Ultrasound links meat allergen to heart disease

By Kate Madden Yee, AuntMinnie.com staff writer

June 15, 2018 -- Using intravascular ultrasound (IVUS), researchers from the U.S. National Institutes of Health (NIH) have found a link between sensitivity to an allergen in red meat and plaque buildup in the heart's arteries, according to a study published online June 14 in Arteriosclerosis, Thrombosis, and Vascular Biology.

Only recently have scientists identified the main allergen in red meat, called galactose-alpha-1,3-galactose, or alpha-Gal, wrote a team led by Dr. Coleen McNamara from the University of Virginia Health System. It's also been discovered that the lone star tick, found predominately in the southeastern U.S., sensitizes people to this allergen when it bites them, boosting the incidence of meat allergies in this area.

Researchers have suspected for some time that allergens can trigger immunological changes that may be associated with plaque buildup and artery blockages. In their study, McNamara and colleagues showed that a type of antibody (immunoglobulin) specific to the alpha-Gal allergen was associated with higher levels of arterial plaque.

The investigators analyzed blood samples from 118 adults and found antibodies to alpha-Gal in 26%. Next, they used intravascular ultrasound (IVUS) to analyze the quantity of plaque in the blood samples. The amount was 30% higher in the alpha-Gal-sensitized patients than in the nonsensitized patients.

Cross-sectional IVUS images of coronary arteries. Plaque buildup (colored areas) in an artery from a patient who lacks sensitivity to the red meat allergen (left) is much lower than plaque levels in an artery from a patient with sensitivity to the allergen (right). Images courtesy of Dr. Angela Taylor of the University of Virginia Health System.

"This novel finding from a small group of subjects from Virginia raises the intriguing possibility that allergy to red meat may be an underrecognized factor in heart disease," McNamara said in a statement released by the NIH. "These preliminary findings underscore the need for further clinical studies in larger populations from diverse geographic regions and additional laboratory work."

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.