Association of In-Hospital Antimalarial–Macrolide Therapy With 3–6-Month Cardiac Electrophysiological Outcomes in Survivors of Severe COVID-19: A Matched Retrospective Cohort Study
In a matched retrospective cohort study of severe COVID-19 survivors, short-term in-hospital exposure to combined antimalarial–macrolide therapy was not associated with persistent QTc prolongation or clinically significant cardiac electrophysiological abnormalities at 3–6 months, though observed differences in heart rate and variability may be confounded by acute disease severity.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
In the early days of the global pandemic, doctors faced a terrifying uncertainty: a new virus was spreading rapidly, causing severe lung damage, and there were no proven treatments to stop it. In this climate of urgency, medical teams turned to medications that had been used for decades to treat malaria and bacterial infections. Two types of drugs were often given together: antimalarials, which were thought to calm the body's overactive immune response, and macrolides, a class of antibiotics. However, these drugs carry a known risk. They can interfere with the electrical signals that tell the heart to beat, potentially stretching out the time it takes for the heart muscle to recharge between beats. If this recharge time gets too long, it can trigger dangerous, irregular heart rhythms. While doctors monitored patients closely while they were in the hospital, a lingering question remained for the survivors: once the infection cleared and the drugs were stopped, did these electrical changes stick around? Did the heart remain vulnerable months later, or did it return to normal?
To answer this, a team of researchers in Mexico City followed a group of people who had survived severe cases of the virus. They focused on those who had received the combination of antimalarial and macrolide drugs during their hospital stay. The team matched these patients with others who had suffered from the same severity of illness but had not received those specific medications. The goal was to see if the treatment left a lasting mark on the heart's electrical system. Several months after leaving the hospital, when the patients were feeling better, the researchers performed detailed heart tests. They looked at the electrical timing of the heartbeat, checked for irregular rhythms, and measured how well the heart's natural pacemaker adjusted to daily life.
The results offered a picture for the survivors who had received the treatment that requires careful interpretation. When the researchers measured the time it took for the heart to recharge, known as the corrected QT interval, they found no difference between the two groups. The average measurement was about 420 milliseconds for those who took the drugs and 423 milliseconds for those who did not. This tiny difference was not statistically significant, meaning it was likely just random variation rather than a real effect of the medication. Furthermore, the study found no cases of dangerous, life-threatening heart rhythms in either group. The drugs, which had raised alarms during the acute phase of the pandemic, did not appear to cause any persistent electrical problems once the patients had recovered, though the study noted it was too small to definitively rule out extremely rare events.
There were some differences in how the hearts of the two groups behaved, but they pointed in a direction opposite to what one might fear. The patients who had taken the antimalarial and antibiotic combination actually had slightly slower resting heart rates and showed better heart rate variability, a sign that the nervous system was regulating the heart effectively. In contrast, the group that did not receive these drugs had more severe inflammation during their hospital stay, spent more time in the intensive care unit, and had longer hospitalizations. Their hearts showed signs of more strain, with higher rates of irregular rhythms and less variability in their beating patterns.
The researchers suggest that these findings are likely due to the severity of the illness itself rather than the drugs. The group that did not receive the specific treatment had a heavier burden of inflammation and a more difficult recovery, which may have temporarily disrupted their heart's electrical stability. The group that received the treatment had a smoother hospital course, and their hearts seemed to recover more fully. However, the researchers emphasize that differences in heart rate and variability should be interpreted with caution, as the unexposed group's more severe acute illness could have influenced the results. While the study was small and could not rule out extremely rare events, it suggests that the short-term use of these medications during the pandemic did not leave behind a hidden, long-term danger to the heart's electrical system in this cohort. For the survivors of severe COVID-19, the heart's electrical rhythm appears to have returned to a stable state, regardless of whether they had received those specific medications months earlier.
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