Scientists Created Model to Determine Risks of Sudden Cardiac Arrest

According to Maksim Kashtanov, Sverdlovsk doctors perform 20-30 operations a year for this genetic disease.
Photo Credit: from Maksim Kashtanov's personal archive

European and Russian scientists have developed a model for predicting the risks of sudden cardiac arrest after alcohol septal ablation (ASA) for hypertrophic obstructive cardiomyopathy (HOCM). In other words, after surgery to remove a hypertrophic fragment of the left ventricular septum, which prevents normal blood flow to the aorta. The created model is a new word in science: before that the regularities of sudden cardiac arrest after ASA have not been investigated, the modern system of risk assessment for postoperative patients was absent. Meanwhile, HOCM is the cause of 30% of cases of sudden cardiac arrest.

The researchers' recommendations will contribute to the timely identification of patients at risk of sudden cardiac arrest after alcohol septal ablation and to the most effective treatment of hypertrophic obstructive cardiomyopathy. An article about the research was published in the American Journal of Cardiology.

The researchers analyzed the medical histories of more than 1,830 patients seen in clinics in Germany, the Czech Republic, Denmark, the Netherlands, Great Britain, and Russia. The analysis covered the period from 1996 to 2021. The study is the most extensive and in-depth to date. In developing the model, the authors used Russian statistics that have been forming since 2001. Data from Russia - Ekaterinburg and St. Petersburg - accounted for one-third of the statistical base of the study.

"In the Sverdlovsk region, hypertrophic obstructive cardiomyopathy is a relatively common disease. Suffice it to say that, according to the literature data, pathological genes occur in one of 200 patients, and hypertrophy larger than 15 millimeters - in one of 500 patients. Every year we examine about 100 patients with such a diagnosis and perform 20-30 operations," explains Maksim Kashtanov, Head of the Laboratory of Biomedical Engineering at Ural Federal University, surgeon of the Department of X-Ray Diagnostic and Treatment Methods at Sverdlovsk Regional Hospital No. 1, co-author of the research and article.

International studies have shown that 65 patients (3.5 percent of the total) experienced sudden cardiac arrest. Thirty-seven of them, almost half of them, died.

"Genetic predisposition, age, and left atrial and left ventricular dysfunction are known to be key factors that increase the risk of sudden cardiac arrest and death. The risk of sudden cardiac arrest is indicated by chest pain, weakness, and shortness of breath. A multivariate analysis demonstrated that predisposing factors of sudden cardiac arrest after alcohol septal ablation are preoperative excessive interventricular septal thickness and difference in blood pressure between the left ventricle and the aorta at the last clinical examination," says Maksim Kashtanov.

According to the researchers' scale of threatening symptoms, the most dangerous combination is when the septal thickness is 20 or more millimeters and the difference in blood pressure levels in the left ventricle and the aorta is 30 or more millimeters of the mercury column. For patients with such parameters the risk of sudden cardiac arrest after alcohol septal ablation is 2 percent per year. Such patients need maximum reduction of blood pressure in the left ventricle by repeated ablation, and if the risks persist, implantation of a cardiac defibrillator or expensive drug treatment.

"The created technique is characterized by prognostic accuracy and can be applied as a simple and easily accessible clinical tool for predicting the risk of sudden cardiac arrest in patients with hypertrophic obstructive cardiomyopathy after alcohol septal ablation," Maksim Kashtanov emphasizes.

Reference

Hypertrophic obstructive cardiomyopathy is considered a genetic disorder in which there is excess wall thickness of the heart. In two-thirds of cases, this results in left ventricular obstruction, which means that there is a pressure difference between the left ventricle and the aorta. This results in a constant pressure overload of the heart, which can be compared to such a clinical situation as a hypertensive crisis. As a result, the risks of both thrombosis and ischemic stroke as well as sudden cardiac arrest increase significantly. Cystic fibrosis can occur at different ages, including at birth, but most commonly between 50 and 60 years of age. In the young, it takes the most severe forms. The older the age at which HOCM occurs, the more productive the treatment.

Left ventricular outflow tract obstruction is effectively treated by alcohol septal ablation, which does not require a thoracic incision. Using punctures of the radial or femoral artery, a small amount of alcohol is injected into the vessels of the heart. This results in localized myocardial necrosis, shrinking of the basal septum and resulting left ventricular dilation and relief of symptoms. After ASA, up to 80 percent of patients recover, while 20 percent require open heart surgery - surgical myectomy.

Source/Credit: Ural Federal University

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