July 22nd, 2013
Studies Raise Questions About Echocardiography
Echocardiography is a safe, noninvasive tool to image the heart without the use of radiation. For this reason it has become the most frequently used method to look at the heart for a wide variety of medical indications. Now two new studies suggest that, despite its popularity, transthoracic echocardiography is often not beneficial. One study finds that in most cases echocardiography does not change the treatment of patients. A second study suggests that using echocardiography to screen low-risk people for heart disease is not warranted.
In the first study, published in JAMA Internal Medicine, Susan Matulevicius and colleagues reviewed the patient records for 535 consecutive standard echocardiograms performed at their hospital (the University of Texas Southwestern Medical Center) in one month. Although the vast majority of cases were indicated according to current appropriate use criteria (AUC) — 91.8% were deemed appropriate, only 4.3% were deemed inappropriate, and 3.9% were deemed uncertain — less than a third of cases resulted in an active change in care:
- active change in care: 31.8%
- continuation of current care: 46.9%
- no change in care: 21.3%
There were no significant differences between the three groups in the rate of appropriate usage. The authors concluded:
“The discrepancy between appropriateness and clinical impact is striking and suggests that the AUC as currently implemented are unlikely to facilitate optimal use oftransthoracic echocardiography (TTE). Given the importance of responsible use of limited medical resources and the need to control increasing health care costs, additional research into the necessity of TTE in the process of medical care is needed…”
In an invited commentary, William Armstrong and Kim Eagle note that in some situations echocardiography is appropriate and beneficial “even when expected to result in no change in therapy in most patients.” One example they cite is the use of echocardiography in patients with suspected pulmonary hypertension in which echocardiography “is the only realistic method for confirming its presence or absence.” They agree, however, that the current AUC “are not without remaining flaws and ideally should result in a categorization scheme that can be demonstrated to have a consistent, but not necessarily invariable, effect on medical decision making.”
In a second invited commentary, John Ionnidis agrees that a test may still have “some value when it reassures that the current management plan is fine.” However, he observes, in more than a fifth of cases echocardiography was “performed for no apparent reason: no active change was made, and there was no evidence that the test provided any reassurance to stay the same course.”
Ionnidis goes on to observe that “active changes in management…are only a modest surrogate of usefulness.” He points out that an echocardiogram “may have led to an active change” but this may have introduced new complications. Similarly, staying the course can be either useful or harmful. “…simply creating a list of appropriate indications will not mean their use leads to patient benefit,” he writes. He calls for more randomized controlled trials of diagnostic testing.
Screening A General Population
In the second paper, also published in JAMA Internal Medicine, Norwegian researchers studied nearly 7,000 people who were already participating in the Tromsø observational study. The patients were randomized to receive an echocardiography screening examination or to a control group and were then followed for 15 years. Of the screening group patients, 7.6% ultimately received a diagnosis of a cardiac or valvular disorder.
There were no significant differences in the rate of death between the two groups (26.9% in the screening group versus 27.6% in the control group) or in any of the secondary outcome measures. The investigators reported a significant reduction in death associated with screening in the subgroup of participants with a family history of early MI. At 15 years the rate of death for this subgroup was 23.5% in the screening groups versus 28.1% in the control group, although this difference was no longer significant after adjusting for multiple comparisons. The authors wrote that “the magnitude of absolute mortality difference (4.7%) is implausible because only 11.3% of the screened participants in this subgroup had pathologic findings on echocardiography.”
The Norwegian investigators said that their finding “supports existing guidelines that echocardiography is not recommended for cardiovascular risk assessment in asymptomatic adults.” The results “are of clinical importance because they may contribute to reducing the overuse of echocardiography.” They noted that although echocardiography “is noninvasive and does not involve irradiation, unwarranted screening is not without caveat… incidental findings on the echocardiogram may result in anxiety, psychological harm, and unwarranted complications, with little clinical benefit.” In an invited commentary, Erin Michos and Theodore Abraham further note that patients may be “falsely reassured” by a normal echocardiogram, because it is not able to exclude coronary artery disease.