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).