Condition category
Circulatory System
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Not provided at time of registration

Trial website

Contact information



Primary contact

Prof Neil Poulter


Contact details

International Centre for Circulatory Health
59 North Wharf Road
W2 1PG
United Kingdom

Additional identifiers

EudraCT number number


Protocol/serial number

HTA 08/109/02; CRO 1644/ 01

Study information

Scientific title

An evaluation of the effect of an angiotensin-converting enzyme (ACE) inhibitor on the growth rate of small abdominal aortic aneurysms


AARDVARK (Aortic Aneurysmal Regression of Dilation: Value of Ace-inhibition on RisK)

Study hypothesis

To investigate the hypothesis that an angiotensin-converting enzyme (ACE)-inhibitor reduces abdominal aortic aneurysm (AAA) growth rate in a three-arm randomised controlled pilot trial. The three interventions are ACE-inhibition with perindopril versus equivalent blood pressure reduction with amlodipine (a calcium channel blocker) versus placebo. By comparing the effects in the perindopril and amlodipine arms, this design will permit an evaluation of any BP independent effects of perindopril.

More details can be found at:
Protocol can be found at:

Ethics approval

West London Research Ethics Committee 2, 29/11/2010, ref: 10/H0711/80

Study design

Single-blind multicentre placebo-controlled study

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details below to request a patient information sheet


Asymptomatic abdominal aortic aneurysm


This study will be performed at five investigational sites in the UK. This is a randomised, single-blind, multicentre, placebo-controlled study in participants with an systolic blood pressure (SBP) less than 150 mmHg either untreated or on treatment with certain pre-specified background anti-hypertensive medications. The pilot trial will have 3 arms, with patients being randomised to either perindopril (10 mg arginine salt daily) or placebo (primary comparison) or amlodipine (5 mg daily) (secondary comparison). The perindopril and amlodipine doses will have similar effects on blood pressure reduction and hence the secondary comparison will help to inform whether all/any benefits of perindopril are independent of BP reduction. If during the trial an individual patient's aneurysm should reach 5.5 cm in diameter, this patient will be referred back to the vascular surgeons in the normal surveillance programme. This assessment should take place within 2 weeks.

Follow up is 2 years.

Intervention type



Phase IV

Drug names

Perindopril, amlodipine

Primary outcome measure

Aneurysm growth rate, estimated using multilevel modelling. Patients will have their maximum anterior-posterior aneurysm diameter measured by ultrasonography at 3-monthly intervals, using a dedicated trial co-ordinator.

Secondary outcome measures

The three interventions are ACE-inhibition with perindopril versus equivalent BP reduction with amlodipine (a calcium channel blocker) versus placebo. By comparing the effects in the perindopril and amlodipine arms, this design will permit an evaluation of any BP independent effects of perindopril.

Modelling of time taken for the aneurysm to reach the threshold for intervention (5.5 cm) and formal comparison of the reproducibility of internal and external aneurysm diameters. Quality of life (Euroquol 5D) and health resource questionnaires will be administered after 12 and 24 months of follow up.

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Willing and able to give written informed consent
2. Men or women, aged at least 60 years
3. AAA 3 to 5.4 cm in diameter according to ultrasound measurement
4. Systolic blood pressure (SBP) less than 150 mmHg (unless they require and are already receiving an ACE-inhibitor or amlodipine 10 mg daily). For patients whose SBP is greater than 150 mmHg, a 6-week course of the diuretic indapamide SR (1.5 mg daily) will be given, with re-evaluation of BP in the 6th week. If the SBP falls to less than 150 mmHg on this medication subjects would then be eligible for randomisation into the study. If this diuretic treatment is not appropriate then 5 mg of amlodipine could be prescribed by the patients GP if not already taking this drug. This would be followed by a six week re-evaluation as above.

Participant type


Age group




Target number of participants

225 participants

Participant exclusion criteria

1. Patients who are already required to take either an ACE-inhibitor or a calcium channel blocker or Angiotensin II blocker (ARB) who cannot be converted to diuretic therapy and/or a 5 mg dose of amlodipine for control (i.e., SBP less than 150 mmHg) of their BP
2. Those with known renal artery stenosis (greater than 50%), or with a serum creatinine of greater than 180 µmol/L
3. Those unable to give informed consent
4. Those too frail to travel for 3-monthly surveillance
5. Any clinically significant medical condition which, in the opinion of the investigator, may interfere with the study results and or reduce life expectancy to less than 2 years
6. Participation in another trial of an investigational product or device within the previous 30 days
7. Known allergy or sensitivity to perindopril or amlodipine
8. Unable or unwilling to comply with the requirements of the study, in the opinion of the investigator

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

International Centre for Circulatory Health
W2 1PG
United Kingdom

Sponsor information


Imperial College London (UK)

Sponsor details

Faculty of Medicine
G02 Sir Alexander Fleming Building
South Kensington Campus
United Kingdom

Sponsor type




Funder type


Funder name

Health Technology Assessment Programme

Alternative name(s)

NIHR Health Technology Assessment Programme, HTA

Funding Body Type

government organisation

Funding Body Subtype

Federal/National Government


United Kingdom

Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date


Participant level data

Not provided at time of registration

Basic results (scientific)

Publication list

2016 results in:

Publication citations

Additional files

Editorial Notes

05/08/2016: Publication reference added.