Comprehensive assessment of coronary physiology (fractional flow reserve (FFR), coronary flow reserve (CFR) and index of microcirculatory resistance (IMR)) in patients with diabetes mellitus and coronary artery disease (CAD).

Background:

There is currently no data on invasive measurement of FFR, CFR and IMR in patients with diabetes mellitus. Studies such as RIPCORD has shown that using coronary angiography alone to guide revascularization strategy may be flawed in a significant proportion of patients.

Patients with diabetes mellitus are more likely to have diffuse CAD and microvascular disease. Current recommendation of invasive physiological assessment to guide percutaneous coronary intervention (PCI) is limited to FFR alone. This can be misleading in diffuse coronary artery disease and microvascular disease as both conditions are associated with higher FFR. The proportion of vessels which show discordance between FFR and CFR consistent with diffuse CAD and/or microvascular disease in patients has been shown to be as high as 30% in a study not exclusive to diabetics.

This is a pilot study of 50 patients referred for PCI based on angiographic stenosis of ≥50%. Comprehensive physiological assessment will be undertaken in target and non-target vessels to determine the prevalence of discordant FFR and CFR consistent with diffuse CAD and/or microvascular dysfunction in diabetics.

Methods:

1. Patients will receive an information sheet after initial invitation to participate in the study.
2. Written informed consent will be obtained.
3. Patients will undergo invasive assessment of FFR, CFR and IMR in non-target vessels.
4. An optical coherence tomography (OCT) study will be performed to correlate physiological parameters with intravascular imaging for diffuse atheromatous disease.
5. Patients will then undergo OCT and invasive assessment of FFR, CFR and IMR in the target vessel pre and post PCI.
6. Any change in FFR, CFR and IMR post PCI will be recorded.
7. All physiological parameters will be measured using the pressure wire from St. Jude Medical, USA (currently, Certus). Results will be grouped according to 4 possible permutations of FFR and CFR.

Inclusion Criteria:

• Diabetic patients with angina and/or evidence of myocardial ischemia (includes ACS patients but not STEMI)
• Willing and able to provide informed, written consent
• Diabetic patients with clinically indicated, abnormal PET scan
• Single or double vessel disease with coronary stenosis ≥50% referred for PCI

Exclusion Criteria:

• Significant left main stenosis ≥50% and/or triple vessel disease referred for CABG
• Recent STEMI (<5 days)
• Previous CABG
• LVEF ≤ 30% or cardiogenic shock
• Complex coronary anatomy preventing FFR/CFR measurement