Short summary

Coronary CT angiography (CCTA) is a safe and accurate non-invasive method for evaluation of patients with suspected coronary artery disease (CAD). However, its ability to discriminate hemodynamic significant lesions is hampered in moderate CAD, and in the presence of severe calcifications. Based on the detailed anatomic information provided by CCTA, it is possible to estimate the functional significance of lesions using advanced computational fluid dynamics (FFR-CT). However, limited data exist on the diagnostic performance of FFR-CT in patients with severe calcifications. In this study we aim to assess if CTCA with FFR-CT in patients with severe coronary calcifications can differentiate between patients with and without obstructive CAD and if useful will result in a reduction of the number of subsequent ICAs.

---

Rationale

Approximately 10 years ago CT coronary angiography (CTCA) was introduced in Denmark as a non-invasive method for evaluation of patients with suspected coronary artery disease (CAD). It was expected that the availability of CTCA would result in a lowering of the need for invasive coronary angiography (ICA). However, this expectation has not been fulfilled, as the number of ICAs performed has not been reduced. Neither has the frequency of ICAs without obstructive CAD been reduced. A possible explanation for this observation may be that the availability of CTCA has resulted in more healthy persons being studied.

Recently a new promising diagnostic modality, CTCA with fractional flow reserve measurement (FFR-CT), has been introduced for clinical use.

From a patient perspective CTCA has the following advantages as compared with ICA

1. Lower radiation exposure and less discomfort
2. Reduced risk of complications, as CTCA is a non-invasive procedure

Also, it has been reported that patients, who have had both CTCA and ICA performed, actually do prefer CTCA. Indeed, all the issues outlined are of importance, but in a time with limited fiscal resources for public services, it is essential to document that the introduction of a new diagnostic method actually will reduce the need for already available modalities including ICA and myocardial perfusion scintigraphy - and not just become "one additional" method that will increase the total costs associated with the evaluation of patients with suspected CAD. Finally, it is well known that a number of patients have severe coronary artery calcifications, and this remains a major challenge in the interpretation of standard CTCA imaging, since severe coronary artery calcifications do decrease the diagnostic accuracy. In this study we aim to assess if CTCA with FFR-CT in patients with severe coronary artery calcifications can differentiate between patients with and without obstructive CAD and if useful will result in a reduction of the number of subsequent ICAs.

---

Description of the cohort

All patients with suspected stable CAD evaluated by CCTA at a study center providing informed consent fulfilling the inclusion and exclusion criteria are eligible.

Inclusion criteria:

1. Clinical stable patients with symptoms of suspected angina pectoris referred for CTCA
2. Age 18 years or older.
3. An estimated likelihood for the presence of significant CAD between 15% and 85%
4. Coronary Artery Score >399.

Exclusion criteria to CTCA:

1. Prior myocardial infarction, treatment with coronary stents, or coronary bypass surgery
2. Pregnancy
3. Contrast allergy
4. Inability to undergo CTCA
5. Severe renal failure
6. Atrial fibrillation

Collaborating researchers and departments

Department of Cardiology, Odense University Hospital

• Professor Hans Mickley
• Tina Svenstrup Poulsen, MD, PhD, MPM
• Assciate Professor, Axel Diederichsen, MD, PhD
• Kristian Altern Øvrehus, MD, PhD
• Associate Professor Lisette Okkels, MD, PhD
• Karsten Vejen, MD

Department of Cardiology, Odense University Hospital, Svendborg

• Jess Lambrecthsen, MD, PhD

Department of Cardiology, Lillebælt Hospital, Vejle

• Flemming Hald Steffensen, MD, PhD

Department of Cardiology, Esbjerg Hospital

• Dilek Akkan, MD