Malnutrition Linked to Mortality, MACE in ACS Patients

Among patients with acute coronary syndromes, malnutrition seems common and is tied to increases in mortality and cardiovascular events, according to a new Spanish analysis.

“To identify malnourished patients is a chance for clinical cardiologists to improve the prognosis of patients with acute coronary syndrome,” lead author Sergio Raposeiras Roubín, MD, PhD (Hospital Álvaro Cunqueiro, Pontevedra, Spain), told TCTMD in an email. “This is very important in cardiac rehabilitation units; those units should include nutritional intervention programs.”

The study confirms previous evidence showing that low body mass index (BMI) worsens a patient’s prognosis following a cardiovascular event, and in fact, the obesity paradox has been previously described to show an advantage for patients with a BMI between 25-30, explained Darryl Leong, MBBS, MPH, PhD (McMaster University, Hamilton, Canada), who was not involved in the study. However, he told TCTMD, “the quantification of diet is a difficult thing to do and it's also difficult in clinical practice where the physician’s time may be limited . . . . Having a nutritionist or dietician as part of the healthcare team to first measure patient's dietary intake and to provide guidance as to what might constitute a better diet would be important.”

This added expertise could also help alert physicians to the presence of unrecognized chronic disease that may be leading to loss of appetite, cachexia, and malnutrition, Leong added.

The study was published in the August 18, 2020, issue of the Journal of the American College of Cardiology.

Increase in Mortality, MACE

For the study, Roubín and colleagues retrospectively observed 5,062 ACS patients (40.4% STEMI) admitted to their institution between January 2010 and September 2017. Nutrition status was classified by the following metrics:

• BMI: underweight (< 18.5 kg/m²), normal weight (18.5-24.9 kg/m²), overweight (25.0-29.9 kg/m²), and obese (≥ 30 kg/m²)
• Controlling Nutritional Status score (CONUT): 0-12 range, with 0 being normal and 12 being severe malnutrition
• Nutritional Risk Index (NRI): severe (< 83.5), moderate (83.5-97.5), mild (97.5-100), and no nutritional risk (≥ 100)
• Prognostic Nutritional Index score (PNI): normal > 38, moderate malnutrition 35-38, severe malnutrition < 35

Malnourishment, either moderate or severe, was identified among 11.2%, 39.5%, and 8.9% of patients according to the CONUT, NRI, and PNI scores, respectively. Almost three-quarters (71.8%) were deemed to be at least mildly malnourished by at least a single score, and 59.9% were defined as moderately or severely malnourished by all three scores. Interestingly, a wide range of patients with BMIs below 25 kg/m² (8.4-36.7%) were deemed to be malnourished depending on which nutritional score was used.

Over a median follow-up period of 3.6 years, 16.4% of patients died (primary endpoint) and 20.7% experienced MACE. Both moderate and severe malnutrition heightened the risk of mortality compared with good nutritional status across all three measurement indices.

Adjusted Mortality Risk by Malnourishment Score and Level

MACE risk also was increased for those defined as moderately or severely malnourished by both the CONUT and PNI risk scores but only for those defined as severely malnourished by the NRI index. Additionally, each of the malnourishment scores improve the ability of the GRACE risk score to predict both all-cause mortality and MACE, with the CONUT index giving the highest incremental value.

Roubín told TCTMD that while he was surprised to see such a high prevalence of malnourishment in the patient cohort, the results are likely representative across the globe. “In our study, we included all patients with acute coronary syndrome—we [did not] exclude any type of patients,” he said. “We think that although the rate maybe is slightly different in another regions, the malnutrition rate will be relevant in another hospitals.”

Interpreting Malnutrition

Leong, however, said it was a “huge surprise” to see that more than half of the enrolled patients had evidence of malnutrition. “The word ‘malnutrition’ may be what is causing some interpretive issues here, because the measurements that go into these malnutrition indices are actually not specific to nutrition,” he explained. “For example, you can have a low albumin or an altered lymphocyte count for a number of reasons that are not specifically wedded to nutrition. Or even more to the point, you could have poor nutrition as a consequence of other chronic disease and it's really those other chronic diseases that are contributing to the excess mortality seen in this population rather than specifically any dietary deficiencies.”

Because of this, the definition of malnutrition used in this study is not specific enough, according to Leong. “So, I would like to see other confirmatory evidence that a poor dietary intake—and again that is open for debate as to what that actually constitutes—is associated with poor outcomes in patients with acute coronary syndrome,” he said.

In an accompanying editorial, Andrew M. Freeman, MD (National Jewish Health, Denver, CO), and Monica Aggarwal, MD (University of Florida, Gainesville), write that “malnutrition is a largely underrecognized and undertreated condition by clinicians, especially in patients with normal or increased BMI. People often see increased abdominal girth as overnutrition rather than undernutrition. However, poor nutrient quality is an important source of malnutrition and is associated with increased mortality in patients with ACS.”

Because of this, the editorialists say that treatment of at-risk patients should include “a nutritional status assessment and counseling on how to shift toward a diet that is rich in these healthier food options. In fact, many of these index hospitalizations for life-threatening events can prove valuable as teaching moments to truly affect care and change treatment trajectories.”

They also encourage the participation of nutritionists and dieticians as part of the care team because cardiologists don’t often have the knowledge or training in proper nutritional care. “Paying lip service with the usual phrases, such as ‘Be sure to exercise and eat right,’ simply doesn’t cut it,” Freeman and Aggarwal write. “It behooves us as a profession to ensure adequate training and competency in the delivery of care in the lifestyle space.”

Going forward, Leong said he would like to see future studies look more at the global effects of malnutrition on cardiovascular health. “The study reported up to a 50-60% prevalence of malnutrition in the Spanish population. If this is true, consider how frequently you would define someone as malnourished in a low-income country. It must be a large majority of individuals,” he said. “So, I think that more research ought to be focused on the contribution of low-resource, low-income settings to poor or undernutrition and its role in either cardiovascular disease or worsening outcomes in individuals with cardiovascular disease.”

Additionally, the use of more-quantifiable tools like food diaries and food frequency questionnaires could potentially give more specific information about the relationship between diet and clinical outcomes, Leong said. “I think that that would provide a more-refined definition of malnutrition as opposed to the sort of measurements that were used in this study.”