Stress echo beats CCTA for evaluating chest pain

By Kate Madden Yee, AuntMinnie.com staff writer

June 13, 2018 -- Stress echocardiography is a safe method of evaluating chest pain in patients who present to the emergency department, resulting in lower rates of hospitalization and shorter hospital stays when compared with coronary CT angiography (CCTA), according to a study published online June 13 in JACC: Cardiovascular Imaging.

The findings suggest that stress echo could be an effective alternative to CCTA for emergency department (ED) chest pain triage, reducing patients' radiation exposure and healthcare costs. But the modality is often disregarded as an option, wrote a team led by Dr. Jeffrey Levsky, PhD, from Albert Einstein College of Medicine in New York City.

"[Concerns] regarding CCTA use include radiation exposure, increased subsequent noninvasive testing ... increased catheterization and coronary revascularization of uncertain benefit, increased downstream clinical resource utilization, and the burden inherent to incidental findings," the group wrote. "Each of these concerns is addressed by the alternative use of stress echocardiography, a modality that has been assessed in early emergency department triage but is often overlooked."

Better assessment?

Cardiovascular disease causes one of three deaths worldwide, Levsky and colleagues wrote. Chest pain is a common reason patients present in the emergency department due to concerns that the pain signifies a heart attack. There are a number of ways to assess chest pain, but CCTA is quick and has been shown to reduce a patient's stay in the hospital compared to other modalities such as nuclear myocardial perfusion imaging (MPI)

Dr. Jeffrey Levsky, PhD, from Albert Einstein College of Medicine.

"We conducted this study because there are very few published trials that rigorously compare different ways to work up emergency department chest pain patients," Levsky told AuntMinnie.com. "Chest pain is such an important emergency presentation -- involving literally millions of Americans yearly -- but assessing it can take a lot of time and expense."

CCTA exposes patients to radiation, however, and it can prompt further procedures that may or may not be of benefit, the group noted. That's why stress echocardiography shows promise for evaluating chest pain in the emergency department, although it does have its challenges.

"Stress echo requires close coordination of the exercise and imaging parts and a good deal of patient cooperation," he said. "Critics of the technique feel it is too low in sensitivity. But on the other hand, it does not require radiation, and long-term outcomes are good when the test is negative."

Levsky and colleagues started with 400 low- to intermediate-risk acute chest pain patients who presented to the emergency department between August 2011 and January 2016 and randomized them to CCTA (201 patients) or stress echocardiography (199 patients). The patients had no known coronary artery disease and had negative initial serum troponin levels. The study's primary outcome measure was the hospitalization rate, while its secondary end point was the length of stay in the emergency department and/or the hospital. Of the subjects, 42.5% were women and 87.3% were ethnic minorities, the group wrote.

The researchers found that patients who underwent stress echocardiography had lower rates of hospitalization, shorter emergency department and hospital stays, and fewer adverse events on follow-up (although this last metric was not statistically significant).

Comparison of CCTA vs. stress echo for chest pain
Measure	CCTA	Stress echocardiography	Change	p-value
Hospitalized on arrival at ED	19%	11%	-8 percentage point change	0.026
Median ED stay	5.4 hours	4.7 hours	-13%	< 0.001
Median hospital stay	58 hours	34 hours	-41%	0.002
Adverse events over a median 24 months of follow-up	11	7	-36%	0.47
Median initial workup radiation exposure	6.5 mSv	None	-100%	N/A

"[Our study] provides the first comparison of CCTA and stress echocardiography in emergency department chest pain patients and shows a statistically significant 8% reduction of hospitalization in patients triaged with stress echocardiography compared to CCTA," the group wrote.

The researchers also found an overall trend toward less resource utilization over a 24-month follow-up period among patients who underwent stress echocardiography, although most measures did not reach statistical significance. There was no statistically significant difference between CCTA and stress echocardiography regarding subsequent catheterization and revascularization, and patients rated their experience with stress echocardiography more favorably than with CCTA.

An effective tool

Stress echocardiography appears to be a safe and effective tool for evaluating chest pain in the emergency department compared with CCTA, Levsky and colleagues wrote.

"Stress echocardiography resulted in the discharge of a significantly higher number of patients with significantly shorter lengths of stay, was safe at intermediate-term follow-up, and provided a better patient experience," they concluded.

Letters blast study linking ultrasound and autism

By Kate Madden Yee, AuntMinnie.com staff writer

June 11, 2018 -- A study published in February in JAMA Pediatrics that suggested a link between the incidence of autism spectrum disorder (ASD) and prenatal ultrasound is coming under fire by critics who are calling out the study's conclusion as oversimplified at best and inaccurate at worst

The original research, conducted by a team led by Dr. N. Paul Rosman of Boston Medical Center, claimed to find a statistically significant association between the development of ASD and one technical sonography parameter: the depth of ultrasound penetration for scans performed at certain points during pregnancy.

But this measure isn't valid, wrote Dr. Christoph Lees from the Imperial College Healthcare NHS Trust in London in a letter published online June 11, also in JAMA Pediatrics.

"The authors introduce a hitherto unheard-of index: the depth of ultrasonographic penetration," he wrote. "This has no clear biological or scientific justification. Nevertheless, they report that the mean depth of penetration of the ultrasound beam is greater in those who developed ASD than in healthy children. But depth of penetration of ultrasound is not a measure of ultrasonography exposure; it simply tells us how far the ultrasound beam reaches."

The study authors' conclusion that "further research is needed to determine whether other variables of ultrasound exposure also have adverse effects on the developing fetus" doesn't accurately reflect the data, he wrote.

"In apparent contravention of JAMA Pediatrics' guidance for reporting clinical studies of this nature, no recruitment flowchart with participant exclusion/inclusion criteria is shown, and neither a priori hypothesis, predefined primary outcome, nor sample size calculation are included," Lees wrote.

The study also drew criticism in a letter from Drs. David Somerset and Robert Wilson of the University of Calgary, who believe the study's conclusion that "greater ultrasonographic depth" negatively affects the fetus has not been proved and is a "gross oversimplification."

"The authors present no evidence that a mean difference of 4 mm in depth is associated with higher energy delivery to the fetus," they wrote. "Furthermore, clinical variables, such as maternal obesity and age and paternal age, are independently associated with ASD ... and these variables have not been accounted for. It is a shame that ... [the] study has such an alarmist conclusion in the abstract that is not supported by the study findings."

Because possible links between ultrasound and autism cause such anxiety among parents and pregnant women, it's crucial that studies are reported accurately, Lees concluded.

"In fact, this study shows that children with ASD were exposed to a shorter duration of prenatal ultrasonography and lower-energy scans than healthy children," he wrote. "These findings are reassuring. We respectfully suggest that a more accurate form of words would have reflected the study's finding than is found in the conclusion of the abstract.

BRR : New Doppler Index for Renal Artery Stenosis

POCUS helps medical students find more AAAs than surgeons

By Kate Madden Yee, AuntMinnie.com staff writer

June 1, 2018 -- With a bit of training, medical students using point-of-care ultrasound (POCUS) can identify more abdominal aortic aneurysms (AAAs) than vascular surgeons can by screening for the condition via physical exam, according to a study published online May 17 in the Annals of Vascular Surgery.

The findings not only confirm ultrasound's efficacy for this application but also suggest a new resource for AAA screening in an era when medical staff can be stretched thin, wrote the team led by Trinh Mai from the University of Ottawa.

"Screening for AAA has been found to be largely underutilized in the U.S., with only 15% of eligible and at-risk individuals receiving screening examinations," the researchers wrote. "To mitigate obstacles associated with access to screening [such as staff and device availability] ... the introduction of point-of-care ultrasound training at the medical student level, and its wide-scale implementation as an extension to physical examination, may lead to improved detection of AAA."

Ultrasound training

When untreated, abdominal aortic aneurysms have a mortality rate as high as 85% to 90%, Mai and colleagues wrote. Physical examination has low sensitivity and specificity, even when experienced physicians perform it.

Ultrasound is much more effective and is currently the primary imaging tool used to screen for the condition, but its widespread use for this application has been hindered by cost and the availability of appropriately trained technicians.

However, there's mounting evidence that medical personnel with no previous training can effectively use ultrasound to screen for AAA, especially with point-of-care ultrasound.

"The objective of our study was to determine whether a medical student, after a short training period, could reliably screen for abdominal aortic aneurysms," the group wrote. "We compared the test characteristics of point-of-care ultrasound performed by a medical student versus physical examination by vascular surgeons and a gold standard reference scan."

For the study, the researchers included data from 57 patients who presented to an outpatient vascular surgery clinic between October 2015 and March 2016 to be screened for abdominal aortic aneurysm. A vascular surgeon evaluated each patient via physical exam, followed by a second-year medical student using POCUS; patients then underwent a reference CT or vascular sonographer-performed ultrasound exam within three months of this initial screening visit.

The student had three hours of training with POCUS for detecting and measuring AAA. The training included a theoretical component led by a vascular sonographer and a practical component taught by an emergency physician, during which the student practiced ultrasound scanning under direct guidance.

After this initial training, the student practiced using ultrasound on the abdominal aortas of 60 patients with and without the condition. The student then completed a competency assessment before beginning to scan study participants, Mai and colleagues wrote.

Most of the patients (61%) were men, and the median patient age was 71. Reference exams identified 16 abdominal aortic aneurysms with a mean maximum aortic diameter of 29.5 mm. Of these, the vascular surgeon identified 11, with two false positives, for a sensitivity rate of 66.7% and a specificity rate of 94.4%. The average time to conduct the physical exam was 35 seconds.

Medical students using point-of-care ultrasound found 15 of the 16 abdominal aortic aneurysms with a mean maximum aortic diameter of 28 mm, for a sensitivity rate of 93.3% and a specificity rate of 100%. The average time to conduct the ultrasound exam was four minutes, the group wrote.

Physical exam vs. POCUS for AAA screening
Measure	Physical exam	Point-of-care ultrasound
Sensitivity	68.8%	93.8%
Specificity	93.9%	100%
Positive predictive value	81.8%	100%

All results were statistically significant.

"The results of our study, as well as several others, have proven that physical examination is relatively unreliable for the detection of abdominal aortic aneurysms," the researchers noted. "Screening for abdominal aortic aneurysms may be accurately and efficiently performed by a novice operator using point-of-care ultrasound with relatively limited training and experience."

Core curriculum?

Because point-of-care ultrasound appears to be an effective tool for identifying AAA, perhaps its use should be more formally incorporated into the medical school curriculum, Mai's team suggested.

"This study raises the question of whether we should be changing the way we are teaching medical students," the group wrote. "With the increased prevalence and use of ultrasound in medical practice, perhaps we should consider teaching focused ultrasound for abdominal aortic aneurysm detection as a standard in the medical school curriculum."

How to Perform GI Tract by Ultrasound

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