What was the cause of my client’s irregular heartbeat he experienced today? Will this need further work with the Lightworker Healing Protocol?

This indeed was the reacquisition of spirit meddlers following their removal from your Protocol session you did yesterday on his behalf. The newcomers picked up where the others left off and looked at their former handiwork and went right to work perturbing the heart. So an additional session will be needed for him. He is someone who will need some repeat monitoring and removals to consolidate the gains and build inner resistance to keep him safe going forward. Indeed, this has been the cause of his prior cardiac issues, that the nerves are being perturbed by spirit attachments, so this bodes well for maintaining his good health provided he can be protected and kept free of spirit attachments in the future.