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Grapefruit juice may prolong QT interval
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SAN FRANCISCO — Patients who drank 2 L grapefruit juice within several hours had significant corrected QT interval prolongation, especially in women and those with long QT syndrome, according to data presented at Heart Rhythm Society Annual Scientific Sessions.
The results of this study were also published in HeartRhythm.
“If grapefruit juice was a new ‘drug,’ then the Food and Drug Administration would likely request the addition of a ‘warning’ to its ‘patient information leaflet,’” Ehud Chorin, MD, PhD, of the department of cardiology at Tel Aviv Sourasky Medical Center in Israel, told Cardiology Today. “We have known proarrhythmic drugs for more than 44 years. Our manuscript suggests that we should be thinking about ‘proarrhythmic food’ as a realistic possibility.”
In this randomized crossover study, researchers analyzed data from 30 participants with QT syndrome. Participants were assigned 2 L grapefruit juice in three divided doses or 400 mg oral moxifloxacin.
“All the medications that prolong the QT interval do it mainly by blocking a specific potassium channel on the myocardial cell membrane: the channel for the rapid component of the delayed-rectifier potassium current, or ‘IKr,’ thus prolonging the ventricular repolarization,” Chorin said in an interview. “It has been reported in the past that some flavonoids contained in pink grapefruit juice block the IKr channel in vitro.”
Ten additional participants with congenital long QT syndrome were also given grapefruit juice in the study.
Participants assigned grapefruit juice had significant corrected QT prolongation for a net of 14 milliseconds (95% CI, 6.2-21.7).
Grapefruit juice and moxifloxacin had similar effects on QT prolongation in healthy participants. This effect from grapefruit juice was greater in women and those with long QT syndrome with a net of 21.8 milliseconds (95% CI, 3.4-35.3).
“Our study does not imply that daily consumption of grapefruit juice involves any measurable risk for the general population,” Chorin told Cardiology Today. “A possible exception could be the consumption of health drinks containing highly concentrated grapefruit products. The effects of such products on the QT interval need to be investigated.” – by Darlene Dobkowski
References:
Chorin E, et al. Abstract S-PO03-191. Presented at: Heart Rhythm Society Annual Scientific Sessions; May 8-11, 2019; San Francisco.
Chorin E, et al. HeartRhythm. 2019;doi:10.1016/j.hrthm.2019.04.039.
Disclosure: Chorin reports no relevant financial disclosures.