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Obesity: number of risk factors determines risk of cardiovascular events

Cardiometabolic risk factors more dangerous than obesity on its own
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(Vienna, 03 March 2021) Obesity is closely linked with cardiometabolic risk factors such as hypertension, hyperlipidaemia and diabetes. However, there has long been controversy about the impact of obesity on cardiovascular events, such as strokes and heart attacks, in the absence of these risk factors. An international study group with participation from MedUni Vienna has now shown that it is not obesity per se that increases the probability of cardiovascular disease but the number of these additional risk factors that are present. The paper has recently been published in the leading international journal Diabetes Care (IF 16.019). March 4th is World Obesity Day.

Working with experts from Harvard Medical School and Duke University, Andreas Kammerlander from the Division of Cardiology within the Department of Medicine II of MedUni Vienna and Vienna General Hospital studied the influence of obesity as a function of cardiovascular risk factors in patients with stable angina pectoris, who had had a coronary computed tomography (CT) scan as part of the PROMISE study.

Obesity alone does not increase risk
Under the supervision of Udo Hoffmann (Massachusetts General Hospital, Harvard Medical School), it was shown that obesity does not increase the risk of a significant coronary stenosis or cardiovascular event in metabolically healthy patients. The presence of more than two risk factors or diabetes in non-obese patients was associated with the highest risk.

Half of all Austrians over the age of 15 overweight
Obesity is becoming increasingly prevalent throughout the world. In the USA, it is estimated that half of all adults will have a body mass index (BMI) ≥30kg/m2 by 2030. Even though the figures are slightly lower in Austria, it was found that in 2019 half the Austrian population over the age of 15 was overweight (BMI ≥25 kg/m2) or obese (BMI ≥30). Obesity is a known risk factor for the development of hypertension, hyperlipidaemia and diabetes, which in turn are risk factors for cardiovascular disease. People who, although considered obese based on a BMI >30 kg/m2, do not develop any of these risk factors, are often referred to as "metabolically healthy obese" (MHO). However, there is controversy about the association of this metabolic phenotype and hardly any data are available about patients with suspected coronary artery disease (CAD).

As part of his overseas placement at the Cardiovascular Imaging Research Center (Massachusetts General Hospital, Harvard Medical School), funded by the Austrian Society for Cardiology, Andreas Kammerlander was able to study the association between obesity and cardiovascular risk factors of different metabolic phenotypes. This study looked at patients with stable angina pectoris, who had been 1:1 randomised into two further investigation groups as part of the "Prospective Multicenter Imaging Study for Evaluation of Chest Pain" (PROMISE) study, either undergoing a functional test (stress electrocardiography, nuclear medicine procedure or echocardiography stress test) or anatomical imaging via a coronary CT scan. Based on 4,381 patients in the coronary CT group, the authors were able to show that different metabolic phenotypes, defined by the number of cardiovascular risk factors and the presence of obesity, have different characteristics in terms of their CAD profile and the risk of cardiovascular events.

Number of risk factors determines risk of cardiovascular events
The results indicate that it is primarily the number of risk factors, rather than the presence of obesity, that is associated with a high risk of severe CAD and cardiovascular events. Surprisingly, the highest risk of all was found in the patient group that was not obese but had a lot of cardiovascular risk factors. The results lead the researchers to the question of how obesity could be better defined, since BMI clearly has many limitations. In a follow-up project, the researchers are analysing fat and muscle characteristics that can be measured by CT, in order to gain a better understanding of the interaction between fatty tissue, cardiometabolic risk factors and cardiovascular events and to be better able to predict them.  

Service: Diabetes Care
Association of Metabolic Phenotypes With Coronary Artery Disease and Cardiovascular Events in Patients With Stable Chest Pain
Andreas A. Kammerlander, Thomas Mayrhofer, Maros Ferencik, Neha J. Pagidipati, Julia Karady, Geoffrey S. Ginsburg, Michael T. Lu, Daniel O. Bittner, Stefan B. Puchner, Nathan A. Bihlmeyer, Nandini M. Meyersohn, Hamed Emami, Svati H. Shah, Pamela S. Douglas, Udo Hoffmann on behalf of the PROMISE Investigators

Diabetes Care 2021 Feb; dc201760.