To Fast or Not to Fast Before Elective Cardiac Catheterization

Doug Brunk

May 21, 2020

No restriction of oral food intake prior to nonemergent cardiac catheterization is as safe as the current traditional NPO [nothing by mouth] strategy, results from a large, single-center, randomized controlled trial showed.

According to lead investigator Abhishek Mishra, MD, NPO after midnight has been a standard practice before major surgery requiring general anesthesia since Mendelson Syndrome was first described in 1946.

"The rationale for keeping NPO after midnight has been to keep the stomach empty, to reduce gastric contents and acidity — which would reduce emesis — and eventually reduce the risk of aspiration," Dr. Mishra, a cardiologist at the Heart and Vascular Institute at Vidant Health in Greenville, N.C., said at the at the Society for Cardiovascular Angiography & Interventions virtual annual scientific sessions.

"The rationale of NPO in the setting of cardiac catheterization is to reduce the risk of aspiration, and more so, of a patient needing emergent cardiac surgery," Dr. Mishra added. "The clinical question was, do we really need to keep our patients NPO prior to elective cardiac catheterization? So far, no large randomized study has been done to answer this question."

To find out, Dr. Mishra and colleagues carried out CHOW NOW (Can We Safely Have Our Patients Eat With Cardiac Catheterization — Nix or Allow), a single-center, prospective, randomized, single-blinded study that compared the safety of a nonfasting strategy with the current fasting protocol strategies in 599 patients who underwent nonemergent cardiac catheterization at The Guthrie Clinic/Robert Packer Hospital in Sayre, Pa.

Patients in the fasting group were instructed to be NPO after midnight, but could have clear liquids up to 2 hours prior to the procedure, while those in the nonfasting group had no restriction of oral intake, irrespective of time of cardiac catheterization. The primary outcome was a composite of aspiration pneumonia, preprocedural hypertension, preprocedural hypoglycemia or hyperglycemia, incidence of nausea/vomiting, and contrast-induced neuropathy. Secondary outcomes included total cost of the index hospitalization, patient satisfaction via a questionnaire containing seven questions, and in-hospital mortality.

Of the 599 patients, 306 were assigned to the standard fasting group and the remaining 293 to the nonfasting group. Their mean age was 67 years, 45% were on a proton pump inhibitor or H2 blockers, and 33% had diabetes. In addition, 40% had acute coronary syndrome, and 23% underwent percutaneous intervention.

The researchers observed no statistically significant difference in the primary or secondary outcomes between the study groups. In the nonfasting group, 11.3% of patients met the primary endpoint, compared with 9.8% of the patients in the standard fasting group (P = .65). In addition, the nonfasting strategy was found to be noninferior to the standard fasting strategy for the primary outcome at a noninferiority margin threshold of 0.059.

Dr. Mishra and colleagues observed no differences between the standard fasting and nonfasting groups with respect to in-hospital mortality (0.3% vs. 0.7%, respectively; P = .616), patient satisfaction score (a mean of 4.4 vs. a mean of 4.5; P = .257), and mean total cost of hospitalization ($8,446 vs. $6,960; P = .654).

"In this randomized, controlled trial, we found that there was no significant difference in the rate of overall adverse events with an approach of unrestricted oral intake prior to cardiac catheterization compared to strict fasting, and it was associated with better patient satisfaction and lower cost of care, especially for hospitalized patients," concluded Dr. Mishra, who conducted the research during his fellowship at The Guthrie Clinic.

He acknowledged certain limitations of the trial, including the fact that results are applicable only to cardiac catheterization procedures, including coronary angiographies, percutaneous coronary interventions, and left heart catheterizations. "These results are not applicable to certain high-risk coronary procedures that required the use of a large-bore access or any valve procedures," he said.

One of the session's invited panelists, SCAI President Cindy L. Grines, MD, said that she and other interventional cardiologists have "gone around and around" on the issue of NPO prior to nonemergent cardiac catheterization. "I actually let my patients get fluids up until the time they're put on the cath lab table," said Dr. Grines, chief scientific officer of the Northside Cardiovascular Institute in Atlanta. "I haven't been giving them solid food like this, though."

Another panelist, Timothy D. Henry, MD, said that in his clinical experience, "patients don't like being NPO, and I think we've all seen cases where patients are actually volume-depleted in the morning." Dr. Henry, medical director of The Carl and Edyth Lindner Center for Research and Education at The Christ Hospital in Cincinnati, pointed out that most NPO policy "is not dictated by us as interventional cardiologists; it's dictated by hospital policies or by anesthesiologists. Will [the results of this study] change what we do?"

The Donald Guthrie Research Foundation funded the study. Daniel P. Sporn, MD, FACC, was the study's principal investigator. Dr. Mishra reported having no financial disclosures.

Society for Cardiovascular Angiography & Interventions (SCAI) 2020 Scientific Sessions: Abstract 11758.

Doug Brunk can be reached at dbrunk@mdedge.com. This article originally appeared on MDedge.

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