SPECT-MPI in the PCP setting still offers high prognostic value

SPECT-myocardial perfusion imaging (SPECT-MPI) performed at a low-volume primary care physician’s (PCP’s) office has robust prognostic value in line with what is reported in tertiary or high-volume practice settings, according to a study published March 9 in Journal of Nuclear Cardiology.

While studies have shown the prognostic value of SPECT-MPI—patients with normal MPI have an annual risk of less than 1 percent for major adverse cardiovascular events—those studies were conducted in larger tertiary or high-volume centers, explained Rami Doukky, MD, MSc, of Rush University Medical Center in Chicago, and colleagues. Mobile cardiac SPECT imaging equipment has made the technique easier to conduct in a PCP’s office, but little was known about the value of studies in this setting or whether PCPs would consistently follow appropriate use criteria.

Doukky and colleagues conducted a prospective cohort study of 1,390 consecutive patients referred by their PCP to undergo a stress-MPI in the PCP’s office using a mobile laboratory. The study cohort included patients from 10 private primary care practices comprising 20 physicians from the Chicago metropolitan area, and patients were followed for 27 months, with major adverse cardiovascular event tracked with interviews, chart reviews and social security death index data.

Results showed that for the 174 patients with abnormal MPI, there were significantly higher rates of all-cause mortality, death or myocardial infarction. Risk of major adverse cardiovascular event was associated with total perfusion abnormality burden.

“The study confirms that patients with normal MPI performed in this setting are at a very low annualized risk of death (0.32 percent) and death or MI (0.54 percent),” wrote the authors.

Despite maintaining high prognostic value with SPECT-MPI, the authors noted that the PCPs in the study had a high rate of non-adherence to 2009 appropriate use criteria for the procedure. The 47 percent non-adherence rate was even higher than previous studies of non-adherence, which have shown an approximately 20 percent rate of non-adherence among non-cardiologists. The authors suggested that the low risk of the tested population led to the high inappropriate use rate.

Doukky and colleagues added that “this study further emphasizes the role of the [appropriate use criteria] as an important quality measure in the laboratory accreditation process, which has already been implemented by the Intersocietal Accreditation Commission. Furthermore, this study emphasizes the need for national organizations of primary care to educate their members about the [appropriate use criteria].”