Discussion
The list of drugs that are used to treat oncohematological patients is long, since the long road to treatment, the prescription of multicomponent therapy leads to multiple complications, which in turn require correction and treatment, as well as the appointment of additional drugs. Paroxysms of ventricular tachycardia can clinically manifest as episodes of loss of consciousness and often end in ventricular fibrillation, which is the immediate cause of sudden death (5). Thus, when prescribing medications, it is necessary to bear in mind the possibility of increasing the risk of death in patients with an increased likelihood of developing ”Torsade de Pointes” and to monitor the duration of the QT interval (6). Prolongation of this interval is often associated with cardiotoxicity and is drug-induced (7).
One of the most important and significant tasks of cardiology is the early detection and treatment of patients with a high risk of sudden cardiac death (SCD). One of the most dangerous diseases with a risk of developing SCD of arrhythmogenic genesis is long QT syndrome (LQTS), in which the risk of SCD reaches 71% (6). According to a prospective study by the International LQTS Registry, 57% of SCD cases occur before the age of 20 (7). In 2016, under the auspices of the European Society of Cardiology Committee for the Development of Practice Guidelines, a document was released that talks about the treatment of cancer patients with chemoradiation therapy, as a result of which cardiovascular toxicity occurs (8). The document provides evidence of the severe effects of chemoradiation therapy on the myocardium: myocardial dysfunction and chronic heart failure (CHF), coronary artery disease, heart valve damage, arrhythmias (especially dangerous, induced by drugs that prolong the QT interval), arterial hypertension, thromboembolism, peripheral vascular disease and strokes, pulmonary hypertension, pericarditis. A fairly large group of chemotherapeutic drugs has a cardiotoxic effect, which can be expressed as asymptomatic ECG changes and myocardial infarction, as well as the development of toxic cardiomyopathy with symptoms of severe heart failure (7,8).
The importance of this clinical case lies in the fact that the direction of treatment and the use of drugs may not always have a positive effect on cardiac activity. Side effects and drug incompatibilities can lead to prolongation of the QT/QTc interval. As you know, prolongation of the QT/QTc interval often leads to fatal cardiac arrhythmias and is a predictor of sudden cardiac death. To date, there are a lot of studies that carefully describe the various causes of acquired lengthening of the interval (5,9,10). The QT interval corrected according to the Bazett formula, with a duration of more than 450 ms in men and more than 470 ms in women is considered to be elongated, normal – less than 430 and 450, borderline – from 430 to 450 and from 450 to 470 (7). A QT interval greater than 500 ms is a predictor of ventricular arrhythmias and sudden cardiac death; therefore, it is recommended to immediately discontinue the drugs causing these changes (6). In this clinical case, according to Holter’s results, a life-threatening heart rhythm disturbance was revealed, namely, an acquired QT/QTc interval lengthening. Cardiac arrhythmias are often detected in patients with cancer who receive chemotherapy (9). They range from rare cardiac arrhythmias to life-threatening arrhythmias or even sudden cardiac death (10). Arrhythmias can lead to trauma in the event of loss of consciousness, heart failure, or cardioembolic stroke in atrial fibrillation, requiring significant adjustments to the patient’s treatment regimen (5). Arrhythmia in patients with oncohematological pathology does not have any distinctive features but can be directly associated with a malignant neoplasm, induced by a chemotherapeutic drug, or occur against the background of an existing disease of the cardiovascular system (5,6). This work examines the features of the manifestation of the syndrome, taking into account the patient’s diagnosis and treatment tactics of the underlying disease and its complications. Long QTc syndrome is a common side effect of non-cardiac drugs (5,6). To prevent this kind of complications, physicians must consider the potential risks associated with the effect of LP on the QT interval. Patients who receive combinations of drugs that affect the duration of the QT interval should be warned about the need to promptly inform the attending physician about any symptoms that may be manifestations of ”Torsade de Pointes”. To detect asymptomatic prolongation of the QT interval of more than 500ms, it is necessary to regularly conduct an electrocardiographic examination. It is important to share cases of cardiac arrhythmias associated with a combination of different drugs to reduce mortality from arrhythmias in a cohort of hematological cancer patients. Given this clinical case, it should be noted that more careful monitoring of the QT/QTc interval during the patient’s treatment can have a beneficial effect on the successful outcome of the prescribed therapy (8).