None listed
Conditions
Brief summary
Heart attack is a major cause of death within the Australian community. Cholesterol blockages in the coronary arteries (the vessels supplying oxygen & nutrients to the heart muscle) are typically responsible for the heart attacks and best seen on a specialized X-ray test that involves injecting dye into these arteries (coronary angiography). Surprisingly, in approximately 10% of heart attack patients, angiography does not show any significant cholesterol blockages. This group of patients is referred to as MINOCA (Myocardial Infarction with NonObstructive Coronary Arteries). The question then arises as to what caused the heart attack in these MINOCA patients? Potential causes include cholesterol plaque rupture, coronary artery spasm or abnormal constriction of the coronary microscopic vessels (coronary microvascular dysfunction). The aim of this study is to determine how often patients with MINOCA have evidence of cholesterol plaques or coronary microvascular dysfunction. Understanding how often these occur and their relationship to heart muscle damages (as seen on cardiac MRI) and symptoms will assist us in developing future treatments for this condition. The microvascular dysfunction assessments and plaque composition assessments will be performed following the standard coronary angiogram procedure and cardiac MRI will be performed within 5 days of the initial admission. All participants will be given informed consent prior to the study participation.
Interventions
The study procedures will begin following the participant's coronary angiogram diagnostic procedure. The coronary angiogram will be participant's standard care whereas the combowire and Optical Coherence Tomography (OCT) assessments will be provided as part of this study procedure.
Combowire Assessments: A wire will be passed into one of the coronary arteries that will allow us to measure the pressure and blood flow down the artery. This method allows us to measure the function of the small (mi
The study procedures will begin following the participant's coronary angiogram diagnostic procedure. The coronary angiogram will be participant's standard care whereas the combowire and Optical Coherence Tomography (OCT) assessments will be provided as part of this study procedure. Combowire Assessments: A wire will be passed into one of the coronary arteries that will allow us to measure the pressure and blood flow down the artery. This method allows us to measure the function of the small (microscopic) arteries. Adenosine is the agent used to dilate the microscopic arteries. This agent is given intravenously through an intravenous cannula. This intravenous cannula is routinely put in an arm vein prior to a coronary angiogram. In addition to dilating the small microscopic (small) arteries. Adenosine will be given for 2 minutes and necessary angiographic images will be taken and hemodynamics assessments will be performed. Following which, Glyceryl trinitrate (GTN) will be administered as intra coronary injection and the additional angiographic image will be taken. OCT Assessments: The combo wire will be removed and the OCT catheter will be inserted and the contrast agent will be injected. The imaging will be done in about 3 seconds, and the entire coronary artery will be imaged. It would take approximately 15 minutes to complete combowire and OCT assessments. Cardiac magnetic resonance imaging (MRI) Assessments: Within 5 days of the participant's initial presentation, they will undergo a cardiac MRI procedure. This is part of the participant's routine clinical management Health Status Assessments: Study participants will then followed up to 12 Months (1 Month, 6 Months and 12 Months) will the quality of life assessment questionnaires via telephone.
Sponsors
The University of Adelaide
Eligibility
Sex/Gender
All
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
1) Patients presenting with the symptoms suggestive of acute non-ST elevation myocardial infarction (NSTEMI) will be approached to participate in this study. 2) Male/Female, Aged equal or above 18 years 3) Acute MI Criteria (Must meet both of the following criteria (a & b) a) Troponin I or T level greater than the 99th percentile of the upper reference limit (URL) b) No significant ST segment elevation in ECG 4) Coronary angiography diagnosis of non-obstructive coronary arteries ( less than 50% stenosis or completely normal arteries)
Exclusion criteria
1) ST-segment elevation on ECG (ie: STEMI) 2) Thrombolytic therapy within 48 hours of diagnostic angiography. 3) Troponin elevation due to non-ischaemic causes identified prior to coronary angiography 4) Coronary angiography revealing obstructive coronary arteries (above or equal to 50% stenosis) 5) Severe valvular disease – including aortic stenosis (valve gradient more than 50mmHg) mitral regurgitation (regurgitation extending to pulmonary veins), mitral stenosis (valve are less than 1cm2) 6) Significant left ventricular dysfunction as documented by an ejection fraction less than 40% 7) Severe obstructive airways – any prior admission to ICU or general hospital admission in past 12 months for infective exacerbation of airways disease. 8) Active internal bleeding or history of hemorrhagic diathesis (including heparin-induced thrombocytopenia) 9) Major surgery (eg: CABG) or trauma within the previous 6 weeks 10) Non-English speaking 11) Pregnancy 12) Inability to provide informed consent (Compromised mental status, e.g., dementia, too ill) 13) Currently a prisoner 14) Contraindications to drugs and devices (Adenosine, GTN, OCT wire, Combo wire)
Outcome results
None listed