Try the new high dose dual therapy with PPI q6h and  Amoxicillin 750 mg q6h, it works in Taiwan (90% eradication)

First of all, stop the treatment and verify the persistence of the infection after a 30-45 day period with a non invasive test. then, if still infected, a quadruple bismuth-based should be the choice.

Not use clarithromycin and medication with metabolic to CYP3A4/

Clarithromycin is contraindicated in patients with hypersensitivity to the macrolide antibiotics and should be used with caution in patients with liver disease or certain heart problem such as QT prolongation, or who are taking HIV drugs. For these patients, dual therapy may be a useful therapeutic option for H. pylori infection, 

dual therapy with 750 mg amoxicillin and 30 mg lansoprazole three times daily for 2 weeks was similar in effectiveness to the standard triple therapy and had fewer side effects when given as first-line treatment for H. pylori.

Macrolide antibiotics affect cellular recepters e.g. enhance motilin receptor in the GIT and similarly on cardiac myocytes and this effect might be also similar to the effect of prokinitic drug  Cisapride

prolonged Qt was not identified, some patients presented diarrhea that was self-limited, tolerable. If there is no tolerance or allergy to penicillin or treatment failure,quadruple therapy with bismuth, tetracycline, furazolidone, and omeprazole was given for 10 days.

Thanks all for the replies and opinions!

Now I see that my question is not understood and answered in this way.

It was about an adverse event during a course of eradication with clarithromycin.

And what if the situation arises?

- Eradication by this line is interrupted.

- An adverse reaction notice is filled out to the regulatory organization.

- ECG check

- A new eradication regimen without macrolides is prescribed after ecg normalization.

- A note is made in the medical record about the interrupted eradication scheme with clarithromycin (due to a side effect).

Best regards