Brian Lacy, MD, PhD: Profiling Gastric Activity Variations with Multiday Testing

Brian Lacy, MD, PhD

Credit: Mayo Clinic

New research is shining light on discordance between “snapshot” gastric emptying tests and gastric sensorimotor disorder symptoms, highlighting the value of multiday ambulatory testing for detecting variations in gastric activity profiles under real-world conditions.

The study, which was led by Brian Lacy, MD, PhD, of the Mayo Clinic in Jacksonville, was presented at the American College of Gastroenterology (ACG) 2024 Annual Scientific Meeting in Philadelphia, Pennsylvania, and suggests the value of a wireless motility patch for detecting daily variations in gastric myoelectrical activity typically missed by current tests and guiding more personalized approaches to patient care.

The study included 37 adults who were referred for a 4-hour, solid phase, scintigraphic gastric emptying scan (GES) and wore 3 wireless motility patches for 6 days while recording mealtimes and bowel movements using an iPhone app. During a mean 4.9 days of recording, 5 individuals demonstrated delayed gastric emptying of < 75% at 4 hours in the GES test, conducted on day 1. Of these patients, 3 had weak gastric myoelectrical activity, 1 had moderate, and the other had strong gastric activity in the multiday test. Of note, a daily GutPrint for the high-activity patient revealed both weak and strong days with a weak peak on the day of the GES test.

Investigators averaged meal responses over the multiday test and found weaker meal response (P = .048) within the delayed gastric emptying group, additionally pointed out the weak activity group had greater variation in day-to-day activity than the other groups (P = .054, .092).

The editorial team of HCPLive Gastroenterology spoke with Lacy for additional insight into study findings and the shortcomings of current gastric emptying tests in the following Q&A:

HCPLive: Why is it important that gastric myoelectrical activity measurements are specific to symptoms and patient-reported outcomes?

Lacy: This is a great question in the setting of a lot of controversy in the field. Symptoms of common gastric sensory and motor disorders, including functional dyspepsia and gastroparesis, are, unfortunately, neither sensitive nor specific.

Patients with gastric sensory and motor disorders may report symptoms of early satiety, epigastric fullness, epigastric pressure pain, bloating, nausea and even vomiting. However, these symptoms cannot accurately distinguish functional dyspepsia from gastroparesis and may not predict response to therapy. These symptoms frequently lead to testing which may include a gastric emptying scan. However, the small-volume, low-fat meal performed over 4 hours may not be an accurate representation of underlying gastric motor activity. The test provides just a brief “snapshot” of gastric activity and likely does not accurately report the physiology of the gastrointestinal tract in the ambulatory setting where patients eat larger meals and meals that are higher in fat content. By measuring gastric myoelectrical activity over a prolonged period in the outpatient setting we were able to identify unique patterns of activity categorized as weak, moderate, or strong.

These findings may change therapy. For example, a patient with weak gastric myoelectrical activity and symptoms of epigastric fullness and nausea may respond well to a prokinetic agent. However, a patient with similar symptoms of epigastric fullness and nausea but very strong gastric myoelectrical activity may feel worse with a prokinetic agent and may do better with an agent that improves gastric accommodation. This is a fascinating area of research and we hope to report more novel results in the next year.

HCPLive: What relationship between “snapshot” tests like gastric scintigraphy and patient symptoms were observed in this study, and what is the significance of these findings?

Lacy: In our prior pilot study, we measured symptoms during the gastric emptying scan. However we could not identify any specific relationship for symptoms during the low-fat, small-volume meal, and the underlying diagnosis of functional dyspepsia, gastroparesis, or chronic nausea and vomiting. We thus modified our protocol and during the current study, which included 37 patients, we did not routinely measure symptoms during the gastric emptying scan.

However, we did identify several very interesting findings which are worth highlighting. One, patients with functional dyspepsia had a reduced meal response in the stomach. The reduced gastric activity could explain symptoms of fullness early satiety and postprandial nausea. This is a novel finding that has not previously been reported. Two, patients with chronic nausea and vomiting, who did not have gastroparesis, had higher intestinal activity than patients with nausea. It is possible that a stronger Mayo electric response in the intestine underlies symptoms of vomiting in these patients and thus medications to help reduce that strong activity might prove more useful than standard antiemetic therapy. Finally, and maybe not surprisingly, there was variation in day-to-day recordings. This is important because this likely represents the true physiology of the patient. We need to be careful about making major treatment decisions based on a 4-hour gastric emptying scan using a low-fat low-volume meal that may not be typical of meals at home or meals while eating out.

HCPLive: How might the use of this wireless motility patch to capture gastric activity profiles under real-world conditions help providers individualize patient care?

Lacy: Using data from this novel study could help individualize patient care in a number of settings. Let’s consider one patient with symptoms of early satiety, nausea, and occasional vomiting. The patient comes in for a gastric emptying scan but the small volume, low-fat meal shows normal gastric emptying that day. That finding, which may not accurately reflect the true physiology of the upper GI tract, could lead to treatment with an anti-emetic agent, which may not be entirely unreasonable. However, a 6-day ambulatory wireless patch test might show that when eating meals at home that are larger in size and higher in fat content, gastric myoelectrical activity is low. This might then lead to the use of a prokinetic agent which might greatly improve the patient's symptoms.

Editors’ note: Lacy has relevant disclosures with AbbVie, Ardelyx, Ironwood Pharmaceuticals, Takeda, and others.

Reference

^{Lacy BE, Cangemi DJ, Accurso J, et al. P1620 - Beyond the Snapshot: Multi-Day Motility Measurement Captures Day-to-Day Variation in Gastric Activity. Paper presented at: ACG 2024 Annual Scientific Meeting. Philadelphia, Pennsylvania. October 25-30, 2024.}