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Trial registered on ANZCTR
Registration number
ACTRN12617000983303
Ethics application status
Approved
Date submitted
30/06/2017
Date registered
10/07/2017
Date last updated
13/08/2019
Date data sharing statement initially provided
13/08/2019
Type of registration
Prospectively registered
Titles & IDs
Public title
The causes of bradycardia in athletes
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Scientific title
The effects of ivabradine under autonomic blockade in endurance athletes.
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Secondary ID [1]
292315
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Nil known
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Universal Trial Number (UTN)
U1111-1198-5373
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Trial acronym
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Linked study record
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Health condition
Health condition(s) or problem(s) studied:
Bradycardia in athletes
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Condition category
Condition code
Cardiovascular
303217
303217
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0
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Other cardiovascular diseases
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Intervention/exposure
Study type
Interventional
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Description of intervention(s) / exposure
Intervention:
Autonomic blockade with single doses of intravenous metoprolol(0.2mg/kg) + intravenous atropine (0.04mg/kg) plus oral ivabradine 15mg
Exposure: endurance sport participation
A wash out period of at least 24 hours will occur before crossover to the control arm
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Intervention code [1]
298488
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Treatment: Drugs
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Intervention code [2]
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Lifestyle
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Comparator / control treatment
Control:
Autonomic blockade with single doses of intravenous metoprolol(0.2mg/kg) + intravenous atropine (0.04mg/kg) plus plus placebo (methylcellulose capsule)
Exposure control: non endurance sport athletes
A wash out period of at least 24 hours will occur before crossover to the
intervention arm
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Control group
Placebo
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Outcomes
Primary outcome [1]
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Heart rate at rest on ECG
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Assessment method [1]
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Timepoint [1]
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30 minutes following administration of autonomic blockade + ivabradine or placebo
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Primary outcome [2]
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Peak heart rate on ECG monitoring
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Assessment method [2]
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Timepoint [2]
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During VO2 max test 30 minutes after administration of autonomic blockade + ivabradine or placebo (immediately after resting ECG)
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Secondary outcome [1]
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Change in left ventricular end diastolic volume on echocardiography at rest
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Assessment method [1]
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Timepoint [1]
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One hour following administration of autonomic blockade + ivabradine or placebo precrossover
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Secondary outcome [2]
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Change in BNP on serum assay post exercise
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Assessment method [2]
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Timepoint [2]
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Immediately following administration of autonomic blockade + ivabradine or placebo and VO2 max test
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Secondary outcome [3]
336615
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Change in right ventricular end diastolic volume on echocardiography at rest
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Assessment method [3]
336615
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Timepoint [3]
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One hour following administration of autonomic blockade + ivabradine or placebo pre crossover
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Secondary outcome [4]
336616
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Change in left ventricular end diastolic volume on MRI at rest
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Assessment method [4]
336616
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Timepoint [4]
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One hour following administration of autonomic blockade + ivabradine or placebo post cross over
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Secondary outcome [5]
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Change in right ventricular end diastolic volume on MRI at rest
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Assessment method [5]
336617
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Timepoint [5]
336617
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One hour following administration of autonomic blockade + ivabradine or placebo post cross over
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Secondary outcome [6]
336618
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Change in right ventricular end diastolic volume on exercise MRI at maximal exercise
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Assessment method [6]
336618
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Timepoint [6]
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One hour following administration of autonomic blockade + ivabradine or placebo post cross over (immediately post rest MRI)
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Secondary outcome [7]
336619
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Change in right ventricular end diastolic volume on exercise MRI at maximal exercise
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Assessment method [7]
336619
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Timepoint [7]
336619
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One hour following administration of autonomic blockade + ivabradine or placebo post cross over (immediately post rest MRI)
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Secondary outcome [8]
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Change in right ventricular end diastolic volume on exercise echocardiography at maximal exercise
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Assessment method [8]
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Timepoint [8]
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One hour following administration of autonomic blockade + ivabradine or placebo pre crossover (immediately post rest echocardiogram)
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Secondary outcome [9]
336622
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Change in left ventricular end diastolic volume on exercise echocardiography at maximal exercise
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Assessment method [9]
336622
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Timepoint [9]
336622
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One hour following administration of autonomic blockade + ivabradine or placebo pre crossover
(immediately post rest echocardiogram)
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Secondary outcome [10]
336623
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Change in maximal left atrial volume on exercise echocardiography at maximal exercise
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Assessment method [10]
336623
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Timepoint [10]
336623
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One hour following administration of autonomic blockade + ivabradine or placebo pre crossover
(immediately post rest echocardiogram)
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Secondary outcome [11]
336624
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Change in maximal left atrial volume on exercise MRI at maximal exercise
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Assessment method [11]
336624
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Timepoint [11]
336624
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One hour following administration of autonomic blockade + ivabradine or placebo post crossover
(immediately post rest MRI)
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Secondary outcome [12]
336625
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Change in PA pressure as measured by measuring tricupsid regurgitation velocity during maximal exercise on exercise echocardiography
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Assessment method [12]
336625
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Timepoint [12]
336625
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One hour following administration of autonomic blockade + ivabradine or placebo pre crossover
(immediately post rest echocardiogram)
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Eligibility
Key inclusion criteria
Group 1 (Endurance athletes): Competing in endurance sport
Group 2 (Healthy Volunteers): Less than three hours of exercise per week
Group 3 (Endurance athletes with bradycardia): Endurance athletes with a resting heart rate less than 40
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Minimum age
18
Years
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Maximum age
50
Years
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Sex
Both males and females
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Can healthy volunteers participate?
Yes
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Key exclusion criteria
1. Allergy to one of the medications
2. Asthma
3. Glaucoma
4. Urinary Retention/Prostate enlargement
5. Past history of psychosis
6. Ulcerative Colitis
7. Gastrointestinal Obstruction
8. Myasthenia gravis
9. Hypotension(low blood pressure
10. Smoker
11. Preexisting cardiac or lung disease
12. Pregnant or breast feeding
13. Contraindication to MRI
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Study design
Purpose of the study
Prevention
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Allocation to intervention
Randomised controlled trial
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Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Numbered containers
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Methods used to generate the sequence in which subjects will be randomised (sequence generation)
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Masking / blinding
Blinded (masking used)
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Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s
The people assessing the outcomes
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Intervention assignment
Crossover
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Other design features
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Phase
Phase 4
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Type of endpoint/s
Efficacy
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Statistical methods / analysis
The group sizes were calculated to be able to detect a change in heart rate of 10 beats per minute.
Baseline comparisons of continuous variables will be made between groups using independent samples t-tests. Categorical value comparisons will be made using chi square testing. Repeated measures will be analysed using repeated measures ANOVA.
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Recruitment
Recruitment status
Recruiting
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Date of first participant enrolment
Anticipated
10/07/2017
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Actual
18/07/2017
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Date of last participant enrolment
Anticipated
23/09/2019
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Actual
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Date of last data collection
Anticipated
30/09/2019
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Actual
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Sample size
Target
30
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Accrual to date
26
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Final
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Recruitment in Australia
Recruitment state(s)
VIC
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Recruitment hospital [1]
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Baker Heart and Diabetes Institute - Melbourne
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Recruitment postcode(s) [1]
16541
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3004 - Melbourne
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Funding & Sponsors
Funding source category [1]
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Government body
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Name [1]
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NHMRC
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Address [1]
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GPO Box 1421
Canberra ACT 2601
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Country [1]
296858
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Australia
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Primary sponsor type
Other
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Name
Baker Heart and Diabetes Institute
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Address
PO Box 6492, Melbourne Victoria 3004, Australia
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Country
Australia
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Secondary sponsor category [1]
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None
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Name [1]
295864
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Address [1]
295864
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Country [1]
295864
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Ethics approval
Ethics application status
Approved
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Ethics committee name [1]
298085
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Alfred Hospital Ethics Committee
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Ethics committee address [1]
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Old Baker Building, Level 1, 55 Commercial Rd, Melbourne VIC 3004
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Ethics committee country [1]
298085
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Australia
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Date submitted for ethics approval [1]
298085
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29/03/2017
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Approval date [1]
298085
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10/05/2017
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Ethics approval number [1]
298085
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138/17
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Summary
Brief summary
It is well known that athletes have lower heart rates (bradycardia) than non-athletes. This is generally considered a healthy adaptation. However, bradycardia has been associated with the subsequent development of atrial fibrillation (AF), an arrhythmia known to increase the risk of heart failure, stroke and even death. Consequently, bradycardia could conceivably be associated with significant problems later in life. The reasons athletes have slow heart rates are not well understood. Traditionally changes in neural input (vagal tone) were thought to lead to bradycardia in athletes. However, several studies have demonstrated that even after blocking these inputs(autonomic blockade), athletes continue to have lower heart rates than non-athletes. The reasons for this are not known however recent research using athlete mice models suggests this is due to intrinsic changes within the heart by downregulation of the HCN4 gene. In the mouse model, the medication which blocks this gene, ivabradine, helped to equalize the heart rates in athlete and non-athlete mice. Our aim in this study is to understand the reason for lower heart rates in endurance athletes. Participants will undergo repeat testing under experimental conditions to help determine the causes of low heart rates in athletes. We hypothesize that ivabradine will be less effective in athletes, ie it will lower the heart rate of athletes less than nonathletes. This would suggest that bradycardia in athletes is associated with changes within the heart rather than reversible changes in neural inputs. This may provide some insights into the mechanism of atrial fibrillation in athletes.
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Trial website
https://www.baker.edu.au/research/clinical-trials/endurance-athletes
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Trial related presentations / publications
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Public notes
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Attachments [1]
3088
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/AnzctrAttachments/373222-Advertisement V4 4.12.17.pdf
(Other)
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Contacts
Principal investigator
Name
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A/Prof Andre La Gerche
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Address
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Baker Heart and Diabetes Institute
Level 4, Alfred Centre
99 Commercial Road
Melbourne, VIC 3004
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Country
75946
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Australia
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Phone
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+61 3 8532 1143
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Fax
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Email
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[email protected]
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Contact person for public queries
Name
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Darragh Flannery
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Address
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Baker Heart and Diabetes Institute
Level 4, Alfred Centre
99 Commercial Road
Melbourne, VIC 3004
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Country
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Australia
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Phone
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+61 3 8532 1214
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Fax
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Email
75947
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[email protected]
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Contact person for scientific queries
Name
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Andre La Gerche
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Address
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Baker Heart and Diabetes Institute
Level 4, Alfred Centre
99 Commercial Road
Melbourne, VIC 3004
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Country
75948
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Australia
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Phone
75948
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+ 61 3 8532 1143
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Fax
75948
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Email
75948
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[email protected]
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Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
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No/undecided IPD sharing reason/comment
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What supporting documents are/will be available?
No Supporting Document Provided
Results publications and other study-related documents
Documents added manually
No documents have been uploaded by study researchers.
Documents added automatically
No additional documents have been identified.
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