Prognostic value of a faster, low-radiation myocardial perfusion SPECT protocol in a CZT camera.

To determine the prognostic value of a new, ultrafast, low dose myocardial perfusion SPECT (MPS) protocol in a cadmium-zinc telluride (CZT) camera. CZT cameras have introduced significant progress in MPS imaging, offering high-quality images despite lower doses and scan time. Yet, it is unknown if, with such protocol changes, the prognostic value of MPS is preserved. Patients had a 1-day 99 m-Tc-sestamibi protocol, starting with the rest (185-222 MBq) followed by stress (666-740 MBq). Acquisition times were 6 and 3 min, respectively. MPS were classified as normal or abnormal perfusion scans and summed scores of stress, rest, and difference (SSS, SRS and SDS), calculated. Patients were followed with 6-month phone calls. Hard events were defined as death or nonfatal myocardial infarction. Late revascularization was that occurring after 60 days of MPS. 2930 patients (age 64.0 ± 12.1 years, 53.3% male) were followed for 30.7 ± 7.5 months. Mean dosimetry was 6 mSv and mean total study time, 48 ± 13 min. The annual hard event and late revascularization rate were higher in patients with greater extension of defect and ischemia. SSS was higher in patients with hard events compared to those without events (2.6 ± 4.9 vs. 5.0 ± 6.3, p < 0.001), as well as the SDS (0.7 ± 1.9 vs. 1.7 ± 3.4, p < 0.00). The same was true for patients with or without late revascularization (SSS: 2.5 ± 4.7 vs. 6.6 ± 7.1; SDS: 0.6 ± 1.7 vs. 2.9 ± 3.8, p < 0.01). A new, faster, low-radiation, MPS protocol in a CZT camera maintain the ability to stratify patients with increased risk of events, showing that, in the presence of greater extension of defect or ischemia, patients presented higher rates of hard events and late revascularization.

Prognostic Assessment of Diabetics Using Myocardial Perfusion Imaging: Diabetes Mellitus is Still a Coronary Artery Disease Equivalent.

BACKGROUND: Even though diabetes mellitus (DM) has been considered a "Coronary Artery Disease (CAD) equivalent", that is still controversial, especially in a contemporary population subject to optimized treatment. OBJECTIVE: We aimed to assess the cardiovascular risk of diabetics by myocardial perfusion scintigraphy (MPS). METHODS: Consecutive patients who underwent MPS from 2008 to 2012 were studied. Perfusion scores were calculated, and abnormal MPS was defined as a summed stress score >3. Patients were followed for 3±1 years for all-cause death, which was compared between patients with DM (without known CAD) and patients with known CAD but without DM. RESULTS: Among 3409 patients, 471 (13.8%) were diabetics without known CAD (DM group) and 638 (18.7%) had CAD without diabetes (CAD group). Annualized death rates were not significantly different between DM or CAD patients (0.9 vs 1.5%, p=0.09). With normal MPS, death rates were 0.7% for DM and 0.6% for CAD (p=0.8). With abnormal MPS, death rates increased similarly in the DM and CAD groups. CONCLUSIONS: In diabetic patients without known CAD, the rate of death was not significantly different from patients with prior CAD and without DM. Abnormal MPS increased risk similarly in diabetic patients and in those with CAD. These findings suggest that DM may still be considered a high-risk condition, comparable to known CAD, and effectively stratified by MPS.

"Metabolically healthy" obesity: Prevalence, clinical features and association with myocardial ischaemia.

OBJECTIVE: To evaluate the prevalence of the "metabolically healthy" (MH) or "metabolically unhealthy" (MU) obesity phenotypes and their association with cardiorespiratory fitness and inducible myocardial ischaemia. METHODS: Individuals without known coronary artery disease undergoing myocardial perfusion single-photon emission computed tomography (MPS) were studied. Those without dyslipidemia, hypertension, or diabetes were considered MH, and when ≥1 of these was present, MU status was considered present. Summed stress and difference perfusion scores (SSS and SDS, respectively) were calculated; a SDS >1 defined ischaemic MPS. RESULTS: MH patients were 35.0% of the nonobese population and 23.5% of the obese (p<0.001). The prevalence of ischaemia was not significantly different between MH patients with obesity or MH patients without obesity (10.9% vs 9.1%, p=0.3), except for patients with body mass index ≥40kg/m2 (21.9%). MH obese patients were less frequently able to exercise and had lower exercise capacity than the nonobese patients. CONCLUSIONS: The prevalence of myocardial ischaemia was not significantly different between MH obese or nonobese individuals, supporting the concept of the "metabolically healthy obesity". However, there are other factors involved, such as the ability to exercise, that influence the risk of myocardial ischaemia, limiting the "safety" of that obesity phenotype.