Evaluation of the Functional Impact of Coronary Stenoses in Diabetics by Spectral CT

The optimal screening methods for coronary insufficiency, a frequent and pejorative complication in diabetics, are subject to debate, particularly in situations of silent myocardial ischemia. The contemporary strategy consists of pre-selecting asymptomatic patients at very high cardiovascular (CV) risk by performing a coronary calcium score. If this is found to be high \>300 AU (Agatston units), the patient is suspected of being at high risk of silent myocardial ischemia (SMI), and the assessment is completed to exclude the presence of coronary artery disease likely to benefit from revascularization.

The complementary evaluation consists in evaluating the myocardial perfusion to judge the perfusion repercussions. The most common examination to date is myocardial scintigraphy, because stress tests are too frequently submaximal in diabetics. However, the reproducibility of scintigraphy is controversial and their sensitivity and specificity are debated in this indication.

This problem is similar in stable symptomatic coronary diabetic patients for whom an indication for functional examinations is justified.

The double-energy double-layer spectral scanner (SDEDC) could now become a relevant tool in this field, since it can combine not only anatomical data (identification of coronary stenosis) but also functional data (myocardial perfusion) during a stress protocol. thanks to the spectral images which make it possible to measure the tissue concentration of intramyocardial iodine downstream of the considered stenosis.


Eligibility Criteria:
Inclusion Criteria:

* Aged man ≥50 years old or woman aged ≥55 years old, (age difference justified for established menopause which increases the CV risk and to avoid the risk of CT scan during pregnancy)
* Diabetic (type 1 or type 2 or type 3):
* Asymptomatic, falling within the scope of screening for silent myocardial ischemia and having a CAC \> 300 AU or
* Symptomatic on the coronary level, within the framework of the evaluation of symptomatic coronary insufficiency with positive myocardial scintigraphy.
* Patient having agreed to participate in the study and signed a written informed consent
* Patient affiliated to a social security scheme or similar

Exclusion Criteria:

Drug intolerance (adenosine, and/or contrast product used (Iomeron))

Related to iodine injection:

* History of major immediate or delayed skin reaction + hypersensitivity to the active substance or to any of the excipients
* Renal failure with GFR \< 45 ml/min -
* Known autonomic goiter with risk of thyrotoxicosis
* No suspension of the biguanide the same day of the examination (and resumed 48 hours later)

Linked to the injection of adenosine and regadenoson (Cf SPC Adenoscan combination with dipyridamole)

* 2nd or 3rd degree BAV not fitted, sinus dysfunction not fitted,
* Long QT syndrome,
* Decompensated heart failure,
* Unstable angina / Acute coronary syndrome / ATCD IDM less than a year old
* BP \> 1800 mmHg \< 100 mmHg
* Known stenosis of the common trunk (left),
* Tight heart valve stenosis.
* Uncorrected hypovolemia,
* Chronic obstructive pulmonary disease with clinical bronchospasm (e.g. bronchial asthma)
* Comitiality
* No suspension of dipyridamole (during the 48 hours before the examination)
* Severe hypotension
* Consumption of coffee, tobacco, tea, cola, banana, chocolate consumed before the examination (usual instructions in the event of myocardial stress protocol by adenosine agonist during the scintigraphy)
* Contraindication to adenosine: severe hypotension

Related to scanner performance

* patient unable to maintain apnea.
* Calcium score \> 500 on the common trunk
* Temporary suspension of bradycardia or anti-anginal on the day of the examination (beta blocker, calcium channel blocker) not carried out.

Related to the patient's context

* Person unable to express their consent.
* Patient under guardianship, curatorship or safeguard of justice