Variations in glucose levels may indicate severity of heart attack damage

According to research conducted by Brazilian scientists, high glucose levels may serve as a biomarker indicating a worse outcome in patients who have experienced their first acute myocardial infarction.

The study demonstrated that glycemic variability, particularly glycemic delta, is associated with the size of the infarction and a reduction in left ventricular ejection fraction (LVEF). LVEF shows the strength of the heart’s contraction; if it is reduced, heart failure may result.

Based on a sample of 244 individuals treated at Hospital São Paulo, the study concluded that higher glycemic delta is associated with worse myocardial damage, regardless of whether the patient has diabetes. Glycemic delta is obtained by calculating the admission blood glucose level (measured upon arrival at the hospital) minus the estimated average blood glucose level for the previous months, based on glycated hemoglobin obtained through a blood test.

To evaluate muscle loss and heart damage, a magnetic resonance imaging scan was performed 30 days after the heart attack. The study group included scientists from three Brazilian research institutions – the Federal University of São Paulo (UNIFESP), the Dante Pazzanese Institute, and the Albert Einstein Jewish Brazilian Hospital – as well as from Laval University in Canada. The results of the study were published in the journal Diabetology & Metabolic Syndrome.

“The findings surprised us, and based on our literature review, they were unprecedented. They open a number of doors for us to further study the pathophysiology of patients who have had a myocardial infarction,” cardiologist Henrique Tria Bianco, a professor at UNIFESP and corresponding author of the article, told Agência FAPESP.

The study received support from FAPESP through a Thematic Project under the guidance of UNIFESP professor Francisco Antonio Fonseca, and involved researcher Maria Cristina Izar. Both are also co-authors of the article.

“Through a simple, inexpensive test that almost all patients do, which is glycated hemoglobin for hospital admission, we end up with an easy-to-obtain biomarker with important implications. In other words, patients with a higher delta will have greater infarct mass and will need myocardial protection, both in relation to blood glucose and, for example, the use of beta-blockers, to improve their prognosis,” says Fonseca.

Acute myocardial infarction is the leading cause of death in Brazil. According to the Ministry of Health, there are an estimated 300,000 to 400,000 cases annually, resulting in one death for every five to seven cases. Also known as a heart attack, it is characterized by the death of heart muscle cells due to clots that suddenly and severely interrupt blood flow. Symptoms include chest pain or discomfort that may radiate to the back, face, and arm, particularly the left arm. The pain is usually intense and prolonged and is accompanied by a feeling of heaviness or tightness in the chest. Other symptoms include sweating, paleness, shortness of breath, and faintness. To reduce the risk of death, treatment must be administered within the first few minutes.

‘Gold standard’

The sample included patients over 18 years of age who received fibrinolytics (medication that dissolves the thrombus causing the heart attack) within six hours of the onset of symptoms. The patients were initially treated at SUS (Brazil’s national public health network) units that specialize in this type of treatment. Then, they were transferred to Hospital São Paulo, which is part of UNIFESP. Some of the patients had diabetes, some had prediabetes, and some did not have diabetes.

The “gold standard” treatment for myocardial infarction initially includes primary angioplasty and fibrinolysis induction.

Among the patients undergoing pharmacoinvasive treatment, the greatest glycemic delta was associated with a larger infarct and lower LVEF. “We now have a way to validate these results in other populations and verify how much it impacts patient health,” explains Bianco.

According to the researchers, future investigations should clarify the molecular pathways and cellular mechanisms involved in this process. Additionally, they should seek targeted therapeutic interventions to mitigate adverse outcomes in high-risk populations.

The study, which began ten years ago, also analyzed data related to patient mortality. The results will be published in the future.

About São Paulo Research Foundation (FAPESP)
The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.