The use of myocardial perfusion imaging (MPI) has declined over the past few years, researchers wrote in a letter published March 26 in JAMA. The decrease, they explained, could be due to changing physician behavior as well as a lower incidence of coronary disease.
Researchers led by Edward J. McNulty, MD, of Kaiser Permanente Medical Center in San Francisco, used data from patients who underwent MPI between 2000 and 2011 at Kaiser Permanente Northern California. They calculated age- and sex-adjusted annual rates of MPI tests per 100,00 person years. In order to determine whether other testing modalities could have been substituted for MPI, they estimated annual rates of cardiac CT and stress echocardiography.
The overall rate of MPI was 302,506 tests during the 23.2 million person-years of follow-up. Between 2000 and 2006, MPI use increased by 41 percent. However, between 2006 and 2011, use declined by 51 percent. The decrease was not related to sex or revascularization history, but was greater among outpatients than inpatients and for patients younger than 65 years.
The use of stress echocardiography did not change over the study years (189 per 100,000 person years in 2007 and 182 per 100,000 person years in 2011), while cardiac CT use did (37 per 100,000 person years in 2007 and 73 per 100,000 person years). The increase in CT use could have accounted for 5 percent of the MPI decline if used as a substitution.
Additionally, incident MI decreased by 27 percent at the same time MPI use declined (286 per 100,000 person years to 208 person years).
Although the MPI decline occurred in a system that does not offer financial incentives for testing, the authors noted that the “substantial reduction in MPI use demonstrates the ability to reduce testing on a large scale with anticipated reductions in healthcare costs."