In a statement, the trust said it had begun the process of writing to each person, offering them the opportunity to meet a consultant cardiologist to go through the results of the review process.
It added it was only focusing on patients who had a CRT device inserted by Lau.
A number of patients have already been seen by a specialist consultant cardiologist involved in the review process at a dedicated clinic and more will be seen in the coming weeks.
They will be notified by letter.
A relation of one of those patients said the letter had caused a lot of distress.
Sources told BBC News NI some consultants were angry about the length of time it takes the trust to review a consultant’s work.
One medic said that the review process is unnecessarily lengthy and causes distress among patients and frustration between doctors in the affected department.
The Trust has an advice line on 028 9615 0100 which is open from 09:00 – 20:00 on Friday 15 May and 10:00 -14:00 on Saturday and Sunday 17 May.