There is not a single heart attack, there are various types. The best known case, the classic one, is represented by acute and complete occlusion of a coronary artery. But there are also situations where the occlusion is partial or intermittent. In all cases it is essential to intervene as soon as possible, both to remove the occlusion of the artery and restore the blood circulation, and to prevent tissue damage. Among the consequences of heart attack, in fact, there is the death of cells and the formation of scars, even very extensive, which alter the function of the heart and which can lead to heart failure (or decompensation). Now a study conducted on animal models by the National University of Ireland in Galway could open up a new avenue of research to try to reduce harm. The new possibility consists in the use of a particular hydrogel, a substance which, when injected into the heart wall, has been shown to be able to preserve the tissue and improve its functionality after a heart attack. These first results are published in Science Traslational Medicine.
Prevent scarring
Fibrotic structures are needed to repair injuries and are more extensive the longer you wait before treating the heart attack. The heart failure they can lead to is an insidious and very serious disease, even fatal. But once the damage is done how can it be repaired? “To date we do not have effective tools to deal with the problem,” he stresses Giuseppe Tarantini, President of the Italian Society of Interventional Cardiology (Gise): “The line of research based on the use of stem cells, in fact, has met with failure in clinical studies on human beings”.
I study
This is why various research groups around the world are hypothesizing and testing new treatment options. The Irish researchers, coordinated by the Italian Paolo Contessotto, studied what happens in a sample of sheep with a type of heart attack called NSTEMI (without ST-segment elevation), which does not involve the full thickness of the heart wall and which is generally less severe than “traditional” heart attack ( classified as STEMI, with elevation of the ST segment). If in the acute phase it may be easier to treat, however, NSTEMI can be dangerous in the long term even for survival. “It is a type of heart attack more frequent in elderly patients”, Tarantini underlines, “who have incomplete occlusions that can involve several vessels”.
The idea of Contessotto’s group is to use not stem cells but a particular hydrogel. The hydrogel is built to mimic the extracellular matrix of the heart, which is not composed of cells and which in fact represents the network, the structure, in which the various components of the tissue are pigeonholed. Injected into the myocardium, the hydrogel forms a degradable scaffold that appears to help restore tissue structure in sheep. In some (still very few) animals with NSTEMI infarction, 21 days after injection, the hydrogel restored the normal volume of fluid expelled from the heart chamber with each contraction. It also reduced scarring and promoted the regrowth of blood vessels in damaged regions.
Preliminary results
The result suggests the importance of deepening the investigation into other animal models and in the future studying ways to perform these procedures on humans, a path currently not viable. “The work is interesting and valuable”, comments Tarantini, not involved in the work, “given that it is part of a new line of research and opens up new study frontiers. However, it should be noted that currently it is not possible to make generalizations and in any way extend the data to human patients “. The reasons are various: “The results – underlines the president of the Gise – were obtained on an animal model whose cardiac apparatus has various differences compared to ours. Furthermore, the onset in the laboratory of a heart attack in animals is a completely different event compared to what happens in humans “. And it is not certain that what has been observed, once transferred to us, remains valid. “A critical example – adds Tarantini – is represented precisely by the failure of the use of stem cells I mentioned, which instead had shown positive effects in animals”.
In short, the leap is still too large. In the meantime, prevention is essential. “To date – concludes Tarantini – the main action to limit damage remains timely intervention. In the presence of symptoms and pain, the patient must immediately call 118, which often during the pandemic, for fear of contagion, did not happen, with many more risks and complications for the person with a heart attack “.
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