STRESS-ONLY IMAGING; A NEW PARADIGM FOR PERFORMING STRESS MYOCARDIAL PERFUSION IMAGING
John J. Mahmarian, M.D., Houston Methodist DeBakey Heart and Vascular Center, Houston, Texas, USA
Background: There have been continued efforts over the past several years to utilize a patient-centered imaging approach when performing stress myocardial perfusion imaging (MPI). One such approach has been to choose a single day stress/rest imaging strategy so that if the stress study is normal, rest imaging is unnecessary. By performing so–called “stress-only imaging”, radiation exposure to the patient can be markedly reduced by avoiding the higher rest radiopharmaceutical dose. In addition stress-only imaging affords improved laboratory efficiency, conservation of Tc-99m radiotracers, convenience for the patient and reduction in cost by eliminating the higher rest radiotracer dose.
Methods/Results: Several recent studies have determined the safety of stress-only imaging. In a study by our group, 16,854 patients with a normal stress MPI were followed for a median of 4.5 years with the primary endpoint of all-cause mortality. Event rates were similar in those who underwent stress-only (n=8,034) vs. stress-rest (n=8,820) MPI, and irrespective of gender, coronary artery disease status, stressor utilized or history of diabetes mellitus. In addition 60% of subjects received < 5mSv radiation dose with stress-only imaging. Similar findings were observed by Duvall et al. In a recent randomized study, we compared cardiac computed tomography (CTA) to stress MPI in low to intermediate risk patients evaluated in the emergency department with chest pain of uncertain cardiac etiology. By utilizing stress-only imaging, radiation exposure was significantly less with MPI vs. CTA (10.9+ 4.4 vs. 12.7+4.9mSv, p<0.001) with no difference in hospital cost, time to diagnosis or diagnostic accuracy.
Conclusion: A stress-rest MPI protocol affords the use of stress-only imaging which enhances patient throughput with less radiation exposure without sacrificing long term patient safety.