Coronary Artery Function in Patients with PAH: A Pilot Study.
Research type
Research Study
Full title
Coronary Artery Function in Patients with Known or Suspected Idiopathic Pulmonary Arterial Hypertension: A Pilot Study.
IRAS ID
157839
Contact name
C Berry
Contact email
Sponsor organisation
Golden Jubilee National Hospital / National Waiting Times Board
Duration of Study in the UK
1 years, 6 months, 31 days
Research summary
Summary of Research
High blood pressure in the lungs, known as Pulmonary Hypertension, is due to either a problem in the lungs themselves (namely Idiopathic Pulmonary Arterial Hypertension (IPAH)) or as a consequence of another health problem. Heart problems are the major cause of death in these patients.The cause of heart-related deaths has been attributed to changes in the structure and function of heart muscle cells in part due to a reduced oxygen supply and high lung blood pressures. Abnormalities in heart artery function are also suspected of contributing to the early and excess mortality in IPAH, but this aspect has not been investigated.
Pressure and temperature-sensitive diagnostic guide wires (nearly as thin as a human hair) enable direct assessment of heart artery function by measurement of the Coronary Flow Reserve (CFR), the Index of Myocardial Resistance (IMR) and the Resistive Reserve Ratio (RRR). We hypothesise that abnormalities exist heart artery function in patients with IPAH even if the angiogram (x-ray pictures of the heart arteries) appears normal. We propose a ‘proof of concept’ pilot study in 14 patients with IPAH (both newly diagnosed and established patients) who are scheduled to have clinically-indicated invasive assessment of heart, lung and peripheral blood vessel function.
Following informed consent, the study participants would have heart blood pressure measurements (right and left heart chambers) as per standard care. The pressure wire would be passed into the three main heart arteries CFR, IMR and RRR will be calculated in each artery using well established protocols. We will also assess tissue blood vessel density using a simple hand-held video microscope (placed under the tongue for a few seconds). These pilot results will inform further research into heart artery function in patients with lung blood vessel disease, and also provide feasibility data for grant applications to support the research.Summary of Results
In this study of patients with high blood pressure in the lungs, we assessed whether small blood vessels in the heart might also be affected.Sixteen patients were enrolled and 11 completed the protocol. The average age was 45 years and 73% were female. The level of functional limitation as assessed by the World Health Organisation functional class was: I / II/ III/ IV - 2 (18%), 6 (55%), 3 (27%), 0. The mean distance achieved during the 6-minute walk test was 282±145 metres. Coronary artery disease was apparent in 2 (18%) patients and no patients had a blocked coronary artery. There were 8 (73%) and 6 (55%) patients with abnormal increases in small blood vessel 'resistance' or impaired function, respectively, in any heart vessel. In this pilot study, we have found that abnormal small blood vessel function in the heart is common in patients with pulmonary hypertension. These findings merit further study.
REC name
West of Scotland REC 4
REC reference
15/WS/0134
Date of REC Opinion
7 Aug 2015
REC opinion
Further Information Favourable Opinion