Magnetic Resonance Diabetic Cardiac Stress Imaging

Overview

The aim of the study is to assess the efficacy of cardiac MRI to detect coronary disease in diabetic patients. Cardiac MRI will be compared to myocardial scintigraphy with is the method being used in current practice. The investigators believe that cardiac MRI will be as efficient if not better that myocardial scintigraphy to detect tight coronary artery stenosis with the advantage of providing no radiation to the patient. Moreover, the investigators believe that cardiac MR will add additional information regarding possible undetected myocardial infarction.

Rationale: The incidence of diabetes is rising constantly. According to the WHO projections, the population of diabetics will double by 2025. In France, the current population of diabetics is estimated at 2.5 millions persons. The cause of death in diabetics involves a cardiovascular condition in approximately 65-80% of the cases. The leading event is myocardial infarction. The prevalence of silent myocardial ischemia (SMI) in diabetics varies widely from 10 to 30%. The prognosis of SMI is closely dependent on the presence or not of angiographically significant coronary artery stenosis - CAS (patients with SMI and CAS\>70% show 31% of major cardiac events at 41±24 months vs only 1.4% in patients with SMI and no CAS\>70%). It seems therefore important to identify diabetic patients with SMI and CAS especially knowing that endovascular or surgical treatments are available and can potentially improve the prognosis of such patients. Myocardial Perfusion Scintigraphy (MPS) is widely prescribed to detect coronary stenosis. It has a high sensitivity (90%) but an intermediate specificity (75%), providing a significant amount of false positive cases. Such false positive cases are usually followed with unnecessary coronary angiographies. Myocardial Perfusion Stress MRI (MRI) has been recently developed and shows promising preliminary results (equivalent sensitivity, higher specificity compared to MPS) for the identification of coronary artery stenosis. Few studies directly compare MRI and MPS in the general population, none in the diabetic population. Principal objective: To evaluate and compare diagnostic performances of MRI and MPS for the diagnosis of coronary insufficiency in diabetic patients free of known coronary disease. Secondary objective: * Cost efficacy analysis for the diagnosis of coronary insufficiency in diabetic patients free of known coronary disease. * Impact of clinical information on MRI and MPS diagnostic performances. Design:. Prospective, monocentric study, where MRI and MPS will be assessed in a centralised manner by 2 independent blinded readers (2 readers for each technique) and compared to coronary angiography (Gold Standard, assessed by 2 independent blinded readers). Patient selection: Patient with diabetes (type 1 or type 2), free of known coronary disease, addressed for MPS. Inclusion period length: 24 months Follow up period length: 2 days Principal judgement criteria: Coronary angiography: positive diagnosis of CAS if stenosis \>50% on the left coronary artery (trunk) or stenosis \>70% on the IVA (inter ventricular artery), LCx (circumflex artery) or RCA (right coronary artery) and branches. MPS : positive diagnosis of CAS based on the following criteria : severity perfusion index, reversibility, contractility anomalies, signal attenuation due to patient morphology. MRI : positive diagnosis of CAS based on an algorithm including the following criteria : first pass perfusion defect at stress, reversibility at rest, Myocardial Delayed Enhancement. Number of necessary patients: 165 Expected results: An assessment of MRI performances compared to MPS for the diagnosis of coronary insufficiency in diabetic patients free of known coronary disease that will help improve diagnostic strategy.

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