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DETAILS OF THE EUROPEAN STUDY ( PUBLISHED IN THE JOURNAL, EP Europace ):

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With safety and efficacy questions still lingering, a team of European scientists looked at 649 coronavirus patients between 10 March and 10 April.

The patients were first assessed for their QT prolongation risk, a sign of arrhythmias.

Hydroxychloroquine can cause a dangerous electrical change in the heart of some patients. This is called QT prolongation due to the pattern it makes on an electrocardiogram.

Although the drug has been used for decades for other conditions, the coronavirus pandemic is the first time it has been taken by large numbers of acutely ill patients with multiple health conditions, who may also be on other drugs that cause QT prolongation as a side effect.

The scale of the coronavirus outbreak raises the risk any one patient may have a pre-existing heart condition that predisposes them to arrhythmias.

Changes in blood electrolytes – electrically-charged minerals in the body that can trigger arrhythmias – can also occur in those needing intensive care.

Once the participants’ QT prolongation risk was found to be low, they were given 200mg of hydroxychloroquine twice a day.

More than half (58.6%) took a “loading dose” – an initial large dose of a medicine to ensure a quick therapeutic response – on the first day.

Hydroxychloroquine was administered soon after symptom onset in three settings: 126 (19.4%) patients were managed at home, 495 (76.3%) were in a hospital ward and 28 (4.3%) were in intensive care.

To mirror real-world conditions, around a third (30%) of the patients were on two drugs that can cause QT prolongation – one being hydroxychloroquine, and 13.6% were taking three of the medications.

The results – published in the journal EP Europace – revealed a statistically significant increase in QT prolongation across all three settings, however, this was modest and similar regardless of where the patient was treated.

Around 16 days after taking hydroxychloroquine, none of the arrhythmias that occurred were lethal.

Seven (1.1%) of the participants had a serious ventricular arrhythmia, which the scientists did not link to hydroxychloroquine.

“Hydroxychloroquine treatment was associated with QT prolongation, as expected, but the change was small,” said study author Dr Alessio Gasperetti from the Monzino Cardiology Centre in Milan.

“There was no connection between the drug and the occurrence of arrhythmias.

“The study shows hydroxychloroquine administration, alone or in combination with other potentially QT-prolonging drugs, is safe for short-term treatment of COVID-19 patients at home or in hospital, provided they undergo risk assessment and ECG [electrocardiogram] monitoring by a physician.”