After the heart attack, the fat in the heart scar ignites the most dangerous arrhythmias
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It is a dangerous cocktail for the heart. On the one hand there are the unfortunately indelible scars of the lifeless myocardial tissue subjected to prolonged ischemia with cell death. On the other hand, there are the striae of fat that merge with the scar lesions themselves, creating a sort of biological basis that would favor the onset of potentially very serious arrhythmias, such as ventricular fibrillation. On average, these phenomena occur a few years after the heart attack and are difficult to predict. Now, by tracing the deposits of adipose tissue along the lines of the scar tissue, it is possible to identify in advance the subjects at greater risk of arrhythmia and then implement targeted countermeasures.
Study the digital models of the heart
To offer these perspectives is a research published in Nature Cardiovascular Researchwhich has seen protagonists among other scholars such as Natalia Travanova Johns Hopkins University, Eric Sung and Jonathan Chrispin of the same university e Saman Nazarian of the University Hospital of Pennsylvania. The difficulty of the investigation lies in the possibilities of evaluating fat with normal imaging techniques.
If it is true that heart scars appear on a contrast MRI scan, a CT scan with contrast is required to assess the presence of adipose tissue inside them. And it is difficult to find people who have a heart attack who undergo both controls during the monitoring period. For this 24 patients were evaluated: from the images obtained real digital models of the heart were made and, also evaluating the electrophysiological tests to treat arrhythmias, it was possible to understand how much and how the fat in the scars is important in determining the paintings.
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The risk of ventricular fibrillation
The researchers found that having higher amounts of fat in the heart wall of patients increased the risk of developing arrhythmias. The same was not the case considering the amount of scar tissue in the myocardium. In practice, when fat is present, the conduction of electrical signals that regulate the heart rhythm is slowed down. The result is that there is an increased risk of rhythm disorders and in particular of ventricular fibrillation, the most frequently fatal arrhythmia that causes cardiac arrest.
When the arrhythmia appears, the left ventricle contracts even hundreds of times per minute in a completely independent way with respect to the atrium above, which instead maintains its normal rhythm. This situation quickly leads to a very serious haemodynamic problem, that is linked to the flow of blood. In fact, the “crazy” contractions of the ventricle are completely ineffective, with a great electrical activity which however results in the substantial absence of the contraction. So each time the blood introduced into the aorta is far less than the needs of the organism. Within seconds, then there is a state of severe ischemia to the heart itself, the brain and other organs which, if the underlying arrhythmia is not treated, can lead to death.
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Hopes for future treatment
“The study, albeit on a limited number of patients, focuses on a very refined definition of the post-infarct cardiac scar: this is composed of fibrosis and can also coexist with adipose tissue – he explains. Giulio Molon, director of Cardiology at the Irccs Sacro Cuore-Don Calabria in Negrar. In particular, the research carefully identifies fat, with MRI and CT, and correlates it to a greater presence of ventricular tachycardias, also with the use of electroanatomical mapping of the studied part. Furthermore, patients treated with radio-frequency ablation of the area involved, to eliminate the tachycardias that originate from there, show areas of more extensive ablation, ie the fat tissue also makes the ablation procedure more difficult “.
The investigations therefore provide very useful information, also in perspective, especially for the possibility of identifying patients at greater risk of developing threatening ventricular arrhythmias and therefore with increased mortality. “Furthermore, the analysis of the adipose tissue could allow to be guided more precisely in the ablations, in the areas with the greatest presence of fat and to use more effective ablation therapies, to eliminate the adipose tissue in depth with greater energies, with catheters or energies. or techniques different from the usual ones, “adds Molon. All this, not to mention of course specific medical therapies, aimed at reducing the formation of fat in the scar or eliminating / reducing it once it has been created, to preserve heart health.
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