Inappropriate SPECT MPI scans more common in women

By Wayne Forrest, AuntMinnie.com contributing writer

April 28, 2016 -- Women are more likely than men to have an inappropriate SPECT myocardial perfusion imaging (MPI) scan, partly due to atypical symptoms, which may overestimate the true health risk to the female patient.

Based on the findings, researchers from the University of Florida suggested that an exercise treadmill test for women may be a viable option for diagnosing their symptoms, rather than proceeding further to SPECT MPI. The study results were presented at the recent American College of Cardiology (ACC) annual meeting.

"Oftentimes, providers feel that women have atypical symptoms, and that concerns them," lead author Dr. Ali Alsamarah, an assistant professor in the department of internal medicine, told AuntMinnie.com. "However, that swings the pendulum too far, and we felt they are overordering the tests because they don't know if these symptoms are cardiac-related or not."

Unnecessary testing

For many years, there has been much discussion about waste in healthcare, and a large part of the concern centers on the number and appropriateness of tests ordered by healthcare providers.

"Most commonly, we see this in tests such as echocardiograms and nuclear stress tests," Alsamarah said.

To address the issue and guide providers on when to order imaging tests, both the American College of Radiology (ACR) and the ACC have developed and refined appropriate use criteria for specific clinical conditions.

Still, whether inappropriate imaging occurs more often in women than men for cardiology applications is not fully known, the authors noted. One theory is that clinicians simply may be unsure if a female patient's symptoms are cardiac-related.

In this study, researchers focused on SPECT because of the radiation exposure to patients.

"The risk comes from multiple tests over many years, and although the risk is minimal, some of these tests can be avoided," Alsamarah said.

Retrospective review

The researchers reviewed 1,475 cases, of which 747 patients (51%) were women, and compared cardiovascular outcomes of individuals with suspected or known coronary artery disease. The subjects underwent SPECT MPI in both inpatient and outpatient settings between June 2011 and September 2014.

The cases were separated according to gender and appropriateness categories consisting of "appropriate," "maybe appropriate," or "rarely appropriate" scans.

A total of 180 (12%) MPI scans could be classified as rarely appropriate, Alsamarah and colleagues found. This group consisted of 118 women (16%) versus only 62 men (8%) (p < 0.0001).

Appropriateness of SPECT MPI studies, women vs. men
Appropriateness Women Men Total
Appropriate 581 (78%) 596 (82%) 1,177 (80%)
Maybe appropriate 48 (6%) 70 (9%) 118 (8%)
Rarely appropriate 118 (16%) 62 (8%) 180 (12%)

Of the rarely appropriate tests in women, 58 cases (49%) were due to low pretest probability that the individual had cardiac disease, which means an exercise treadmill test would have sufficed, rather than recommending SPECT MPI.

Alsamarah said SPECT MPI likely was chosen because of concerns regarding a woman's atypical or prolonged symptoms.

"But they could have been managed appropriately by having an exercise tolerance test done," he said.

Interestingly, women were less likely to have an abnormal MPI scan: 101 women (16%) had abnormal results, compared with 182 men (25%) (p < 0.0001).

MPI outcomes

The researchers also found no statistically significant difference in the rates of angiography between the two genders. There were 52 procedures performed in women (7%), compared with 67 in men (9%).

Still, Alsamarah said the finding represents a "considerable number of angiographies" for female patients.

"That is probably due to more concerns and more persistent symptoms, even though some were more atypical, but providers thought angiography would be the best option," he said.

Revascularization rates were lower in women, with seven procedures in women (1%), compared with 21 in men (3%) (p = 0.006).

The fewer revascularizations among women mean they had a lower rate of coronary artery disease, Alsamarah surmised.

Clinical outcomes after SPECT MPI
Outcome Women Men Total
Abnormal test 102 (14%) 183 (25%) 285 (19%)
Ischemia 63 (8%) 81 (11%) 144 (10%)
Angiography 52 (7%) 67 (9%) 119 (8%)
Revascularization 7 (1%) 21 (3%) 28 (2%)

Alsamarah said the lesson to be learned from these findings is that the exercise tolerance test is a viable option for women to diagnose their symptoms before proceeding further to SPECT MPI.

"The future challenge is, how can we prevent inappropriate use?" he added. "We need better risk stratification. We don't want to miss women who have atypical symptoms, but we need to understand the literature that supports evidence-based practices."


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