Work

Cardiac Imaging for Risk Stratification in Diabetes

Year: 2007

Type: article

Abstract: HOW IS CAD DIAGNOSED?The "gold standard" for detection of CAD remains invasive angiography with vessel-selective contrast injection of the coronary arteries.Both spatial (0.2 mm) and temporal (5 ms) resolution of the technique are extremely high, and the degree of luminal narrowing can be quantified precisely.This is an invasive and expensive procedure with a small but definite risk for complications.Noninvasive testing is increasingly used to assess CAD, and multiple methods are now unavailable.These can be divided into functional imaging, which detects the hemodynamic consequences of CAD (i.e., ischemia), and anatomical imaging, which detects atherosclerosis and permits direct visualization of the coronary arteries. Functional imagingThe basis of functional imaging is the detection of CAD by assessing the hemodynamic consequences (i.e., ischemia) of CAD rather than direct visualization of the coronary arteries.A sequence of events occurs during induction of ischemia, referred to as "the ischemic cascade" (9).Early (within seconds) in the ischemic cascade, perfusion abnormalities occur, and systolic wall motion abnormalities follow within 10 -20 s.Electrocardiogram (ECG) changes and angina occur only at the end of the cascade.Accordingly, exercise ECG is predictably not the most sensitive technique, and its diagnostic accuracy has been demonstrated to be low in patients with diabetes (10).Conversely, abnormalities in perfusion and systolic wall motion are early markers of ischemia.While perfusion abnormalities should be the more sensitive of the two for assessment of ischemia, in daily practice both phenomena are similarly sensitive.A number of imaging techniques can assess myocardial perfusion, including nuclear techniques (i.e., positron emission tomography [PET] or single photon e m i s s i o n c o m p u t e d t o m o g r a p h y [SPECT]), first-pass perfusion imaging with magnetic resonance imaging (MRI), and myocardial contrast echocardiography.For assessment of systolic wall motion, the following techniques are used: two-dimensional stress echocardiogra-

Source: Diabetes Care

DOI: 10.2337/dc06-2094