 unique treatment regimens per 100 treated patients in the triple pill vs usual care groups, respectively (P < .001). Conclusions and Relevance: Triple pill FDC therapy was associated with greater rates of therapeutic inertia compared with usual care. Despite this, triple pill FDC therapy substantially simplified prescribing patterns and improved 6-month BP control rates compared with usual care. Further improvements in hypertension control could be achieved by addressing therapeutic inertia among the minority of patients who do not achieve BP control after initial FDC therapy. Trial Registration: ANZCTR Identifier: ACTRN12612001120864.

Dobutamine Stress Echocardiography Ischemia as a Predictor of the Placebo-Controlled Efficacy of Percutaneous Coronary Intervention in Stable Coronary Artery Disease: The Stress Echocardiography-Stratified Analysis of ORBITA.

BACKGROUND: Dobutamine stress echocardiography is widely used to test for ischemia in patients with stable coronary artery disease. In this analysis, we studied the ability of the prerandomization stress echocardiography score to predict the placebo-controlled efficacy of percutaneous coronary intervention (PCI) within the ORBITA trial (Objective Randomised Blinded Investigation With Optimal Medical Therapy of Angioplasty in Stable Angina). METHODS: One hundred eighty-three patients underwent dobutamine stress echocardiography before randomization. The stress echocardiography score is broadly the number of segments abnormal at peak stress, with akinetic segments counting double and dyskinetic segments counting triple. The ability of prerandomization stress echocardiography to predict the placebo-controlled effect of PCI on response variables was tested by using regression modeling. RESULTS: At prerandomization, the stress echocardiography score was 1.56±1.77 in the PCI arm (n=98) and 1.61±1.73 in the placebo arm (n=85). There was a detectable interaction between prerandomization stress echocardiography score and the effect of PCI on angina frequency score with a larger placebo-controlled effect in patients with the highest stress echocardiography score (Pinteraction=0.031). With our sample size, we were unable to detect an interaction between stress echocardiography score and any other patient-reported response variables: freedom from angina (Pinteraction=0.116), physical limitation (Pinteraction=0.461), quality of life (Pinteraction=0.689), EuroQOL 5 quality-of-life score (Pinteraction=0.789), or between stress echocardiography score and physician-assessed Canadian Cardiovascular Society angina class (Pinteraction=0.693), and treadmill exercise time (Pinteraction=0.426). CONCLUSIONS: The degree of ischemia assessed by dobutamine stress echocardiography predicts the placebo-controlled efficacy of PCI on patient-reported angina frequency. The greater the downstream stress echocardiography abnormality caused by a stenosis, the greater the reduction in symptoms from PCI. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02062593.

Fixed-combination, low-dose, triple-pill antihypertensive medication versus usual care in patients with mild-to-moderate hypertension in Sri Lanka: a within-trial and modelled economic evaluation of the TRIUMPH trial.

BACKGROUND: Elevated blood pressure incurs a major health and economic burden, particularly in low-income and middle-income countries. The Triple Pill versus Usual Care Management for Patients with Mild-to-Moderate Hypertension (TRIUMPH) trial showed a greater reduction in blood pressure in patients using fixed-combination, low-dose, triple-pill antihypertensive therapy (consisting of amlodipine, telmisartan, and chlorthalidone) than in those receiving usual care in Sri Lanka. We aimed to assess the cost-effectiveness of the triple-pill strategy. METHODS: We did a within-trial (6-month) and modelled (10-year) economic evaluation of the TRIUMPH trial, using the health system perspective. Health-care costs, reported in 2017 US dollars, were determined from trial records and published literature. A discrete-time simulation model was developed, extrapolating trial findings of reduced systolic blood pressure to 10-year health-care costs, cardiovascular disease events, and mortality. The primary outcomes were the proportion of people reaching blood pressure targets (at 6 months from baseline) and disability-adjusted life-years (DALYs) averted (at 10 years from baseline). Incremental cost-effectiveness ratios were calculated to estimate the cost per additional participant achieving target blood pressure at 6 months and cost per DALY averted over 10 years. FINDINGS: The triple-pill strategy, compared with usual care, cost an additional US$9·63 (95% CI 5·29 to 13·97) per person in the within-trial analysis and $347·75 (285·55 to 412·54) per person in the modelled analysis. Incremental cost-effectiveness ratios were estimated at $7·93 (95% CI 6·59 to 11·84) per participant reaching blood pressure targets at 6 months and $2842·79 (-28·67 to 5714·24) per DALY averted over a 10-year period. INTERPRETATION: Compared with usual care, the triple-pill strategy is cost-effective for patients with mild-to-moderate hypertension. Scaled up investment in the triple pill for hypertension management in Sri Lanka should be supported to address the high population burden of cardiovascular disease. FUNDING: Australian National Health and Medical Research Council.

Computational simulations of thrombolysis in acute stroke: Effect of clot size and location on recanalisation.

Acute ischaemic stroke can be treated by intravenous thrombolysis whereby tissue plasminogen activator (tPA) is infused to dissolve clots that block blood supply to the brain. In this study, we aim to examine the influence of clot location and size on lysis pattern and recanalisation by using a recently developed computational modelling framework for thrombolysis under physiological flow conditions. An image-based patient-specific model is reconstructed which consists of the internal carotid bifurcation with the A1 segment of anterior cerebral arteries and M1 segment of middle cerebral arteries, and the M1 bifurcation containing the M2 segments. By varying the clot size and location, 7 scenarios are simulated mimicking thrombolysis of M1 and M2 occlusions. Our results show that initial breakthrough always occurs along the inner curvature of the occluded cerebral artery, due to prolonged tPA residence time in the recirculation zone. For a given occlusion site, lysis completion time appears to increase almost quadratically with the initial clot volume; whereas for a given clot volume, the simulated M2 occlusions take up to 30% longer for complete lysis compared to the corresponding M1 occlusions.

Identification of Distinct Arterial Waveform Clusters and a Longitudinal Evaluation of Their Clinical Usefulness.

Clustering of arterial blood pressure (BP) waveform parameters could summarize complex information into distinct elements, which could be used to investigate cumulative (nonredundant) associations. We investigated this hypothesis in a large, adult population-based study (ViDA trial [Vitamin D Assessment] trial). To interpret the clusters and evaluate their usefulness, we examined their predictors and associations with cardiovascular events. In 4253 adults (mean age 65 years; 55% male) without a prior cardiovascular event, suprasystolic oscillometry was performed, yielding aortic pressure waveforms and several hemodynamic parameters. Participants were followed up for 4.6 years (median), accruing 300 cardiovascular events. Principal component analysis reduced 14 arterial waveform parameters to 3 uncorrelated factors that together explained 90% of the variability of the original data. Factors 1, 2, and 3 appeared to represent BP pulsatility, mean BP, and wave reflection, respectively. Across 6 antihypertensive drug classes, there were no differences in brachial systolic (P=0.23) and diastolic (P=0.13) BP; but there were significant variations in factor 3 (P<0.0001), especially for ß-blocker use. The first and third factors were positively associated with cardiovascular events (multivariable-adjusted standardized hazard ratio [95% CI]=1.33 [1.18-1.50] and 1.15 [1.02-1.30], respectively), whereas the second factor had a J-shaped relationship, with a nadir corresponding to a brachial diastolic BP of ≈75 mm Hg. In conclusion, BP pulsatility, mean BP, and wave reflection are prognostically meaningful, distinct aspects of arterial function that can be used to summarize physiological variations in multiple arterial waveform parameters and identify truly cumulative associations when used as cardiovascular risk outcomes.

Automatic optic disc detection in colour fundus images by means of multispectral analysis and information content.

The optic disc (OD) in retinal fundus images is widely used as a reference in computer-based systems for the measurement of the severity of retinal disease. A number of algorithms have been published in the past 5 years to locate and measure the OD in digital fundus images. Our proposed algorithm, automatically: (i) uses the three channels (RGB) of the digital colour image to locate the region of interest (ROI) where the OD lies, (ii) measures the Shannon information content per channel in the ROI, to decide which channel is most appropriate for searching for the OD centre using the circular Hough transform. A series of evaluations were undertaken to test our hypothesis that using the three channels gives a better performance than a single channel. Three different databases were used for evaluation purposes with a total of 2,371 colour images giving a misdetection error of 3% in the localisation of the centre of the OD. We find that the area determined by our algorithm which assumes that the OD is circular, is similar to that found by other algorithms that detected the shape of the OD. Five metrics were measured for comparison with other recent studies. Combining the two databases where expert delineation of the OD is available (1,240 images), the average results for our multispectral algorithm are: TPR = 0.879, FPR = 0.003, Accuracy = 0.994, Overlap = 80.6% and Dice index = 0.878.

Mathematical Modelling of Intravenous Thrombolysis in Acute Ischaemic stroke: Effects of Dose Regimens on Levels of Fibrinolytic Proteins and Clot Lysis Time.

Thrombolytic therapy is one of the medical procedures in the treatment of acute ischaemic stroke (AIS), whereby the tissue plasminogen activator (tPA) is intravenously administered to dissolve the obstructive blood clot. The treatment of AIS by thrombolysis can sometimes be ineffective and it can cause serious complications, such as intracranial haemorrhage (ICH). In this study, we propose an efficient mathematical modelling approach that can be used to evaluate the therapeutic efficacy and safety of thrombolysis in various clinically relevant scenarios. Our model combines the pharmacokinetics and pharmacodynamics of tPA with local clot lysis dynamics. By varying the drug dose, bolus-infusion delay time, and bolus-infusion ratio, with the FDA approved dosing protocol serving as a reference, we have used the model to simulate 13 dose regimens. Simulation results are compared for temporal concentrations of fibrinolytic proteins in plasma and the time that is taken to achieve recanalisation. Our results show that high infusion rates can cause the rapid degradation of plasma fibrinogen, indicative of increased risk for ICH, but they do not necessarily lead to fast recanalisation. In addition, a bolus-infusion delay results in an immediate drop in plasma tPA concentration, which prolongs the time to achieve recanalisation. Therefore, an optimal administration regimen should be sought by keeping the tPA level sufficiently high throughout the treatment and maximising the lysis rate while also limiting the degradation of fibrinogen in systemic plasma. This can be achieved through model-based optimisation in the future.

An activated-platelet-sensitive nanocarrier enables targeted delivery of tissue plasminogen activator for effective thrombolytic therapy.

It remains a major challenge to develop a selective and effective fibrinolytic system for thrombolysis with minimal undesirable side effects. Herein, we report a multifunctional liposomal system (164.6 ±â€¯5.3 nm in diameter) which can address this challenge through targeted delivery and controlled release of tissue plasminogen activator (tPA) at the thrombus site. The tPA-loaded liposomes were PEGylated to improve their stability, and surface coated with a conformationally-constrained, cyclic arginine-glycine-aspartic acid (cRGD) to enable highly selective binding to activated platelets. The in vitro drug release profiles at 37 °C showed that over 90% of tPA was released through liposomal membrane destabilization involving membrane fusion upon incubation with activated platelets within 1 h, whereas passive release of the encapsulated tPA in pH 7.4 PBS buffer was 10% after 6 h. The release of tPA could be readily manipulated by changing the concentration of activated platelets. The presence of activated platelets enabled the tPA-loaded, cRGD-coated, PEGylated liposomes to induce efficient fibrin clot lysis in a fibrin-agar plate model and the encapsulated tPA retained 97.4 ±â€¯1.7% of fibrinolytic activity as compared with that of native tPA. Furthermore, almost complete blood clot lysis was achieved in 75 min, showing considerably higher and quicker thrombolytic activity compared to the tPA-loaded liposomes without cRGD labelling. These results suggest that the nano-sized, activated-platelet-sensitive, multifunctional liposomes could facilitate selective delivery and effective release of tPA at the site of thrombus, thus achieving efficient clot dissolution whilst minimising undesirable side effects.

Reaching cardiovascular prevention guideline targets with a polypill-based approach: a meta-analysis of randomised clinical trials.

OBJECTIVE: The aim of this study was to determine the effect of polypill-based care on the achievement of 2016 European Society of Cardiology (ESC) guideline targets for blood pressure (BP), low-density lipoprotein (LDL) cholesterol and antiplatelet therapy. METHODS: We conducted an individual participant data meta-analysis of three randomised clinical trials that compared a strategy using a polypill containing aspirin, statin and antihypertensive therapy with usual care in patients with a prior cardiovascular disease (CVD) event or who were at high risk of their first event. Overall, the trials included 3140 patients from Australia, England, India, Ireland, the Netherlands and New Zealand (75% male, mean age 62 years and 76% with a prior CVD event). The primary outcome for this study was the proportion of people achieving ESC guideline targets for BP, LDL and antiplatelet therapy. RESULTS: Those randomised to polypill-based care were more likely than those receiving usual care to achieve recommended targets for BP (62% vs 58%, risk ratio (RR) 1.08, 95% CI 1.02 to 1.15), LDL (39% vs 34%, RR 1.13, 95% CI 1.02 to 1.25) and all three targets for BP, LDL and adherence to antiplatelet therapy (the latter only applicable to those with a prior CVD event) simultaneously (24% vs 19%, RR 1.27, 95% CI 1.10 to 1.47) at 12 months. There was no difference between groups in antiplatelet adherence (96% vs 96%, RR 1.00, 95% CI 0.98 to 1.01). There was heterogeneity by baseline treatment intensity such that treatment effects increased with the fewer the number of treatments being taken at baseline: for patients taking 3, 2 and 0-1 treatment modalities the RRs for reaching all three guideline goals simultaneously were 1.10 (95% CI 0.94 to 1.30, 22% vs 20%), 1.62 (95% CI 1.09 to 2.42, 27% vs 17%) and 3.07 (95% CI 1.77 to 5.33, 35% vs 11%), respectively. CONCLUSIONS: Polypill-based therapy significantly improved the achievement of all three ESC targets for BP, LDL and antiplatelet therapy compared with usual care, particularly among those undertreated at baseline.

Computational Simulations of Thrombolytic Therapy in Acute Ischaemic Stroke.

Ischaemic stroke can occur when an artery to the brain is blocked by a blood clot. The use of thrombolytic agents, such as tissue plasminogen activator (tPA), to dissolve the occluding clot is limited by the risk of intracerebral haemorrhage (ICH), a known side effect associated with tPA. We developed a computational thrombolysis model for a 3D patient-specific artery coupled with a compartmental model for temporal concentrations of tPA and lysis proteins during intravenous infusion of tPA, in order to evaluate the effects of tPA dose on the efficacy of thrombolytic therapy and the risk of ICH. The model was applied to a 3-mm-long fibrin clot with two different fibrin fibre radii in the middle cerebral artery (MCA) - a setting relevant to ischaemic stroke, and results for different tPA dose levels and fibrin fibre radii were compared. Our simulation results showed that clot lysis was accelerated at higher tPA doses at the expense of a substantial increase in the risk of ICH. It was also found that a fine clot with a smaller fibre radius dissolved much slowly than a coarse clot due to a slower tPA penetration into the clots.

Randomized Crossover Trial of the Impact of Morning or Evening Dosing of Antihypertensive Agents on 24-Hour Ambulatory Blood Pressure.

Some data suggest that nocturnal dosing of antihypertensive agents may reduce cardiovascular outcomes more than daytime dosing. This trial was designed to evaluate whether ambulatory blood pressure monitoring levels differ by timing of drug dosing. Patients aged 18 to 80 years with reasonably controlled hypertension (≤150/≤90 mm Hg) on stable therapy of ≥1 antihypertensive agent were recruited from 2 centers in London and Thessaloniki. Patients were randomized to receive usual therapy either in the morning (6 am-11 am) or evening (6 pm-11 pm) for 12 weeks when participants crossed over to the alternative timing for a further 12 weeks. Clinic blood pressures and a 24-hour recording were taken at baseline, 12, and 24 weeks and routine blood tests were taken at baseline. The study had 80% power to detect 3 mm Hg difference in mean 24-hour systolic blood pressure (α=0.05) by time of dosing. A 2-level hierarchical regression model adjusted for center, period, and sequence was used. Of 103 recruited patients (mean age, 62; 44% female), 95 patients (92%) completed all three 24-hour recordings. Mean 24-hour systolic and diastolic blood pressures did not differ between daytime and evening dosing. Similarly, morning and evening dosing had no differential impact on mean daytime (7 am-10 pm) and nighttime (10 pm-7 am) blood pressure levels nor on clinic levels. Stratification by age (≤65/≥65 years) or sex did not affect results. In summary, among hypertensive patients with reasonably well-controlled blood pressure, the timing of antihypertensive drug administration (morning or evening) did not affect mean 24-hour or clinic blood pressure levels. Clinical Trial Registration- URL: http://www.clinicaltrials.gov . Unique identifier: NCT01669928.