JAR Med manual states:
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Right bundle branch block [(RBBB)]
Incomplete right bundle branch block is seen in 2–3% of routine flight crew
electrocardiograms and appears to carry a normal prognosis in asymptomatic subjects. No special requirements are needed.
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The above diagnoses were printed in the ECG printout? Those ECG machines sometimes make false diagnoses. The final diagnosis is made by the AME himself.
So no worries there. If someday the RBBB becomes complete, they might do some additional test. I would be suprised if they did any further testing at this point for class 2 medical.