Study Finds No Link To Arrhythmias From Oral Fluoroquinolones Antibiotics Interview with:
Malin Inghammar, MD, PhD
Department of Infectious Diseases
Skåne University Hospital, Lund
Sweden What is the background for this study?

Dr. Inghammar: Fluoroquinolones are a class of antibiotics with a widespread use in the treatment of common infections. Agents of this drug are generally well tolerated and have few side effects but in some people fluoroquinolones can prolong the QT-interval. QT-prolongation is a sort of electrical disturbance in the heart that can, in rare instances, lead to potentially life-threatening arrhythmia. Some drugs are well known to cause QT-prolongation and to be able to trigger arrhythmia. Fluoroquinolones however, have only weak effect on the QT-time. There have been a few previous studies published reporting an increased risk. Some of these, compared fluoroquinolone treated patients with people who were not treated with antibiotics at all. In these studies, it can’t be ruled out that the infection itself, rather than the antibiotic treatment could have influenced the risk of arrhythmia. In some other previous studies, there have been indications that the patients receiving fluoroquinolones were of poorer general health than the comparison group, which could also have affected the results. Therefore it is not clear if oral fluoroquinolone treatment leads to an increased risk of serious cardiac arrhythmia in an everyday clinical situation. What are the main findings?

Dr. Inghammar: We used unique Danish and Swedish national registries to evaluate the risk of arrhythmia. Over 900.000 treatment courses with oral fluoroquinolones in outpatients were identified. These were compared with 900.000 control courses of penicillin V, an antibiotic with no known effect on the heart. We found no evidence supporting an increased risk of serious arrhythmia for the fluoroquinolone treated patients in the Danish and Swedish data. We specifically studied certain subgroups who are known to be extra vulnerable, such as patients with an underlying heart disease or patients who are already on treatment with other drugs that are known to increase the risk of arrhythmia. Reassuringly, the results were homogenous and we did not find evidence supporting an increased risk in these groups either. What should clinicians and patients take away from your report?

Dr. Inghammar: We did not find support for an increased risk of serious arrhythmia associated with oral fluoroquinolone use in a general adult outpatient population in Sweden and Denmark.

The most commonly prescribed fluoroquinolone in Sweden and Denmark was ciprofloxacin. We did not find any support for differences between the different fluoroquinolone agents, but we cannot exclude that less frequently used fluoroquinolones may influence the risk of arrhythmia differently. What recommendations do you have for future research as a result of this study?

Dr. Inghammar: Our results apply only to outpatients treated with oral fluoroquinolones, the risk of arrhythmia need to be further assessed in more seriously ill patients that require hospital stay. Also, the less prescribed fluoroquinolones, such as Moxifloxacin, need to be studied in better powered studies to evaluate if these carry a different risk as compared to the more frequently prescribed fluoroquinolones. Thank you for your contribution to the community.


Inghammar Malin, Svanström Henrik, MelbyeMads, Pasternak Björn, Hviid Anders. Oral fluoroquinolone use and serious arrhythmia: bi-national cohort study BMJ 2016; 352 :i843

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Malin Inghammar, MD, PhD (2016). Study Finds No Link To Arrhythmias From Oral Fluoroquinolones Antibiotics 

Last Updated on March 11, 2016 by Marie Benz MD FAAD