Researchers Link NAFLD to Infarct Size in Patients with STEMI 

A clinically relevant association exists between non-alcoholic fatty liver disease (NAFLD) and infarct size in patients with ST-elevation Myocardial Infarction (STEMI), according to research presented Thursday by Feier Ding, a researcher at The University of Osaka. 

“NAFLD is a very common condition linked to overweight and obesity where excess fat builds up in the liver,” Ding said. “It’s now the most prevalent chronic liver disease, affecting about 30% of people globally.”  

She also noted that the phenomenon known as the “obesity paradox,” whereby obese patients sometimes have better prognoses after experiencing a cardiovascular event, occurs in certain cardiovascular diseases. 

Thus, the researchers sought to determine whether NAFLD has a protective effect against acute vascular events. 

To do so, they designed a study that included 117 individuals who had experienced a primary STEMI. Twenty-three people in the cohort also had NAFLD, and 94 of them did not. The median age was 63 years in the NAFLD group and 65.5 years in the non-NAFLD group. The vast majority in both groups were men: 91.3% with NAFLD vs. 79.8% without. 

There were no significant differences between the groups in other important factors, including body mass index (BMI), blood pressure, fasting blood glucose, diabetes prevalence, total cholesterol and LDL, the specific blocked artery causing the heart attack, or rates of hypertension, smoking or family history of heart disease.

The investigators used single photon emission CT myocardial perfusion imaging (SPECT-MPI) to identify myocardial infarct size (MIS). They also used CT scans to measure intrathoracic fat, pericardial fat and NAFLD.

They divided the patients into two groups: those whose heart attacks had a measurable size and those whose did not. They used a two-sample t-test to see if there were differences in the types of body fat between these two groups. This helped them determine which kind of fat might be connected to the size of the heart attack. The investigators then used linear regression analysis to evaluate the association between the related fats and MIS. 

Gene Links Help Heart Attack Prediction

The next step for the researchers was to look for genes that might be linked to both types of body fat and associated with related fat and acute myocardial infarction. To do this, they used a large public database of genetic information called the Gene Expression Omnibus (GEO) database. The team employed Pearson’s correlation analysis to confirm the association between the expression of shared genes in the serum of STEMI patients and related fat.

The most significant metabolic difference between patients in the two groups was that patients with NAFLD had significantly higher triglyceride levels, according to the study’s lead author Weiwei Cui, PhD, of Tianjin Fourth Central Hospital, The Affiliated Hospital of Tianjin Medical University in China. In addition, NAFLD patients were significantly less likely to have an infarction in the posterior wall of the left ventricle.

The investigators hope the study results lead to radiologists considering key points when interpreting images for heart attack patients, including that a finding of fatty liver on a scan done for cardiac reasons may have important implications beyond the liver itself. 

The data indicate that the link with infarct size appears to be more specific to fat in the liver, as the researchers did not observe a significant association with fat deposits directly surrounding the heart (pericardial or intrathoracic fat), according to Dr. Cui. 

The liver-to-spleen attenuation ratio on CT emerged in the study as an independent predictor of infarct size. In Dr. Cui’s view, this suggests that routinely reporting this ratio could potentially provide valuable prognostic information and help in risk stratification for these patients.

Using Research Findings to Flag High-Risk Patients 

These findings have the potential to improve patient outcomes by enabling better risk stratification, Dr. Cui noted. 

By assessing the liver on a CT scan that a heart attack patient may already be receiving, he asserted, radiologists and clinicians can identify those with NAFLD who are at risk for more severe heart damage. 

These high-risk patients could then be targeted for more aggressive medical therapy, closer monitoring and stricter management of their cardiovascular and metabolic health factors after the heart attack to improve their long-term prognosis, he stated.

“This study is among the first to directly link a CT-based measure of NAFLD to the actual size of a heart attack, measured by SPECT-MPI,” Dr. Cui noted. “More importantly, it explored the underlying biology and identified the sST2 protein as a potential molecular link. The fact that sST2 levels in the blood correlated with both the imaging and molecular findings provides a compelling, multi-layered story that strengthens the association.”

Access the session, “Association Between Non-Alcoholic Fatty Liver Disease and Myocardial Infarct Size in Patients with ST-Elevation Myocardial Infarction: A Cross-Sectional Study and Bioinformatics Analysis Based on the GEO Database,” (R1-SSNMMI07-5) on demand at RSNA.org/MeetingCentral.