Acute rest myocardial perfusion imaging in the emergency department: a technique whose time has come... or gone?

Stress myocardial perfusion imaging in the emergency department--new techniques for speed and diagnostic accuracy

Emergency room evaluations of patients presenting with chest pain continue to rise, and these evaluations which often include cardiac imaging, are an increasing area of resource utilization in the current health system. Myocardial perfusion imaging from the emergency department remains a vital component of the diagnosis or exclusion of coronary artery disease as the etiology of chest pain. Recent advances in camera technology, and changes to the imaging protocols have allowed MPI to become a more efficient way of providing this diagnostic information. Compared with conventional SPECT, new high-efficiency CZT cameras provide a 3-5 fold increase in photon sensitivity, 1.65-fold improvement in energy resolution and a 1.7-2.5-fold increase in spatial resolution. With stress-only imaging, rest images are eliminated if stress images are normal, as they provide no additional prognostic or diagnostic value and cancelling the rest images would shorten the length of the test which is of particular importance to the ED population. The rapid but accurate triage of patients in an ED CPU is essential to their care, and stress-only imaging and new CZT cameras allow for shorter test time, lower radiation doses and lower costs while demonstrating good clinical outcomes. These changes to nuclear stress testing can allow for faster throughput of patients through the emergency department while providing a safe and efficient evaluation of chest pain.

Acute resting myocardial perfusion imaging in patients with diabetes mellitus: results from the Emergency Room Assessment of Sestamibi for Evaluation of Chest Pain (ERASE Chest Pain) trial

BACKGROUND

Resting myocardial perfusion imaging (MPI) improves the triage of patients presenting to the emergency department (ED) with symptoms suggestive of acute cardiac ischemia (ACI). In the ED setting the presence of diabetes mellitus (DM) is a predictor of ACI and hospitalization, but the role of resting MPI in patients with DM is unknown.

METHODS AND RESULTS

A secondary data analysis of a prospective, multicenter, randomized, controlled trial of ED evaluation strategies in patients with symptoms suggestive of ACI and normal or nondiagnostic electrocardiograms was performed. In the main trial 2475 patients were randomized to receive either the usual ED evaluation strategy (n = 1260) or the usual strategy supplemented by results from resting MPI by use of single photon emission computed tomography (SPECT) technetium 99m sestamibi (n = 1215). Patients with diabetes (n = 341) were evaluated separately. Imaging results, final diagnoses, effect on triage, and prognostic value of the SPECT imaging were compared between diabetic and nondiabetic patients. Of the 341 patients with diabetes, 153 (45%) were randomized to the imaging strategy. Patients with DM had higher rates of hospitalization (66% vs 49.6%, P = .0001) and ACI (21.1% vs 12.0%, P < .001) than patients without DM. Among diabetic patients without ACI, the admission rate was 63% in the usual strategy group versus 54% in the imaging strategy group (relative risk [RR] = 0.91 [95% CI, 0.76-1.06]; P = .24). There was no difference in the magnitude of this reduced risk of admission compared with patients without DM (RR = 0.84 [95% CI, 0.77-0.92]; P = .0002 for patients without DM and P = .35 for interaction of diabetes and RR reduction).

CONCLUSIONS

Acute resting MPI with Tc-99m sestamibi is associated with improved triage decision making in symptomatic ED patients with diabetes.