Background:
Current evidence and guidelines in nuclear cardiology support the use of stress-only myocardial perfusion imaging (SO-MPI), without rest imaging, to decrease radiation dose to the patient. We sought to determine the downstream utilization of cardiac procedures in patients undergoing SO-MPI in comparison to those undergoing rest-stress myocardial perfusion imaging (RS-MPI). Demonstration of the decreased need for cardiac procedures following SO-MPI would increase the confidence of interpreting nuclear cardiologists and referring physicians.
Methods:
We retrospectively analyzed the nuclear cardiology database at Allegheny General Hospital for patients undergoing stress testing with MPI from Jan 2010 to June 2011. Selection criteria for SO-MPI in our laboratory, includes no prior history of revascularization and low pre-test probability of coronary artery disease (CAD) based on symptoms and risk factors. We analyzed the rate of follow-up cardiac catherizations and repeat stress testing upto12 months after the index stress MPI. We compared the rate of procedure utilization following SO-MPI and RS-MPI.
Results:
A total of 5269 stress tests were performed during the enrollment period, of which 829 (16%) underwent SO-MPI, and the remainder (n=4440, 84%) had RS-MPI. Abnormal MPI was more likely in patients undergoing RS-MPI vs SO-MPI (525 vs 5; p<0.05). Patients undergoing RS-MPI were more likely to have a follow-up procedure compared to those undergoing SO-MPI (odds ratio 2.5; p<0.0001). Specifically the rate of cardiac catherization (565/4440; 13% in RS-MPI vs 27/829; 3%in SO-MPI p<0.05) and the rate of repeat stress testing (177/4440; 4% in RS-MPI vs 15/829; 1.8% in SO-MPI, p<0.05) were significantly higher in the RS-MPI group. Among patients undergoing SO-MPI, rate of cardiac catherization was significantly higher in patients having follow-up rest images compared to those that did not (odds ratio: 12.5, p<0.001). There were 6 revascularizations in the SO-MPI group in the follow-up period of which 5 occurred in those with abnormal MPI and 1 occurred in a patient with normal SO-MPI but in the setting of an acute infarct.
Conclusions:
Downstream procedure utilization following a SO-MPI strategy is low. This complements the low mortality rate noted in this population by prior studies. It further confirms that the current selection criteria for SO-MPI is appropriate as most patients require only one image and do not need additional testing. In patients with low-intermediate pretest probability for CAD that are referred for MPI, SO-MPI with limited use of rest imaging can facilitate throughput, reduce patient radiation dose and is associated with appropriately low downstream utilization.
DOES HEMODYNAMIC RESPONSE DURING REGADENOSON STRESS MYOCARDIAL PERFUSION IMAGING PREDICT PRESENCE OR ABSENCE OF ISCHEMIA ?
