Previous chapters have demonstrated the important role of myocardial perfusion imaging (MPI) for the diagnosis and risk stratification of coronary artery disease (CAD) in the general population. There is also robust literature validating the use of MPI in different patient cohorts. This chapter will describe the value of MPI for the assessment of CAD and risk stratification in special populations consisting of diabetic patients, women, patients with chronic renal disease, the elderly, and patients with acute chest pain syndromes.
EVALUATION OF DIABETIC PATIENTS
In 2014, the global prevalence of diabetes was estimated to be 9% among adults aged 18+ years by the World Health Organization (WHO).1 In the United States, the Centers for Disease Control (CDC) estimates those with diabetes is rising, with recently 29 million people (9.3% prevalence) suffering from diabetes.2 This increase in prevalence of diabetes mirrors the obesity epidemic in the United States with 33% of the population now classified as being obese.3 The overall prevalence of CAD has been estimated to be as high as 55% in diabetic patients compared with 4% in the general population. In a landmark Finnish observational trial, the authors elegantly demonstrated the similar survival (15.4% vs. 15.9%) and rate of myocardial infarction (MI) (20.2% vs. 18.8%) among diabetic patients without prior MI and nondiabetic patients with prior MI, respectively, leading to the designation of diabetes as CAD equivalent by the Adult Treatment Panel-III (ATP-III) guidelines.4,5 There are also data demonstrating that these patients have a higher incidence of more severe disease and are at greater risk of developing acute coronary syndromes.6 From these data it is clear that diabetic patients are at high risk for coronary events. Nuclear cardiology imaging offers potential for early and accurate identification of such patients.
The Role of Stress Myocardial Perfusion Imaging in Symptomatic Diabetic Patients
Stress MPI in symptomatic diabetic patients can be very beneficial in providing the appropriate diagnosis and risk stratification. Several studies demonstrate similar sensitivity (80–86%) and specificity (79–87%) of single-photon emission computed tomography (SPECT) MPI in diabetic patients as compared to nondiabetic patients.7,8 In the largest study to date, Kang et al.9 evaluated retrospectively 138 diabetics and 188 nondiabetics with suspected CAD who had SPECT imaging and coronary angiography within 6 months. The diagnostic accuracy was similar between diabetic and nondiabetic patients (p = nonsignificant), respectively. The normalcy rate for low-likelihood patients was 89% in diabetics and 90% in nondiabetics (p = NS). These data indicate a strong diagnostic role for MPI in diabetic patients which is not different from a nondiabetic cohort.
Risk Stratification in Diabetic Patients with Stress Myocardial Perfusion Imaging
Several studies have reported the value of SPECT MPI for the risk stratification of diabetic patients. In a single-center prospective study of ...