None listed
Conditions
Brief summary
The purpose of our study is to improve the identification of the lesion responsible in patients presenting with NSTEMI (a form of heart attack), as these patients often can have multiple lesions and our ability to identify the culprit is still limited. All patients participating in this study will undergo a heart MRI before their scheduled invasive coronary angiogram to identify the area damaged by the heart attack. They will then proceed to scheduled coronary angiogram as planned. After the angiographic images are obtained, further anatomical and functional information of the heart vessels will be obtained with advanced intracoronary imaging (using OCT) and coronary physiology measurements (FFR, CFR, IMR). We will then see if the interrogation of this further information can help operators in identifying the correct artery responsible for the heart attack.
Interventions
All patients presenting with non-ST elevation myocardial infarction (NSTEMI) and referred to the cardiac catheterization laboratory of two tertiary hospitals are eligible for recruitment. All patients will undergo cardiac magnetic resonance (CMR) prior to invasive coronary angiography (ICA) to identify the location of myocardial infarction. Contrast-enhanced CMR is performed with intravenous gadolinium, with cine and delayed enhancement imaging as per standard hospital protocols. Left ventricula
All patients presenting with non-ST elevation myocardial infarction (NSTEMI) and referred to the cardiac catheterization laboratory of two tertiary hospitals are eligible for recruitment. All patients will undergo cardiac magnetic resonance (CMR) prior to invasive coronary angiography (ICA) to identify the location of myocardial infarction. Contrast-enhanced CMR is performed with intravenous gadolinium, with cine and delayed enhancement imaging as per standard hospital protocols. Left ventricular function and volumes will be assessed by standard steady-state free precession technique. Short- and long-axis views will be acquired. Aortic flow maps will be acquired to confirm volumes. For contrast enhanced images, short-axis slices will be obtained by injecting 0.2 mmol/kg gadolinium at 2 mL/s followed by a 20 mL saline flush into an antecubital vein. Early gadolinium enhancement images are acquired 1-2 minutes after injection. Short axis stack images will be obtained. Late gadolinium enhancement images are acquired 10 minutes after contrast injection. Inversion time will be optimised to null normal myocardium. Left ventricular function, volumes and mass will be calculated. Microvascular obstruction is defined as an area of hypo-enhancement within the gadolinium hyper-enhanced area of infarcted tissue which is present early after contrast injection and persistent on late enhancement images. The CMR will take approximately 45 minutes and be performed in the radiology department of the hospital. The test is performed by an experienced radiographer under supervision of a qualified radiologist. ICA is subsequently performed as per standard protocol. After ICA, all 3 major epicardial coronary arteries will be further interrogated with optical coherence tomography (OCT), fractional flow reserve (FFR), coronary flow reserve (CFR), the index of microcirculatory resistance (IMR), and plaque temperature. OCT is performed using the Dragonfly Optis Coronary optical coherence tomography system catheter as per standard hospital protocol. FFR, CFR, IMR, and plaque temperature are measured using the PressureWire X intravascular haemodynamic monitoring system guidewire as per standard hospital protocol. ICA, OCT, and coronary physiology measurements are performed in the cardiac catheter laboratory of the study hospital by an experienced interventional cardiologist. Total procedure time is expected to be approximately 75 minutes. All patients will undergo the interventions mentioned above once during the course of the study. All interventions will take place on the same day within 24 hours of each other. All steps will be guided and tracked by an associate investigator using a checklist to monitor adherence.
Sponsors
Royal Prince Alfred Hospital
Study design
Allocation
Non-randomised trial
Intervention model
Single group
Primary purpose
Diagnosis
Masking
Blinded (masking used) (Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
All
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
1) Patient age greater than or equal to 18 years, willing and able to give consent 2) NSTEMI defined as appropriate rise and fall of troponin, with at least one value above the 99th percentile and absence of ST-segment elevation, together with one of the following: • Symptoms of myocardial ischemia • New ischemic ECG changes • Imaging evidence of new loss of viable myocardium or new regional wall motion abnormality in a pattern consistent with an ischemic etiology
Exclusion criteria
1) Cardiogenic shock, defined as systolic blood pressure < 90mmHg, or need for inotropic support to maintain adequate blood pressure. 2) Previous MI 3) Previous coronary artery bypass grafting surgery or PCI 4) Glomerular filtration rate < 30 mL/min/1.73 m2 5) Contraindication to CMR 6) Contraindication to adenosine 7) Alternative explanation for troponin rise 8) Pregnancy 9) Excessive tortuosity of coronary vessels that precludes safe passage of pressure wire/OCT catheter 10) Ongoing symptoms/ischemia refractory to medical therapy, which necessitates urgent coronary angiography
Outcome results
None listed