Links of interest have been added where you will find information about the interactions of these medicines, as well as automated formulas for QT correction. In addition, the algorithm recently proposed by the Mayo Clinic for decision-making during the use of hydroxychloroquine and azithromycin has been adapted in patients with COVID-19, with respect to QTc (Table 2).
#INTERVALO QT NORMAL ECG HOW TO#
LAHRS in collaboration with the Colombian College of Electrophysiology and the Argentine, Brazilian, and Mexican Societies of Cardiac Electrophysiology (SADEC, SOBRAC, SOMEEC) wish to contribute to the mitigation of the risk of occurrence of this type of arrhythmias by the elaboration of this practical document on how to measure the QT interval, their normal values and ranges in which there is true risk associated with QT prolongation in order to help identify not only patients with long QT at baseline but also those at risk of further abnormal prolongation in response to the initiation of therapy for COVID-19 (Table 1). For these reasons, an increase in the occurrence of malignant arrhythmias such as “torsade de pointes” or ventricular fibrillation with indiscriminate use of these drugs is expected if preventive measures are not established (Fig. This risk may be further increased by the wide interaction of these drugs with countless medications such as antibiotics, antiarrhythmics, anesthetics, and muscle relaxants, among others ( ).
However, it is very important to note that all of these medicines can pathologically prolong the QT interval in patients at high risk by genetic predisposition (with congenital long QT syndrome or in patients with polymorphisms but without phenotypic expression) or those with acquired predisposition. Although the clinical evidence supporting their use is scarce and mostly limited to in vitro studies, the off label use of these drugs as first-line therapy and even as prophylaxis has spread very quickly in face of the progression of the epidemic and the high mortality rate in susceptible populations. One of these therapeutic strategies suggests the use of immune response modulating drugs such as chloroquine and hydroxychloroquine (antimalarials) alone or in combination with azithromycin (macrolide antibiotic) the use of antivirals such as ritonavir and lopinavir have also been suggested. COVID-19 infection has shown rapid growth worldwide, and different therapies have been proposed for treatment, especially in critical patients with acute respiratory failure.