Patients determined to have a normal-appearing initial stress SPECT do not require additional rest imaging as they have a similar low mortality rate as those who undergo stress and rest imaging, according to new findings to be published in the Jan. 19 issue of the Journal of the American College of Cardiology.
Su Min Chang, MD, and colleagues at Methodist DeBakey Heart and Vascular Center in Houston evaluated whether a normal stress-only SPECT study confers the same prognosis as a normal SPECT on the basis of stress and rest images in 16,854 consecutive patients with a follow-up of 4.5 years.
A stress-only protocol was used in 8,034 patients (47.6 percent) in the retrospective study, whereas 8,820 patients (52.4 percent) had both stress and rest imaging.
“After adjustment for baseline clinical characteristics, no significant differences in patient mortality were seen between the two imaging protocols, but the stress-only group received a 61 percent lower radiopharmaceutical dosage,” wrote Chang.
Chang and colleagues noted that there was a significant reduction in the radiopharmaceutical dose received by patients who had stress-only imaging (21.3 mCi) versus those who underwent additional rest imaging (55.1mCi), and this was particularly true in the 62 percent of patients who received a low dose of Tc-99m on their stress-only exam (13.5 mCi).
“Patients determined to have a normal SPECT on the basis of stress imaging alone have a similar low mortality rate as those who undergo stress and rest imaging. Our results support that patients who have a normal-appearing initial stress SPECT do not require additional rest imaging. This imaging strategy will significantly reduce radiation exposure in a substantial number of patients,” concluded the authors.
The limitations of the study were that it was a retrospective study and the information on the cause of death or the frequency of other nonfatal cardiac events were not available. However, raw mortality rates were consistently lower in the stress-only group and across all patient subgroups, according to the authors.
In an accompanying editorial, Ami Iskandrian, MD, professor of medicine in the department of radiology at the University of Alabama at Birmingham, wrote: "The health costs, radiation dose and patient comfort demand that we become flexible in our selection of imaging protocols; the status quo is no longer tenable. This change in imaging protocol combined with recent and future developments should radically change the perception that myocardial perfusion imaging is an all-day procedure.”
“The American College of Cardiology, the American Society of Nuclear Cardiology, the Centers for Medicare and Medicaid Services and the third-party payors should make note of this new paradigm in imaging, because it is applicable to a sizable proportion of patients, and its impact on cost and safety is substantial,” added Iskandrian.