Clinical trial NCT02043535: CO2 as a Stress Agent for Perfusion Imaging
Official title: Effects of Controlled Hypercapnic Stimulation on Myocardial Blood Flow Measured With Positron Emission Tomography
Study type: INTERVENTIONAL
Overall status: TERMINATED
Phase: NA
Conditions: Coronary Artery Disease
Keywords: myocardial perfusion imaging
myocardial blood flow
pharmacologic stress agents
carbon dioxide
rubidium 82 radioisotope
positron emission tomography
Lead sponsor: Ottawa Heart Institute Research Corporation
Sponsor class: OTHER
First posted: 2014-01-23
Enrollment: 20
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: NA
Intervention model: SINGLE_GROUP
Primary purpose: DIAGNOSTIC

Brief summary: Myocardial perfusion imaging (MPI) is a nuclear scan using a radioisotope to see blood flow to the muscles of the heart when the heart is at rest and when it is under stress. The stress test in MPI can be done using medications, such as persantine, that dilate coronary arteries and increase blood flow. Similarly, elevated carbon dioxide (CO2) levels in the blood, or hypercapnia, also dilates arteries and increases blood flow. Thornhill Research Inc. has developed the RA-MR™ sequential gas delivery system used to control CO2 levels in the blood. The RA-MR™ can deliver precise amounts of CO2 through a mouthpiece for inhalation to increase CO2 levels in the blood and thereby increasing blood flow like during stress.

The objective of this study is to compare the differences in blood flow through the arteries of the heart during stress with hypercapnia and adenosine MPI. The imaging will be done using positron emission tomography (PET) with the radioisotope, or tracer, called Rubidium (Rb-82). The Rb-82 is given through a pump, or elution system.

The investigators hypothesize that hypercapnia will induce a stress-to-rest increase in myocardial blood flow by a factor of 2 or more in myocardial regions supplied by non-stenotic arteries in normal volunteers and participants with coronary artery disease.


Eligibility criteria: Inclusion Criteria:

For all participants

* Age ≥ 18 years old
* BMI ≤ 40 kg/m2
* Able and willing to comply with the study procedures
* Written informed consent
* Participants with documented coronary artery disease
* Stable coronary artery disease on a stable medication regime.
* Healthy volunteers without known heart disease
* Low risk of coronary artery disease (CAD)

Exclusion Criteria:

* History or risk of severe bradycardia (heart rate \< 50 beats per minute) not related to chronotropic drugs
* Known second- or third-degree Atrio-ventricular block without pacemaker
* Atrial flutter or atrial fibrillation
* Dyspnea (NYHA III/IV), wheezing asthma or Chronic Obstructive Pulmonary Disease (COPD)
* Coronary artery bypass graft (CABG) surgery within 60 days prior to screening or at any time after consent
* Percutaneous coronary intervention (PCI) within 30 days prior to screening or at any time following consent
* Acute myocardial infarction or acute coronary syndrome within 60 days prior to screening or at any time following consent
* Recent use of dipyridamole, dipyridamole-containing medications (e.g. Aggrenox)
* Known hypersensitivity to adenosine
* Breastfeeding or pregnancy
* Claustrophobia or inability to lie still in a supine position
* Unwillingness or inability to provide informed consent

Primary outcomes:
measure: Myocardial blood flow differences
timeFrame: Difference between baseline rest scan blood flow and hypercapnia stress scan myocardial blood flow at 50 mmHg, 55 mmHg, 60 mmHg levels from baseline. Imaging and intervention analysis will be complete in 4 years.
Secondary outcomes:
measure: Absolute myocardial blood flow differences between end-tidal CO2 scans
timeFrame: Difference between baseline and 60 mmHg PetCO2. Imaging and intervention analysis will be complete in 4 years.
measure: Difference bewteen absolute myocardial blood flow with hypercapnia and with adenosine stress.
timeFrame: Quantification and comparison of the differences in myocardial blood flow with adenosine stress and increasing levels of CO2 as a stress agent. Imaging and intervention analysis will be complete in 4 years.
Other outcomes:
Locations:
city: Ottawa
country: Canada
facility: University Of Ottawa Heart Institute
state: Ontario
Study officials:
affiliation: Ottawa Heart Institute Research Corporation
name: Terrence D Ruddy, MD
role: PRINCIPAL_INVESTIGATOR
References: