Hydroxychloroquine Linked To Increased Risk Of Irregular Heartbeat

BOSTON — The malaria drug hydroxychloroquine has emerged as a potential treatment for COVID-19, but a new study from the Harvard-affiliated Beth Israel Deaconess Medical Center is throwing some cold water on that idea. A team of doctors and pharmacists have found evidence that receiving hydroxychloroquine as a COVID-19 treatment can significantly raise one’s risk of developing electrical changes in their heart and cardiac arrhythmias (irregular heartbeat).

Patients who received a combination of hydroxychloroquine with azithromycin (an antibiotic) were found to be at an even higher risk of heart complications.

“While hydroxychloroquine and azithromycin are generally well-tolerated medications, increased usage in the context of COVID-19 will likely increase the frequency of adverse drug events (ADEs),” says co-first author Nicholas J. Mercuro, a pharmacy specialist in infectious diseases at BIDMC, in a release. “This is especially concerning given that that patients with underlying cardiac co-morbidities appear to be disproportionately affected by COVID-19 and that the virus itself may damage the heart.”

Both of these drugs have been known to cause electrical disturbances in the heart known as a QTc prolongation. Basically, this disturbance causes the heart to take milliseconds longer than normal to “recharge” between heart beats. A few milliseconds may seem inconsequential, but this development can promote an irregular heart beat, which in turn raises one’s risk of heart attack, stroke, and death.

For this research, 90 adult COVID-19 patients were analyzed. All of those patients were treated at BIDMC between March 1st and April 7th, and each had received at least one day of hydroxychloroquine treatment. Over half of the examined patients had pre-existing high blood pressure, and more than 30% were diabetic. Meanwhile, 53 of those patients also received azithromycin.


In all, seven (19%) of those patients developed prolonged QTc of 500 milliseconds or more, and another three saw their QTc increase by 60 milliseconds or more. Among the studied patients who were given azithromycin in addition to hydroxychloroquine, 21% developed prolonged QTc of 500 milliseconds or more and 13% saw a change of at least 60 milliseconds.

“In our study, patients who were hospitalized and receiving hydroxychloroquine for COVID-19 frequently experienced QTc prolongation and adverse drug events,” comments co-first author Dr.Christina F. Yen, of BIDMC’s Department of Medicine. “One participant taking the drug combination experienced a potentially lethal tachycardia called torsades de pointes, which to our knowledge has yet to be reported elsewhere in the peer-reviewed COVID-19 literature.”

On top of all these concerning cardiac findings, the jury is still very much out regarding hydroxychloroquine’s effectiveness against COVID-19. While the drug has shown some promise against coronaviruses, dating back to SARS in 2003, no study thus far has been able to confirm it can adequately stop a COVID-19 infection. So, in conclusion, this study’s authors say hydroxychloroquine should only be used as a COVID-19 treatment option after “caution and careful consideration.”

“If considering the use of hydroxychloroquine, particularly combined with azithromycin, clinicians should carefully weigh the risks and benefits, and closely monitor QTc — particularly considering patients’ co-morbidities and concomitant medication use,” concludes senior author Dr. Howard S. Gold, an infectious disease specialist at BIDMC and an assistant professor of medicine at Harvard Medical School. “Based on our current knowledge, hydroxychloroquine for the treatment of COVID-19 should probably be limited to clinical trials.”

The study is published in JAMA Cardiology.

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John Anderer

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